Tabl
eofCont
ent
s
1
I
nt
r
oduct
i
on
P.1
2
Basi
cPr
i
nci
pl
esofSound
P.8
3
ThePr
opagat
i
onofSound
P.12
4
ModesofPr
opagat
i
on
P.18
5
Ul
t
r
asoundGener
at
i
on
P.22
6
Fact
or
sAf
f
ect
i
ngt
hePr
opagat
i
onofUl
t
r
asound
P.25
7
TheDeci
bel
(
DB)
P.27
8
Snel
l
’
sLaw
P.29
9
Equi
pment
P.32
10
Cal
i
br
at
i
onBl
ocks
P.44
11
0°Pr
obeScanni
ng
P.50
12
Ul
t
r
asoni
cEqui
pmentChecks
P.60
13
Sensi
t
i
v
i
t
ySet
t
i
ng
P.70
14
Fl
awLocat
i
on
P.78
15
Pr
esent
at
i
on
P.91
16
I
dent
i
f
y
i
ngFl
awsi
nBut
tWel
ds
P.94
17
Pr
act
i
cal
Wel
dI
nspect
i
on
P.98
18
Wel
dDef
ect
s
P.
101
19
Ul
t
r
asoni
cTest
i
ngofCast
i
ngs
P.
107
20
Ul
t
r
asoni
cTest
i
ngofFor
gi
ngs
P.
113
1I
nt
r
oduct
i
on
Nondest
r
uct
i
v
et
est
i
ngi
st
heabi
l
i
t
yt
oexami
neamat
er
i
al
(
usual
l
yf
or
di
scont
i
nui
t
i
es)wi
t
houtdegr
adi
ngi
t
.
Thef
i
v
epr
i
nci
pal
met
hods,
ot
hert
hanv
i
sual
i
nspect
i
on,
ar
e:
 Penet
r
antt
est
i
ng
 Magnet
i
cpar
t
i
cl
ei
nspect
i
on
 Eddycur
r
entt
est
i
ng
 Radi
ogr
aphy
 Ul
t
r
asoni
ct
est
i
ng
I
nal
lt
heNDTmet
hods,i
nt
er
pr
et
at
i
onofr
esul
t
si
scr
i
t
i
cal
.Muchdependsont
he
ski
l
land exper
i
ence of t
he t
echni
ci
an,al
t
hough pr
oper
l
yf
or
mul
at
ed t
est
t
echni
quesandpr
ocedur
eswi
l
l
i
mpr
ov
eaccur
acyandconsi
st
ency
.
1.
1 Penet
r
antt
est
i
ng
Penet
r
antt
est
i
ngl
ocat
essur
f
acebr
eaki
ngdi
scont
i
nui
t
i
esbycov
er
i
ngt
hei
t
em
wi
t
hapenet
r
at
i
ngl
i
qui
d,whi
chi
sdr
awni
nt
ot
hedi
scont
i
nui
t
ybycapi
l
l
ar
yact
i
on.
Af
t
err
emov
aloft
heexcesspenet
r
antt
hei
ndi
cat
i
oni
smadev
i
si
bl
ebyappl
i
cat
i
on
ofadev
el
oper
.Col
ourcont
r
astorf
l
uor
escentsy
st
emsmaybeused.
Adv
ant
ages:
 Appl
i
cabl
et
ononf
er
r
omagnet
i
cs
 Abl
et
ot
estl
ar
gepar
t
swi
t
ha
 por
t
abl
eki
t
 Bat
cht
est
i
ngAppl
i
cabl
et
osmal
l
par
t
swi
t
h
 compl
exgeomet
r
y
 Si
mpl
e,
cheapeasyt
oi
nt
er
pr
et
 Sensi
t
i
v
i
t
y
Di
sadv
ant
ages:
 Wi
l
l
onl
ydet
ectdef
ect
sopent
ot
heSur
f
ace
 Car
ef
ul
sur
f
acepr
epar
at
i
onr
equi
r
ed
 Notappl
i
cabl
et
opor
ousmat
er
i
al
s
 Temper
at
ur
edependant
 Cannotr
et
esti
ndef
i
ni
t
el
y
 Compat
i
bi
l
i
t
yofchemi
cal
s
1.
2 Magnet
i
cpar
t
i
cl
ei
nspect
i
on
Magnet
i
cpar
t
i
cl
ei
nspect
i
oni
susedt
ol
ocat
esur
f
aceandsl
i
ght
l
ysubsur
f
ace
di
scont
i
nui
t
i
esi
nf
er
r
omagnet
i
cmat
er
i
al
sbyi
nt
r
oduci
ngamagnet
i
cf
l
uxi
nt
ot
he
mat
er
i
al
.Adv
ant
ages:
 Wi
l
l
det
ectsomesubsur
f
acedef
ect
s
 Rapi
dandsi
mpl
et
ounder
st
and
 Pr
ecl
eani
ngnotascr
i
t
i
cal
aswi
t
hDPI
 Wi
l
l
wor
kt
hr
ought
hi
ncoat
i
ngs
 Cheapr
uggedequi
pment
 Di
r
ectt
estmet
hod
Di
sadv
ant
ages:
 Fer
r
omagnet
i
cmat
er
i
al
sonl
y
 Requi
r
ementt
ot
esti
n2di
r
ect
i
ons
 Demagnet
i
sat
i
onmayber
equi
r
ed
 Oddshapedpar
t
sdi
f
f
i
cul
tt
ot
est
 Notsui
t
edt
obat
cht
est
i
ng
 Candamaget
hecomponentundert
est
1.
3 Eddycur
r
enti
nspect
i
on
Eddycur
r
enti
nspect
i
oni
sbasedoni
nduci
ngel
ect
r
i
calcur
r
ent
si
nt
hemat
er
i
al
bei
ngi
nspect
edandobser
v
i
ngt
hei
nt
er
act
i
onbet
weent
hosecur
r
ent
sandt
he
mat
er
i
al
.Eddycur
r
ent
sar
egener
at
edbycoi
l
si
nt
het
estpr
obeandmoni
t
or
ed
si
mul
t
aneousl
y by measur
i
ng t
he coi
l
s el
ect
r
i
cali
mpedance.As i
ti
s an
el
ect
r
omagnet
i
ci
nduct
i
onpr
ocess,di
r
ectel
ect
r
i
calcont
actwi
t
ht
hesampl
ei
snot
r
equi
r
ed;
howev
er
,
t
hemat
er
i
al
mustbeanel
ect
r
i
cal
conduct
or
.
Adv
ant
ages:
 Sensi
t
i
v
et
osur
f
acedef
ect
s
 Candet
ectt
hr
oughsev
er
al
l
ay
er
s
 Candet
ectt
hr
oughsur
f
acecoat
i
ngs
 Accur
at
econduct
i
v
i
t
ymeasur
ement
s
 Canbeaut
omat
ed
 Li
t
t
l
epr
ecl
eani
ngr
equi
r
edandPor
t
abl
e
Di
sadv
ant
ages:
 Ver
ysuscept
i
bl
et
oper
meabi
l
i
t
ychanges
 Onl
yonconduct
i
v
emat
er
i
al
s




Wi
l
l
notdet
ectdef
ect
spar
al
l
el
t
osur
f
ace
Notsui
t
abl
ef
orl
ar
gear
easand/
orcompl
exgeomet
r
i
es
Si
gnal
i
nt
er
pr
et
at
i
onr
equi
r
ed
Noper
manentr
ecor
d(
unl
essaut
omat
ed)
1.
4 Radi
ogr
aphy
Radi
ogr
aphymoni
t
or
st
hev
ar
y
i
ngt
r
ansmi
ssi
onofi
oni
si
ngr
adi
at
i
ont
hr
ougha
mat
er
i
alwi
t
ht
heai
dofphot
ogr
aphi
cf
i
l
m orf
l
uor
escentscr
eenst
odet
ectchanges
i
ndensi
t
yandt
hi
ckness.I
twi
l
l
l
ocat
ei
nt
er
nal
andsur
f
acebr
eaki
ngdef
ect
s.
Adv
ant
ages:
 Gi
v
esaper
manentr
ecor
d,
t
her
adi
ogr
aph
 Det
ect
si
nt
er
nal
f
l
aws
 Det
ect
sv
ol
umet
r
i
cf
l
awsr
eadi
l
y
 Canbeusedonmostmat
er
i
al
s
 Cancheckf
orcor
r
ectassembl
y
 Gi
v
esadi
r
ecti
mageoff
l
aws
 Fl
uor
oscopycangi
v
er
eal
t
i
mei
magi
ng
Di
sadv
ant
ages:
 Ther
ei
sar
adi
at
i
onheal
t
hhazar
d
 Canbesensi
t
i
v
et
odef
ector
i
ent
at
i
onandsocanmi
sspl
anarf
l
aws
 Hasl
i
mi
t
edabi
l
i
t
yt
odet
ectf
i
necr
acks
 Accessi
sr
equi
r
edt
obot
hsi
desoft
heobj
ect
 Ski
l
l
edr
adi
ogr
aphi
ci
nt
er
pr
et
at
i
oni
sr
equi
r
ed
 I
sar
el
at
i
v
el
ysl
owmet
hodofi
nspect
i
on
 Hasahi
ghcapi
t
al
costandr
unni
ngcost
1.
5 Ul
t
r
asoni
ct
est
i
ng
Ul
t
r
asoni
ct
est
i
ngmeasur
est
het
i
mef
orhi
ghf
r
equency(
0.
5MHz50MHz)pul
ses
oful
t
r
asoundt
ot
r
av
elt
hr
ought
hei
nspect
i
onmat
er
i
al
.I
fadi
scont
i
nui
t
yi
spr
esent
,
t
heul
t
r
asoundr
ef
l
ect
sbackt
ot
hepr
obei
nat
i
meot
hert
hant
hatappr
opr
i
at
et
o
goodmat
er
i
al
.Adv
ant
ages:
 Sensi
t
i
v
et
ocr
acksatv
ar
i
ousor
i
ent
at
i
ons
 Por
t
abi
l
i
t
y
 Saf
et
y
 Abl
et
openet
r
at
et
hi
cksect
i
ons
 Measur
esdept
handt
hr
oughwal
l
ext
ent
Di
sadv
ant
ages:
 Noper
manentr
ecor
d(
unl
essaut
omat
ed)
 Noteasi
l
yappl
i
edt
ocompl
exgeomet
r
i
esandr
oughsur
f
aces.
 Unsui
t
edt
ocoar
segr
ai
nedmat
er
i
al
s
 Rel
i
antupondef
ector
i
ent
at
i
on
1.
6 Choi
ceofmet
hod
Bef
or
edeci
di
ngonapar
t
i
cul
arNDTi
nspect
i
onmet
hodi
ti
sadv
ant
ageoust
ohav
e
cer
t
ai
ni
nf
or
mat
i
on:
 Reasonf
ori
nspect
i
on.(
Todet
ectcr
acks,
sor
tbet
weenmat
er
i
al
s,
check
assembl
y
,
et
c)
.
 Li
kel
yor
i
ent
at
i
onofpl
anardi
scont
i
nui
t
i
es,
i
ft
heyar
et
heanswert
ot
he
abov
equest
i
on.
 Ty
peofmat
er
i
al
.
 Li
kel
yposi
t
i
onofdi
scont
i
nui
t
i
es.
 Geomet
r
yandt
hi
cknessofobj
ectt
obet
est
ed.
 Accessi
bi
l
i
t
y
.
Thi
si
nf
or
mat
i
oncanbeder
i
v
edf
r
om:
 Pr
oductknowl
edge.
 Pr
ev
i
ousf
ai
l
ur
es.
Accur
acyofcr
i
t
i
cal
si
zi
ngofi
ndi
cat
i
onsv
ar
i
esf
r
om met
hodt
omet
hod.
Li
qui
dpenet
r
anti
nspect
i
on
Thel
engt
hofasur
f
acebr
eaki
ngdi
scont
i
nui
t
ycanbedet
er
mi
nedr
eadi
l
y
,
butt
he
dept
hdi
mensi
onscanonl
ybeassessedsubj
ect
i
v
el
ybyobser
v
i
ngt
heamountof
bl
eedout
.
Magnet
i
cpar
t
i
cl
ei
nspect
i
on
Thel
engt
hofadi
scont
i
nui
t
ycanbedet
er
mi
nedf
r
om t
hei
ndi
cat
i
on,
butno
assessmentofdi
scont
i
nui
t
ydept
hcanbemade.
Eddycur
r
enti
nspect
i
on
Thel
engt
hofadi
scont
i
nui
t
ycanbedet
er
mi
ned.Thedept
hofadi
scont
i
nui
t
yor
mat
er
i
al t
hi
nni
ng can be det
er
mi
ned by ampl
i
t
ude measur
ement
, phase
measur
ementorbot
h,but t
he t
echni
ques f
orcr
i
t
i
calsi
zi
ng ar
e somewhat
subj
ect
i
v
e.
Ul
t
r
asoni
ct
est
i
ng
The l
engt
h and posi
t
i
on of a di
scont
i
nui
t
y can be det
er
mi
ned. Dept
h
measur
ement
s ar
e mor
e di
f
f
i
cul
tbutcr
ack t
i
p di
f
f
r
act
i
on ort
i
meof
f
l
i
ght
t
echni
quescangi
v
egoodr
esul
t
s.
Radi
ogr
aphy
The l
engt
h and pl
an v
i
ew posi
t
i
on can be det
er
mi
ned.Thr
ought
hi
ckness
posi
t
i
oni
ngr
equi
r
esaddi
t
i
onalangul
at
edexposur
est
obet
aken.Thet
hr
ought
hi
cknessdi
mensi
onofdi
scont
i
nui
t
i
escannotr
eadi
l
ybedet
er
mi
ned.
1.
7 Hi
st
or
yoful
t
r
asoni
ct
est
i
ng(
UT)
I
nMedi
ev
alt
i
mescr
af
t
smencast
i
ngbel
l
sf
orchur
cheswer
eawar
et
hatapr
oper
l
y
castbel
lr
angt
r
uewhenst
r
uckandt
hatabel
lwi
t
hf
l
awswoul
dgi
v
eoutaf
al
se
not
e.Thi
spr
i
nci
pl
ewasusedbywheel
t
apper
si
nspect
i
ngr
ol
l
i
ngst
ockont
he
r
ai
l
way
s.Theyst
r
uckwheel
swi
t
hahammerandl
i
st
enedt
ot
henot
egi
v
enout
.A
l
ooset
y
r
esoundedwr
ong.
Theor
i
gi
nofmoder
nul
t
r
asoni
ct
est
i
ng(
UT)i
st
hedi
scov
er
ybyt
heCur
i
ebr
ot
her
s
i
n1880t
hatquar
t
zcr
y
st
al
scuti
nacer
t
ai
nwaypr
oduceanel
ect
r
i
cpot
ent
i
alwhen
subj
ect
edt
opr
essur
e-t
hepi
ezoel
ect
r
i
cef
f
ect
,f
r
om t
heGr
eekpi
edzei
n,t
opr
ess
orst
r
i
ke.I
n1881,
Li
ppmant
heor
i
sedt
hatt
heef
f
ectmi
ghtwor
ki
nr
ev
er
se,
andt
hat
quar
t
zcr
y
st
al
smi
ghtchangeshapei
fanel
ect
r
i
ccur
r
entwasappl
i
edt
ot
hem.He
f
oundt
hi
swasso andexper
i
ment
edf
ur
t
her
.Cr
y
st
al
sofquar
t
zv
i
br
at
ewhen
al
t
er
nat
i
ngcur
r
ent
sar
eappl
i
edt
ot
hem.Cr
y
st
almi
cr
ophonesi
namoder
nst
er
eo
r
el
yont
hi
spr
i
nci
pl
e.
Whent
heTi
t
ani
csanki
n1912,t
heAdmi
r
al
t
yt
r
i
edt
of
i
ndawayofl
ocat
i
ng
i
ceber
gs by sendi
ng out sound wav
es and l
i
st
eni
ng f
or an echo.They
exper
i
ment
edf
ur
t
herwi
t
hsoundt
odet
ectsubmar
i
nesdur
i
ngt
heFi
r
stWor
l
dWar
.
Bet
weent
hewar
s,
mar
i
neechosoundi
ngwasdev
el
opedandi
nt
heSecondWor
l
d
WarASDI
C(
Ant
i
Submar
i
ne Det
ect
i
onI
nv
est
i
gat
i
onCommi
t
t
ee)wasext
ensi
v
el
y
usedi
nt
heBat
t
l
eoft
heAt
l
ant
i
cagai
nstt
heUboat
s.
I
n1929aRussi
anphy
si
ci
st
,Sokol
ov
,exper
i
ment
edwi
t
ht
echni
quesofpassi
ng
v
i
br
at
i
onst
hr
oughmet
al
st
of
i
ndf
l
aws;
t
hi
swor
kwast
akenupbyt
heGer
mans.I
n
t
he1930st
hecat
hoder
ayt
ubewasdev
el
opedandmi
ni
at
ur
i
sedi
nt
heSecond
Wor
l
dWart
of
i
tsmal
lai
r
bor
ner
adarset
si
nt
oai
r
cr
af
t
.I
tmadet
heUTsetaswe
knowi
tpossi
bl
e.Ar
ound1931Mul
hauserobt
ai
nedapat
entf
orasy
st
em usi
ngt
wo
pr
obest
odet
ectf
l
awsi
nsol
i
dsandf
ol
l
owi
ngt
hi
sFi
r
est
one(
1940)andSi
mons
(
1945)dev
el
opedpul
sedUTusi
ngapul
se-echot
echni
que.
I
nt
hey
ear
saf
t
erWor
l
dWarI
I
,r
esear
cher
si
nJapanbegant
oexper
i
mentont
he
useoful
t
r
asoundf
ormedi
caldi
agnost
i
cpur
poses.TheJapaneseWor
ki
ngl
ar
gel
y
i
ni
sol
at
i
onf
r
om t
her
estoft
hewor
l
dunt
i
lt
he1950s,t
heJapanesedev
el
oped
t
echni
quesf
ort
hedet
ect
i
onofgal
l
st
ones,
br
eastmasses,
andt
umor
s.Japanwas
al
sot
hef
i
r
stcount
r
yt
o appl
yDoppl
erul
t
r
asound,anappl
i
cat
i
onoful
t
r
asound
t
hatdet
ect
si
nt
er
nalmov
i
ng obj
ect
ssuchasbl
oodcour
si
ngt
hr
ought
hehear
tf
or
car
di
ov
ascul
ari
nv
est
i
gat
i
on.
Thef
i
r
stf
l
awdet
ect
orwasmadebySpr
oul
ei
n1942whi
l
ehewaswor
ki
ngf
ort
he
Scot
t
i
shf
i
r
m Kel
v
i
n&Hughes.Si
mi
l
arwor
kwascar
r
i
edoutbyFi
r
est
onei
nt
he
USAandbyGer
manphy
si
ci
st
s.Spr
oul
ewentont
odev
el
opt
heshear
wav
epr
obe.
Atf
i
r
st
,UTwasr
est
r
i
ct
edt
ot
est
i
ngai
r
cr
af
t
,buti
nt
he1950si
twasext
ensi
v
el
y
used i
n t
hebui
l
di
ng ofpowerst
at
i
onsi
n Br
i
t
ai
nf
orexami
ni
ng t
hi
ckst
eel
component
ssaf
el
yandcheapl
y
.UTwasf
oundt
ohav
esev
er
aladv
ant
agesov
er
r
adi
ogr
aphyi
nheav
yi
ndust
r
i
al
appl
i
cat
i
ons:
 Di
d nothav
et
heheal
t
h hazar
d associ
at
ed wi
t
hr
adi
ogr
aphy
,and aUT
t
echni
ci
an coul
d wor
k nextt
o wel
der
s and ot
herempl
oy
ees wi
t
hout
endanger
i
ngt
hem orhol
di
ngupwor
k.
 Wasef
f
i
ci
enti
ndet
ect
i
ngt
oecr
acksi
nboi
l
er
s-amaj
orcauseofexpl
osi
ons
andl
ackoff
usi
oni
nboi
l
ert
ubes.
 Foundpl
anardef
ect
s,l
i
kel
ami
nat
i
ons,whi
chwer
esomet
i
mesmi
ssedby
r
adi
ogr
aphy
.
 AUTcheckonat
hi
ckcomponentt
ooknomor
et
i
met
hanasi
mi
l
archeckon
at
hi
ncomponentasopposedt
ol
ongexposur
et
i
mesi
nr
adi
ogr
aphy
.
Wi
t
ht
heconst
r
uct
i
onofnucl
earpowerst
at
i
ons,UTwasdev
el
opedf
ur
t
herand
wasappl
i
edt
oconst
r
uct
i
onandmai
nt
enancewor
ki
nt
heoi
l
i
ndust
r
yaswel
l
ast
he
i
nspect
i
onoft
hehugecommer
ci
alai
rf
l
eet
sbui
l
tupsi
ncet
heendoft
heSecond
Wor
l
dWar
.Ov
ert
hey
ear
s,
UTset
shav
ebeenmi
ni
at
ur
i
sedwi
t
ht
heav
ai
l
abi
l
i
t
yof
t
r
ansi
st
or
sanddi
spl
ayf
eat
ur
esi
mpr
ov
edandt
hepr
ocesshasaut
omat
edand
comput
er
i
sed.
1.
8 Ul
t
r
asoundusedf
ort
est
i
ng
Themai
nuseoful
t
r
asoni
ci
nspect
i
oni
nt
hehumanandt
heani
malwor
l
di
sf
or
det
ect
i
ngobj
ect
sandmeasur
i
ngdi
st
ance.Apul
seoful
t
r
asound(
asqueakf
r
om a
batorapul
sef
r
om anul
t
r
asoni
csour
ce)hi
t
sanobj
ectandi
sr
ef
l
ect
edbackt
oi
t
s
sour
cel
i
keanecho.Fr
om t
het
i
mei
tt
akest
ot
r
av
elt
ot
heobj
ectandback,t
he
di
st
anceoft
heobj
ectf
r
om t
hesoundsour
cecanbecal
cul
at
ed.Thati
showbat
s
f
l
yi
nt
hedar
kand how dol
phi
nsnav
i
gat
et
hr
oughwat
er
.I
ti
sal
sohowwar
shi
ps
det
ect
edandat
t
ackedsubmar
i
nesi
nt
heSecondWor
l
dWar
.Wear
i
ngabl
i
ndf
ol
d,
y
oucandet
er
mi
nei
fy
ouar
ei
nav
er
yl
ar
gehal
loranor
di
nar
yr
oom bycl
appi
ng
y
ourhandsshar
pl
y
;
al
ar
gehal
lwi
l
lgi
v
ebackadi
st
i
nctecho,
butanor
di
nar
yr
oom
wi
l
lnot
.Abat
sechol
ocat
i
oni
smor
epr
eci
se:t
hebatgi
v
esoutandcansense
shor
twav
el
engt
hsoful
t
r
asoundandt
hesegi
v
eashar
perechot
hanwecan
det
ect
.I
nUTasoundpul
sei
ssenti
nt
oasol
i
dobj
ectandanechor
et
ur
nsf
r
om any
f
l
aws i
nt
hatobj
ectorf
r
om t
heot
hersi
deoft
heobj
ect
.Anechoi
sr
et
ur
nedf
r
om
asol
i
dai
ri
nt
er
f
aceoranysol
i
dnonsol
i
di
nt
er
f
acei
nt
heobj
ectbei
ngexami
ned.
Wecansendul
t
r
asoni
cpul
sesi
nt
omat
er
i
albymaki
ngapi
ezoel
ect
r
i
ccr
y
st
al
v
i
br
at
ei
napr
obe.Thepul
sescant
r
av
eli
nacompr
essi
on,shearort
r
ansv
er
se
mode.Thi
si
st
hebasi
s of ul
t
r
asoni
ct
est
i
ng.Butamet
hodmustbef
oundof
pr
esent
i
ngi
nf
or
mat
i
onf
r
om t
he r
et
ur
ni
ngechoesf
ori
nt
er
pr
et
at
i
on.I
ti
sf
ort
hi
s
pur
poset
hatt
heUTset
,orf
l
aw det
ect
orasi
ti
sf
r
equent
l
ycal
l
ed,cont
ai
nsa
cat
hoder
ayt
ube.
I
nt
hemaj
or
i
t
yofUTset
st
hei
nf
or
mat
i
oni
spr
esent
edont
hescr
eeni
nadi
spl
ay
cal
l
edt
heAScan.Thebot
t
om oft
heCRTscr
eeni
sat
i
mebasemadet
or
epr
esent
adi
st
ance-say100mm.Anechof
r
om t
hebackwal
lcomesupont
hescr
eenasa
si
gnal
,t
heampl
i
t
udeofwhi
chr
epr
esent
st
heamountofsoundr
et
ur
ni
ngt
ot
he
pr
obe.Byseei
nghowf
art
hesi
gnalcomesal
ongt
hescr
eenwecanmeasur
et
he
t
hi
cknessoft
hemat
er
i
al
wear
eexami
ni
ng.
I
ft
hatmat
er
i
alcont
ai
nsaf
l
awsoundi
sr
ef
l
ect
edbackf
r
om t
hef
l
awandappear
s
ont
hescr
eenasasi
gnali
nf
r
ontoft
hebackwal
lechoast
hesoundr
ef
l
ect
edf
r
om
t
hef
l
awhas nothadsof
art
ot
r
av
el
ast
hatf
r
om t
hebackwal
l
.
Any
t
hi
ngt
hatsendsbacksoundener
gyt
opr
obet
ocauseasi
gnal
ont
hescr
een
i
scal
l
edar
ef
l
ect
or
.Bymeasur
i
ngt
hedi
st
ancef
r
om t
heedgeoft
heCRTscr
een
t
ot
hesi
gnal
,
wecancal
cul
at
ehowf
ardowni
nt
hemat
er
i
al
t
her
ef
l
ect
orl
i
es.
2 Basi
cPr
i
nci
pl
esofSound
Soundi
smadewhensomet
hi
ngv
i
br
at
es.Youcant
wangar
ul
eronat
abl
eorf
l
i
ck
ast
r
et
chedel
ast
i
cbandt
ov
er
i
f
yt
hi
s.Thest
r
et
chedsur
f
aceoft
her
ubberbandor
t
her
ul
erv
i
br
at
esandset
supaser
i
esofv
i
br
at
i
ons,
soundwav
es,
i
nt
heai
r
.Ast
he
sur
f
aceoft
hebandorr
ul
erpushesi
nt
ot
heai
r
,t
heai
rmol
ecul
esar
ef
or
ced
t
oget
herandar
egi
onofhi
ghpr
essur
ef
or
ms:compr
essi
on.Ast
hesur
f
acemov
es
back,
t
heai
rmol
ecul
esmov
eapar
t
,
f
or
mi
ngal
owpr
essur
ear
ea,
orr
ar
ef
act
i
on.As
t
hesur
f
acev
i
br
at
es,al
t
er
nat
ecompr
essi
onsar
er
ar
ef
act
i
onssetupi
nt
heai
rand
t
r
av
eloutf
r
om t
hesur
f
acet
of
or
m asoundwav
e.Theai
rmol
ecul
esdon’
tmov
e
wi
t
ht
hewav
e-t
heyv
i
br
at
et
oandf
r
oi
nt
i
mewi
t
ht
hev
i
br
at
i
ngsur
f
ace.I
fwepl
ot
t
hedi
spl
acementoft
hepar
t
i
cl
eagai
nstt
i
mei
twi
l
lpr
oduceasi
newav
easshown
bel
ow.
The sound wav
e so pr
oduced t
r
av
el
st
hr
ough t
he ai
rata speed of
332m/
sec,at 0˚
C.Weheart
hesoundwheni
thi
t
samembr
anei
nourearand
causei
tt
ov
i
br
at
e.Soundwi
l
lt
r
av
elt
hr
oughanymedi
um t
hathasmol
ecul
est
o
mov
e,buti
tt
r
av
el
sf
ast
eri
nmor
eel
ast
i
cmat
er
i
al
sbecauset
hev
i
br
at
i
onsar
e
passedonmor
equi
ckl
y
.Soundt
r
av
el
sf
ast
eri
nwat
erormet
alt
hani
tdoesi
nai
r
asl
i
qui
dsandsol
i
dsar
emor
eel
ast
i
ct
hanai
r
.
2.
1 Fr
equency
Assoundi
saser
i
esofv
i
br
at
i
ons,
onewayofmeasur
i
ngi
ti
st
ocountt
henumber
ofv
i
br
at
i
onspersecond-t
hef
r
equency
.Fr
equencyi
smeasur
edi
nHer
t
z.One
v
i
br
at
i
oni
nonesecondi
soneHer
t
z.Twov
i
br
at
i
onsi
nonesecondi
st
woHer
t
z.
Tenv
i
br
at
i
onsi
nonesecondi
s10Her
t
zand1000v
i
br
at
i
onsi
nonesecond i
s
1000Her
t
zoroneki
l
oher
t
z (
kHz)
.Onemi
l
l
i
onv
i
br
at
i
onsi
nasecondi
sone
Megaher
t
z(
MHz)
.
Thehi
ghert
hef
r
equencyt
hehi
ghert
henot
esounds-t
hehi
ghert
hepi
t
ch.I
fy
ou
t
wang t
her
ul
erort
her
ubberbandhar
d,t
henoi
sei
sl
ouder
,i
thasgr
eat
er
ampl
i
t
ude,butt
henot
er
emai
nst
hesame.I
f
,howev
er
,y
oushor
t
ent
her
ul
eror
t
i
ght
ent
her
ubberband,
t
hey
v
i
br
at
emor
equi
ckl
yandt
henot
egi
v
enouti
shi
gher
.Thef
r
equencyi
sgr
eat
er
.To
r
ai
set
hepi
t
choft
hei
ri
nst
r
ument
,
gui
t
arpl
ay
er
smov
et
hei
rf
i
nger
sdownt
hef
r
et
s,
t
husshor
t
eni
ngt
hest
r
i
ngandmaki
ngi
tv
i
br
at
emor
equi
ckl
y
.Wecanonl
yhear
sounds bet
weencer
t
ai
nf
r
equenci
es-mor
et
han20Her
t
zandl
esst
han20,
000
Her
t
z.I
fy
ouwer
eabl
et
omov
ey
ourar
m upanddown20t
i
mesasecond,
i
twoul
d
soundl
i
keav
er
yl
owhum.Youcannot
,
soy
oucannotheart
hev
i
br
at
i
onsi
nt
heai
r
causedbyy
ourmov
i
ngar
m.Adogwhi
st
l
ev
i
br
at
i
ngat25,
000Her
t
zcannotbe
hear
dbyhumans,
buti
tcanbehear
dbyt
hesensi
t
i
v
eear
sofadog.
Thesoundspect
r
um
I
tr
ar
el
yoccur
st
oust
hatt
her
ei
sawhol
ewor
l
dofsoundt
hatwecannothear
.
Someot
herani
mal
scanhearsoundsathi
gherf
r
equenci
es-bat
scanhearsound
at100,
000Her
t
z
-andsomeani
mal
s,
l
i
kesnakes,
hav
ewor
sehear
i
ngt
hanwehav
e.
A soundwi
t
hf
r
equenci
esabov
et
heupperr
angeofhumanhear
i
ngi
scal
l
ed
ul
t
r
asound.Sound bel
ow about16 Her
t
zi
s cal
l
ed i
nf
r
asound.Ther
ef
or
et
he
def
i
ni
t
i
on oful
t
r
asound i
ssound wi
t
haf
r
equencygr
eat
ert
han 20 ki
l
oher
t
z.
Howev
er
,
t
her
ei
sanadv
ant
agef
ort
hel
owerf
r
equenci
es.Thel
owert
hef
r
equency
,
t
hemor
epenet
r
at
i
ngasoundwav
ei
s-t
hati
swhyf
oghor
nsgi
v
eoutv
er
yl
ow
not
esandwhyt
hel
ow t
hr
obbi
ngnot
esf
r
om y
ournei
ghbour
sst
er
eosetcome
t
hr
ought
hewal
l
r
at
hert
hant
hehi
ghnot
es.
2.
2 Wav
el
engt
h
Awav
ei
nt
heseai
sav
i
br
at
i
onofener
gy
.Ast
hewav
epassesaf
i
xedpoi
nti
t
pr
oducesaconst
antr
i
seandf
al
lofener
gy
.Acompl
et
ev
i
br
at
i
oni
sachangei
n
ener
gyf
r
om maxi
mum t
omi
ni
mum andbackt
omaxi
mum.Thedi
st
anceov
er
whi
chonecompl
et
ev
i
br
at
i
onofener
gyoccur
si
scal
l
edawav
el
engt
h.
Awav
el
engt
hi
st
hedi
st
ancebet
weent
hehi
ghestpoi
nt
sofener
gy
.I
tv
ar
i
eswi
t
h
t
hespeedofsoundandwi
t
ht
hef
r
equency
.Wav
el
engt
hi
sr
epr
esent
edbyt
he
Gr
eekl
et
t
erl
ambda (
λ)
.Wecanwor
koutwav
el
engt
hi
fweknow t
hespeedand
f
r
equencyofasoundwav
e.Wav
el
engt
hi
st
hev
el
oci
t
yi
nmet
er
spersecond
di
v
i
dedbyt
hef
r
equency
.
The wav
el
engt
h oful
t
r
asoni
c wav
es i
si
mpor
t
antbecause t
he shor
t
ert
he
wav
el
engt
h,
t
hesmal
l
ert
hef
l
awst
hatcanbedi
scov
er
ed.Def
ect
sofadi
amet
erof
l
esst
hanhal
fawav
el
engt
hmaynotshow ont
heCRT.Ont
heot
herhand,t
he
shor
t
ert
hewav
el
engt
ht
hel
esst
heul
t
r
asoundwi
l
lpenet
r
at
et
het
estmat
er
i
al
.
Beam shapei
sal
soaf
f
ect
edbywav
el
engt
h.Thesef
act
or
swi
l
l
bedi
scussedl
at
er
.
2.
3 Resol
ut
i
on:
Resol
ut
i
on i
st
he abi
l
i
t
y ofan equi
pment
/
combi
nat
i
on pr
obe t
o di
st
i
ngui
sh
bet
ween t
wo echoes f
r
om r
ef
l
ect
or
st
hatar
e cl
ose t
oget
her
.To hav
e good
r
esol
ut
i
onapr
obemustpr
esentt
wosi
gnal
sonaCRTscr
eenf
r
om t
wosepar
at
e
r
ef
l
ect
or
s:i
fi
thaspoorr
esol
ut
i
ont
heechoesf
r
om t
het
wor
ef
l
ect
or
sappearas
onesi
gnal
ont
hescr
een.
I
nt
heear
l
yday
soful
t
r
asoni
ct
est
i
ngweusedt
he100,
91and85mm st
eps,
att
he
r
adi
usendoft
heV1bl
ockt
ot
estr
esol
v
i
ngpower
.Howev
er
,
t
odayt
hi
si
sr
egar
ded
ast
oocr
ude at
estandBS4331Par
t3(
now obsol
et
e)r
ecommendedt
hatwe
shoul
dbeabl
et
or
ecogni
set
wodi
scr
et
eechoesl
esst
hant
wowav
el
engt
hsapar
t
.
Bydi
scr
et
eechoest
heymeanspl
i
tbymor
et
han6dB,
ort
omor
et
hanhal
ft
het
ot
al
hei
ghtoft
hesi
gnal
s.
2.
4 Si
gnalampl
i
t
ude
Theampl
i
t
udeofanul
t
r
asoni
csi
gnali
sdef
i
nedast
hemaxi
mum di
spl
acementof
t
hemol
ecul
esf
r
om t
hei
requi
l
i
br
i
um posi
t
i
on.Theener
gyofanul
t
r
asoni
cwav
ei
s
i
nt
ur
nexpr
essedast
hesquar
eoft
heampl
i
t
ude.
Ther
el
at
i
v
eampl
i
t
udeoful
t
r
asoni
csi
gnal
si
sexpr
essedusi
ngt
hedeci
bel
,a
l
ogar
i
t
hmi
cuni
tofcompar
i
son.Whenwecompar
et
hehei
ghtoft
wosi
gnal
sont
he
CRTscr
een,
we ar
ei
nf
actcompar
i
ngt
heel
ect
r
i
cv
ol
t
aget
hati
sbei
ngsentt
ot
he
Y pl
at
es,andel
ect
r
i
cv
ol
t
agei
spr
opor
t
i
onalt
ot
hesquar
eoft
hecur
r
ent
.To
compar
et
wosi
gnal
swemustuseaf
or
mul
at
hatt
akesaccountoft
hi
sf
act
:
Di
f
f
er
encei
ndb=
Forexampl
e,i
fwewantt
ocompar
easi
gnalof80mm wi
t
honeof40mm ont
he
CRTscr
een:
Di
f
f
er
encei
ndb=
=
Fi
ndt
he
of2i
nt
abl
esoracal
cul
at
or
20x0.
301=6.
02dB
Sot
heansweri
s6deci
bel
sandt
hi
scanbet
est
edonaCRTscr
een.Obt
ai
nasi
gnal
f
r
om abackwal
lechoonat
estbl
ockandi
ncr
easeordecr
easet
hegai
nunt
i
lt
he
si
gnalt
ouchest
het
opoft
hescr
een.Takeout6dBswi
t
ht
hegai
ncont
r
olandt
he
si
gnalshoul
ddr
opt
o50% f
ul
lscr
eenhei
ght(
FSH)
.I
fi
tdoesnot
,t
hev
er
t
i
cal
l
i
near
i
t
yoft
heUTseti
sout
,t
hesi
gnalhei
ghti
snotchangi
ngi
naccor
dancewi
t
h
ener
gyf
r
om t
hepr
obe.
Usi
ngt
hef
or
mul
a,
wecandi
scov
ert
hat
:
•12dBdi
f
f
er
encemeanst
hatonesi
gnal
i
s4t
i
mesbi
ggert
hananot
her
•10dBdi
f
f
er
encemeanst
hatonesi
gnal
i
s3t
i
mesbi
ggert
hananot
her
•20dBdi
f
f
er
encemeanst
hatonesi
gnal
i
s10t
i
mesbi
ggert
hananot
her
Remembert
hatdBsar
eonl
yameansofcompar
i
ngsi
gnal
s.Al
lUT set
sar
e
di
f
f
er
ent
,soadef
ectmaybeatFSHwi
t
hagai
ncont
r
olr
eadi
ngof
,say36dBon
onesetandbeatFSH onanot
hersetwi
t
hagai
ncont
r
olr
eadi
ngofonl
y28dBon
anot
herset
.TheGai
ncont
r
olal
l
owsust
osetsensi
t
i
v
i
t
i
esandf
or
mst
hebasi
sof
ul
t
r
asoni
csi
zi
ngt
echni
ques.
3ThePr
opagat
i
onofSound
beam
edge
(
0%
hal
fangl
eofdi
v
er
gence
dead
beam cent
r
e
(
(
(
100%
cr
y
st
a
nearzone
f
ar
beam edge
(
0%
TheUl
t
r
asoni
c
3.
1 Deadzone:
Seenont
heCRTasanext
ensi
onoft
hei
ni
t
i
alpul
se,t
hedeadzonei
st
her
i
ngi
ng
t
i
meoft
hecr
y
st
alandi
ti
smi
ni
mi
zedbyt
hedampi
ngmedi
um behi
ndt
hecr
y
st
al
.
Fl
awsorot
herr
ef
l
ect
or
s,l
y
i
ngi
nt
hi
sdeadzoner
egi
onoft
hebeam wi
l
lnotbe
det
ect
ed.Thedead zonecan beseen att
hest
ar
toft
het
r
aceon t
heCRT
di
spl
ay
i
ngAscan,
butonl
ywi
t
hsi
ngl
ecr
y
st
al
pr
obes.
3.
2
NearzoneorFr
esnelzone:
I
nt
hi
sr
egi
on oft
he beam,t
he sound i
nt
ensi
t
yi
sv
ar
i
abl
e owi
ng t
o wav
e
i
nt
er
f
er
ence,t
her
ef
or
e,r
ef
l
ect
or
sorf
l
awsl
y
i
ngi
nt
hi
szonemayappearsmal
l
eror
l
ar
gert
han t
hei
ract
ualsi
ze.The si
gnalhei
ght
s di
spl
ay
ed on t
he CRT ar
e
unpr
edi
ct
abl
esoi
ti
sdesi
r
abl
et
okeept
henearzonel
engt
ht
oami
ni
mum.
Nearzonel
engt
h(
mm)= or
Wher
e;
D=di
amet
eroft
hecr
y
st
al
(
mm)
λ=wav
el
engt
h(
mm)
f=pr
obef
r
equency(
Hz)
v
=t
estmat
er
i
al
v
el
oci
t
y(
mm/
s)v
el
oci
t
ysomet
i
mesdenot
edas‫׳‬
c’
.
I
tcanbeseenf
r
om t
heabov
ef
or
mul
at
hatt
henearzonedecr
easedby
decr
easi
ngcr
y
st
al
di
amet
erand/
ordecr
easi
ngt
hepr
obef
r
equency
.
3.
3 FarzoneorFr
aunhof
f
erzone:
Bey
ondt
henearzonet
hef
arzoneexi
st
s,
i
nt
hi
sr
egi
ont
hebeam di
v
er
gence
occur
s,
r
esul
t
i
ngi
ndecayi
nsoundi
nt
ensi
t
yast
hedi
st
ancef
r
om t
hecr
y
st
al
i
ncr
eased.Forexampl
ej
ustabeam ofl
i
ghtf
r
om t
or
chget
sweakert
hef
ur
t
heri
t
t
r
av
el
s.Theamountofbeam di
v
er
gencedependsupont
hecr
y
st
al
di
amet
erand
pr
obef
r
equency
.
Beam di
v
er
gence
Angl
eofbeam di
v
er
gence;
Si
nθ/
2= or
Wher
e;
θ/
2=hal
fbeam spr
eadangl
e, Not
e:
Kf
act
or
s,
K=aconst
ant
Ext
r
emeedge(
0%i
nt
ensi
t
y
)=
el
engt
h(
mm)
6dBor50%i
nt
ensi
t
yedge=
1.
22 =wav
0.
56
D=di
amet
eroft
hecr
y
st
al
(
mm) 20dBor10%i
nt
ensi
t
yedge
=1.
08f=pr
obef
r
equency(
Hz)
v=mat
er
i
al
v
el
oci
t
y
I
tcanbeseenf
r
om t
heabov
ebeam spr
eadf
or
mul
a,
t
hatt
hebeam di
v
er
gencecan
bedecr
easedbyi
ncr
easi
ngt
hecr
y
st
aldi
amet
erori
ncr
easi
ngt
hepr
obef
r
equency
.
Unf
or
t
unat
el
yt
hi
swi
l
lext
endt
hel
engt
hoft
henearzone.Soi
npr
obedesi
gnt
her
e
i
sacompr
omi
set
oobt
ai
nami
ni
mal
beam spr
eadandshor
t
ernearzone.
I
nt
hef
arzoneoft
heul
t
r
asoni
cbeam t
her
ei
snowav
ei
nt
er
f
er
encet
her
ef
or
et
he
soundi
nt
ensi
t
yi
spr
edi
ct
abl
e.Thesoundi
nt
ensi
t
yr
educes100%i
nt
hecent
r
et
o
0% att
heedge oft
hebeam,t
her
ef
or
ewhent
hecent
r
eoft
hebeam hi
t
st
he
r
ef
l
ect
or
/
f
l
aw t
heampl
i
t
udeoft
hesi
gnalont
heCRTwi
l
lbeat maxi
mum.The
soundi
nt
ensi
t
yal
sodecr
easeswi
t
hgr
eat
erdi
st
ancei
tt
r
av
el
s.
D1
D1
D2
Lar
ger
ef
l
ect
or
s
D2
Smal
l
r
ef
l
ect
or
s
A2=
A2=
I
nt
hef
arzonet
heampl
i
t
udeofr
ef
l
ect
edsoundf
r
om l
ar
geandsmal
lr
ef
l
ect
or
s
f
ol
l
owdi
f
f
er
entl
aws.
Lar
geRef
l
ect
or
s(
l
ar
gert
hant
hewi
dt
hoft
heul
t
r
asoni
cbeam)f
ol
l
owt
heI
NVERSE
LAW –Theampl
i
t
udei
si
nv
er
sel
ypr
opor
t
i
onalt
ot
hedi
st
ance,
i
.
e.i
ft
hedi
st
ancei
s
doubl
edt
hent
hesi
gnal
ampl
i
t
udei
shal
v
ed(
i
.
e.r
educed6dB)
.
Smal
lRef
l
ect
or
s Smal
l
ert
han t
he wi
dt
h oft
he ul
t
r
asoni
c beam)f
ol
l
ow t
he
I
NVERSESQUARELAW –Theampl
i
t
udei
si
nv
er
sel
ypr
opor
t
i
onalt
ot
hesquar
eof
t
hedi
st
ance.i
.
e.i
ft
hedi
st
ancei
sdoubl
edt
hent
heampl
i
t
udef
r
om t
hesecond
r
ef
l
ect
ori
sonequar
t
erof t
heampl
i
t
udeoft
henear
er(
i
.
e.r
educed12dB)
.I
ti
s
showni
nt
heabov
ef
i
gur
e.
3.
4 Si
deLobes:
Thesi
del
obesar
esecondar
yl
obest
ot
hepr
i
mar
yul
t
r
asoni
cbeam ormai
nl
obe
t
hatar
ef
or
medatt
hef
aceofat
r
ansducerandr
adi
at
eawayf
r
om t
hemai
nl
obe.
They r
epr
esentar
eas ofhi
gh and l
ow acoust
i
ci
nt
ensi
t
i
es and may cause
unwant
edechoest
ober
ecei
v
ed byt
hepr
obe,especi
al
l
yont
her
oughsur
f
aces,
whi
chmaybemi
st
akenf
orf
l
awsont
heCRT.Forshearwav
epr
obes,
t
hemi
ni
mum
r
ef
r
act
edbeam angl
ei
sappr
ox
i
mat
el
y33˚t
o35˚
,butatt
heser
el
at
i
v
el
yacut
e
angl
es,
si
del
obesmayf
or
medwhi
ch,
al
t
houghusual
l
y
negl
i
gi
bl
e,
maycausespur
i
ousi
ndi
cat
i
onsont
heCRT.Fort
hi
sr
easoni
ti
s
usual
l
ysaf
ert
osett
hemi
ni
mum beam angl
ef
orshearwav
epr
obei
nst
eel
at
40˚
Thenar
r
owert
hemai
nl
obe,
i
.
e.t
hesmal
l
ert
hehal
f–angl
eoft
hebeam,
t
he
weakerandmor
enumer
oust
hesi
del
obes.
3.
5 TheUl
t
r
asoni
cPul
se:
I
namoder
nul
t
r
asoni
cpul
seechof
l
awdet
ect
ort
hepul
seoful
t
r
asoundi
scr
eat
ed
bychar
gi
ngacapaci
t
ori
nt
heci
r
cui
t
r
yt
hensuddenl
yr
el
easi
ngt
hi
schar
geof
el
ect
r
i
calener
gy
,about1Kvt
o 2Kv
,i
nt
ot
hepr
obe.Thi
sel
ect
r
i
calener
gyi
s
conv
er
t
edi
nt
oamechani
calv
i
br
at
i
onbyt
hepi
ezoel
ect
r
i
cpr
obe.Theul
t
r
asoni
c
v
i
br
at
i
onsar
ef
or
medbyt
hecol
l
apseoft
hecr
y
st
alaf
t
ert
heel
ect
r
i
calener
gy
r
emov
ed.Thebehav
i
oroft
hecr
y
st
al
,
oncol
l
apsecanbel
i
nkedt
ot
hebehav
i
orofa
spr
i
ngwheni
ti
sst
r
et
chedt
henr
el
eased. Thespr
i
ngwi
l
lr
et
ur
nt
oi
t
sf
or
mer
shape.Thi
scy
cl
eofexpansi
onandcont
r
act
i
oni
swhatf
or
m ul
t
r
asoni
cpul
se.
Maxi
mum
cr
y
st
a
Or
i
gi
nal
si
ze
t
i
m
Maxi
mum
Rev0December2010
Page18
3.
6 Pul
sel
engt
handDampi
ng
Apul
seoful
t
r
asoundf
r
om api
ez
oel
ect
r
i
ccr
y
st
alhasal
engt
horwi
dt
hofsev
er
al
v
i
br
at
i
onsorwav
el
engt
hs.Wheny
oust
r
i
keabel
li
tcont
i
nuest
or
i
ngf
orsev
er
al
secondsast
hemet
alcont
i
nuest
ov
i
br
at
e.Thev
i
br
at
i
onsgetst
eadi
l
yweakerand
t
hesounddi
esaway
.I
fy
ouputy
ourhandont
hebel
ly
oust
opt
hev
i
br
at
i
onsand
t
hesounddi
esawaymor
equi
ckl
y-y
oudampent
hesound.
Api
ezoel
ect
r
i
ccr
y
st
alcont
i
nuest
ov
i
br
at
eaf
t
eri
ti
shi
tbyanel
ect
r
i
calchar
ge.
Thi
saf
f
ect
ssensi
t
i
v
i
t
y
,ast
hel
ongert
hepul
sel
engt
h,t
hewor
set
her
esol
ut
i
on.I
n
mostpr
obes asl
ugoft
ungst
enl
oadedAr
al
di
t
ei
spl
acedbehi
ndt
hecr
y
st
alt
ocut
downt
her
i
ngi
ngt
i
meandt
oshor
t
ent
hepul
sel
engt
h.Pul
sel
engt
h(
orwi
dt
h)i
s
al
sosomet
i
mescal
l
edwav
et
r
ai
nl
engt
h.EN1330Par
t4whi
chdef
i
nesi
tast
he
l
eadi
ngandt
r
ai
l
i
ngedgesofapul
semeasur
edatadef
i
nedl
ev
elbel
owt
hepeak
ampl
i
t
ude.
Cr
y
st
a
Thel
engt
hofpul
sei
sunaccept
abl
esi
ncei
nor
dert
oshowsepar
at
e,
cl
earr
ef
l
ect
ed
si
gnal
sont
heCRTt
hent
hepul
sesmustbeshor
tandshar
p.Toshor
t
ent
hepul
ses
t
heul
t
r
asoni
ccr
y
st
almustbedampedwi
t
hbacki
ngmedi
um whi
chabsor
bst
he
soundener
gy
,f
orexampl
ei
nmuchsamewayasashockabsor
berf
i
t
t
edt
oa
spr
i
ngonamot
orv
ehi
cl
e
dampenst
hev
i
br
at
i
onoft
hesuspensi
on.I
nt
hi
swayt
hepul
sel
engt
hcanbe
r
educedt
obet
ween3and5cy
cl
es.
3.
7 Pul
seRepet
i
t
i
onFr
equency(
P.
R.
F.
)
:
Thepul
ser
epet
i
t
i
onf
r
equency(
P.
R.
F.
)orpul
sepr
epet
i
t
i
onr
ange (
P.
R.
R.
)i
st
he
number ofpul
sesul
t
r
asoni
cener
gyt
hatl
eav
esf
r
om t
hepr
obei
nagi
v
ent
i
me
(
usual
l
ypersecond)
.TheP.
R.
Fi
ssomet
i
mescal
l
edast
i
mebasef
r
equency
.Each
pul
seofener
gyt
hatl
eav
esf
r
om t
hepr
obemustr
et
ur
nbef
or
et
henextpul
se
l
eav
esot
her
wi
set
heycol
l
i
deseachot
herandcausi
ngghostorspur
i
ousi
ndi
cat
i
on
appearont
heCRT.Thet
i
met
akenbet
weenf
ort
hepul
set
r
av
elf
r
om t
hepr
obeand
r
et
ur
ni
sknownast
r
ansi
tt
i
me.The t
i
me t
akenbet
weenpul
sesl
eav
i
ngf
r
om t
he
pr
obei
sknownascl
ocki
nt
er
v
al
.Ther
ef
or
ei
tcanbest
at
edt
hatt
het
r
ansi
tt
i
me
mustbeshor
t
ert
hant
hecl
ocki
nt
er
v
alorghost
i
ngoccur
s.Pr
act
i
cal
l
yspeaki
ngt
he
cl
ocki
nt
er
v
al
shoul
dbear
oundf
i
v
et
i
mest
het
r
ansi
tt
i
me.
Tr
ansi
tt
i
me(
µsec)=
Cl
ockI
nt
er
v
al
(
sec)=
Cl
ockI
nt
er
v
al
;
Mi
ni
mum =Tr
ansi
tt
i
me;
Pr
act
i
cal
=5XTr
ansi
tt
i
me
4
ModesofPr
opagat
i
on:
Soundwav
espr
opagat
eduet
ot
hev
i
br
at
i
onsorosci
l
l
at
or
ymot
i
onsofpar
t
i
cl
es
wi
t
hi
namat
er
i
al
.Wi
t
hi
naf
r
eel
yv
i
br
at
i
ngmedi
um eachpar
t
i
cl
ei
ssubj
ectt
obot
h
i
ner
t
i
aland el
ast
i
cf
or
ces.Thesef
or
cescausepar
t
i
cl
est
o exhi
bi
tosci
l
l
at
or
y
mot
i
ons.
4.
1 Compr
e
s
s
i
onorl
ongi
t
udi
nal
wav
e
s
:
Pr
obest
hatpr
oduc
ec
ompr
es
s
i
onwav
eswi
l
lnor
mal
l
yhav
e an i
nc
i
dentand
r
ef
r
ac
t
edangl
eof
,
orc
l
os
et
o,
0˚
.
The
s
ewa
v
e
st
r
a
v
e
l
t
hr
oughame
di
um c
aus
i
ng
t
hepar
t
i
c
l
esoft
hemat
er
i
alt
o os
c
i
l
l
at
epar
al
l
elt
ot
hedi
r
ec
t
i
on ofwav
e
pr
opa
ga
t
i
onandc
ons
i
s
tofa
l
t
e
r
na
t
ec
ompr
e
s
s
i
onanddi
l
a
t
i
onpr
e
s
s
ur
ewa
v
e
s
.
Soundt
r
av
el
st
hr
oughai
ri
nt
hecompr
essi
onalmodeat332m/
sec.I
tt
r
av
el
s
t
hr
ough wat
erat1480/
sec,t
hr
ough Per
spex at2730m/
sec,t
hr
ough st
eel
at
5920m/
secandt
hr
oughal
umi
ni
um at6320m/
sec.Soundcanonl
yt
r
av
elt
hr
ough
ai
randwat
eri
nt
hecompr
essi
onalmode.Soundcant
r
av
elt
hr
oughPer
spex,
st
eel
andal
umi
ni
um i
nmodesot
hert
hant
hecompr
essi
onal
modes.
4.
2 ShearorTr
ansv
er
sewav
es:
Par
t
i
cl
esv
i
br
at
eat90°t
ot
hedi
r
ect
i
onofpr
opagat
i
on.I
nt
heshearort
r
ansv
er
se
mode,mol
ecul
esofasol
i
dmov
er
at
herl
i
kebeachbal
l
sf
l
oat
i
ngont
hesur
f
aceof
t
hesea-t
heymov
eupanddownasawav
epasses.Thi
smodet
r
av
el
si
nsol
i
ds
onl
y
.Becausesol
i
dhasr
i
gi
di
t
yaswel
lasel
ast
i
ci
t
y
.Ai
randwat
er
,
l
i
keot
hergases
andl
i
qui
ds,donothav
er
i
gi
di
t
y
.Shearort
r
ansv
er
sewav
escannott
r
av
eli
ngases
ofl
i
qui
dsf
ort
hi
sr
eason.
Thespeedofsoundi
nt
heshearort
r
ansv
er
semodei
sl
esst
hani
ti
si
nt
he
compr
essi
onorl
ongi
t
udi
nalmode.TheShearspeedofsoundi
nst
eeli
s3250
met
er
spersecondandi
nal
umi
ni
um 3130m/
sec.obv
i
ousl
yt
her
ei
snoshearor
t
r
ansv
er
sespeedf
orai
rorwat
er
.
4.
3 Boundar
yWav
e
s
:
The
s
ef
or
msofpr
opa
ga
t
i
onc
a
nonl
yoc
c
urwhe
nas
ol
i
dt
oga
si
nt
e
r
f
a
c
ei
s
pr
e
s
e
nt
.I
ft
he obj
e
c
t
s we
r
ei
mme
r
s
e
d,t
he
s
e mode
s woul
d be f
ul
l
y
a
t
t
e
nua
t
e
d.
4.
4 Ray
l
e
i
ghorSur
f
ac
eWav
e
s
:
Su
r
f
a
c
ewa
v
e
sa
r
ef
or
me
dwh
e
ns
h
e
a
rwa
v
e
sr
e
f
r
a
c
tt
o90°
.Th
ewh
i
pl
i
k
ep
a
r
t
i
c
l
ev
i
b
r
a
t
i
onoft
h
es
h
e
a
rwa
v
ei
sc
on
v
e
r
t
e
di
n
t
oa
ne
l
l
i
p
t
i
c
a
l
mot
i
onbyt
h
ep
a
r
t
i
c
l
e
sc
h
a
n
g
i
n
gd
i
r
e
c
t
i
ona
tt
h
ei
n
t
e
r
f
a
c
ewi
t
ht
h
e
s
u
r
f
a
c
e
.
Th
e
s
ewa
v
e
sa
r
en
otof
t
e
nu
s
e
di
ni
n
d
u
s
t
r
i
a
lN.
D.
T.a
l
t
h
ou
g
ht
h
e
yd
o
h
a
v
es
ome a
p
p
l
i
c
a
t
i
on
si
nt
h
ea
e
r
os
p
a
c
ei
n
d
u
s
t
r
y
.Th
e
i
rmod
e of
p
r
op
a
g
a
t
i
oni
se
l
l
i
p
t
i
c
a
l
a
l
on
gt
h
es
u
r
f
a
c
eofama
t
e
r
i
a
l
,
p
e
n
e
t
r
a
t
i
n
gt
oa
d
e
p
t
hofon
ewa
v
e
l
e
n
g
t
h
.
Th
e
ywi
l
l
f
ol
l
owt
h
ec
on
t
ou
rofas
u
r
f
a
c
ea
n
d
t
h
e
yt
r
a
v
e
l
a
ta
p
p
r
ox
i
ma
t
e
l
y9
0
%t
h
ev
e
l
oc
i
t
yofs
h
e
a
rwa
v
e
s
.
Wh
e
r
es
h
a
r
pc
h
a
n
g
e
si
nc
on
t
ou
roc
c
u
r
,s
u
c
ha
sac
or
n
e
re
d
g
e
,
r
e
f
l
e
c
t
e
de
n
e
r
g
ywi
l
l
r
e
t
u
r
nt
ot
h
ep
r
ob
e
.
1
4.
5 LamporPl
at
eWav
es:
L
a
mborpl
a
t
ewa
v
e
spr
opa
ga
t
ei
nt
hi
npl
a
t
ema
t
e
r
i
a
l
swhe
nt
hepl
a
t
e
t
hi
c
k
ne
s
si
sa
boutt
hes
a
mea
st
hewa
v
e
l
e
ngt
h.
L
a
mborpl
a
t
ewa
v
e
st
r
a
v
e
l
a
tv
e
l
oc
i
t
i
e
s whi
c
hv
a
r
ywi
t
ht
he pl
a
t
et
hi
c
k
ne
s
sa
nd t
he wa
v
e
l
e
ngt
h.
Pa
r
t
i
c
l
emot
i
oni
se
l
l
i
pt
i
c
a
l
,
a
swi
t
hs
ur
f
a
c
ewa
v
e
s
.The
ya
r
eac
ombi
na
t
i
on
ofc
ompr
e
s
s
i
on a
nd s
ur
f
a
c
e ors
he
a
ra
nd s
ur
f
a
c
e wa
v
e
sc
a
us
i
ngt
he
pl
a
t
ema
t
e
r
i
a
l
t
of
l
e
xbyt
ot
a
l
l
ys
a
t
ur
a
t
i
ngt
hema
t
e
r
i
a
l
5. Ul
t
r
asoundgener
at
i
on:
Soundi
scr
eat
edwhensomet
hi
ngv
i
br
at
es.I
ti
sast
r
esswav
eofmechani
cal
ener
gy
.Thef
i
r
stpeopl
et
oobser
v
et
hepi
ezoel
ect
r
i
cef
f
ectwer
et
heCur
i
ebr
ot
her
s
whoobser
v
edi
ti
nquar
t
zcr
y
st
al
s.
5.
1 Thepi
ezoEl
ect
r
i
cEf
f
ect
:
Thepi
ezoel
ect
r
i
cef
f
ectchangesmechani
cal
ener
gyi
nt
oel
ect
r
i
cal
ener
gy
.I
ti
s
r
ev
er
si
bl
e,
soel
ect
r
i
cal
ener
gy-av
ol
t
age-canbechangedi
nt
omechani
cal
ener
gyorsound,
whi
chi
st
her
ev
er
sepi
ezoel
ect
r
i
cef
f
ect
.
5.
2 Pi
ezoel
ect
r
i
ccr
y
st
al
s
Aswehav
esai
dJacquesandPi
er
r
eCur
i
eusedquar
t
zf
ort
hei
rf
i
r
stexper
i
ment
s.Nowaday
s
pol
ar
i
sedcer
ami
csar
eusedi
nst
eadofquar
t
zcr
y
st
al
s.
I
twasl
at
erdi
scov
er
edt
hatbyv
ar
y
i
ngt
het
hi
cknessofcr
y
st
al
sandsubj
ect
i
ngt
hem t
oa
v
ol
t
aget
heycoul
dbemadet
ov
i
br
at
eatdi
f
f
er
entf
r
equenci
es.Fr
equencydependsont
he
t
hi
cknessoft
hepi
ezo-el
ect
r
i
ccr
y
st
al
,
accor
di
ngt
oaf
or
mul
a:
t
=
Wher
e;
t=Cr
y
st
al
t
hi
ckness;
V=Vel
oci
t
yofsoundi
ncr
y
st
al
;
f=Fr
equency
Pol
ar
i
z
e
dc
r
y
s
t
a
l
sar
emadebyhe
a
t
i
nguppowde
r
st
oahi
ght
e
mpe
r
a
t
ur
e
,
pr
e
s
s
i
ngt
he
mi
nt
os
ha
peal
l
owi
ngt
oc
ool
i
nv
e
r
ys
t
r
onge
l
e
c
t
r
i
c
a
l
f
i
e
l
da
ndi
t
wi
l
la
f
f
e
c
t
s t
heat
omi
cs
t
r
uc
t
ur
eoft
hec
r
y
s
t
a
l
.Thel
i
mi
t
at
i
onsofmode
r
n
pol
ar
i
z
e
dc
r
y
s
t
a
l
sa
r
et
ha
tt
he
yha
v
el
ow me
c
hani
c
als
t
r
e
ngt
h,i
.
e
.t
he
ya
r
e
br
i
t
t
l
eandt
he
yha
v
et
e
nde
nc
yt
oa
ge
.Theadv
ant
agehowe
v
e
ri
st
ha
tt
he
y
a
r
ee
x
c
e
l
l
e
ntge
ne
r
at
or
soful
t
r
a
s
ound.
Th
emos
tc
ommonc
r
y
s
t
a
lma
t
e
r
i
a
l
si
nu
s
ea
r
eBa
r
i
u
m Ti
t
a
n
a
t
ea
n
d
L
e
a
dZi
r
c
on
a
t
eTi
t
a
n
a
t
e
.
The
s
ec
r
y
s
t
al
sma
ybeXc
utorYc
utde
pe
ndi
ngonwhi
c
hor
i
e
nt
at
i
ont
he
y
a
r
es
l
i
c
e
d,f
r
om t
hec
r
y
s
t
a
lma
t
e
r
i
a
l
.Thec
r
y
s
t
a
l
sus
e
di
nul
t
r
a
s
oni
ct
e
s
t
i
ng
a
r
eXc
utduet
ot
hemodeofv
i
br
a
t
i
ont
he
ypr
oduc
e(
c
ompr
e
s
s
i
ona
l
)
.Thi
s
me
a
nst
ha
tt
hec
r
y
s
t
a
li
ss
l
i
c
e
dwi
t
hi
t
sma
j
orpl
a
ne (
t
he c
r
y
s
t
a
lf
a
c
e
)
pe
r
pe
ndi
c
ul
art
ot
heXa
x
i
soft
hec
r
y
s
t
a
l
ma
t
e
r
i
a
l
.
5.
3 Adv
ant
ageandLi
mi
t
at
i
onofPi
ez
oel
ect
r
i
ccr
y
st
al
s
Cr
y
s
t
a
l
ma
t
e
r
i
a
l
Adv
a
n
t
a
ge
s
L
i
mi
t
a
t
i
on
s
Qu
a
r
t
zorSi
l
i
c
on
ox
i
d
e(
Si
O3)
Goodwe
a
rr
e
s
i
s
t
a
n
c
e
Re
s
i
s
t
a
n
c
et
oa
g
e
i
n
g
Ne
e
d
sal
otofe
l
e
c
t
r
i
c
a
l
e
n
e
r
g
yt
op
r
od
u
c
es
ma
l
l
a
mou
n
tofUl
t
r
a
s
ou
n
d
I
n
s
ol
u
b
l
ei
nwa
t
e
r
Su
s
c
e
p
t
i
b
l
et
omod
ec
h
a
n
g
e
L
i
t
h
i
u
m Su
l
p
h
a
t
e
(
Li
SO4)
Ah
i
g
hv
ol
t
a
g
en
e
e
dt
og
i
v
e
Ea
s
yt
oc
u
ta
l
l
f
r
e
qu
e
n
c
i
e
s
l
owf
r
e
qu
e
n
c
ys
ou
n
d
u
b
l
ei
nwa
t
e
r
.
Be
s
tr
e
c
e
i
v
e
ra
n
de
a
s
i
l
y Sol
Da
mp
e
d
.
Br
e
a
kEa
s
i
l
ya
n
dDe
c
omp
os
e
t
Ha
sv
e
r
yl
owe
l
e
c
t
r
i
c
a
l a
t
e
mp
e
r
a
t
u
r
e
sa
b
ov
e1
3
0
˚C
I
mp
e
d
a
n
c
e
Doe
sn
ota
g
e
Ha
sv
e
r
yg
oodr
e
s
ol
u
t
i
on
Ba
r
i
um
Ti
t
anat
e(
BaTi
O3)
Be
s
tt
r
a
n
s
mi
t
t
e
ra
n
d
g
oodPi
e
z
oe
l
e
c
t
r
i
c
p
r
op
e
r
t
i
e
s
.
Ma
yb
ep
e
r
f
or
me
dt
o
f
oc
u
sb
e
a
m.
L
e
a
d
Zi
r
c
ona
t
e
(
PbZr
O
3)
Goods
e
n
s
i
t
i
v
i
t
y
.
Goodp
i
e
z
oe
l
e
c
t
r
i
c
p
r
op
e
r
t
i
e
s
.
De
p
ol
a
r
i
z
ea
t1
0
0
˚
Ct
o1
2
0
˚
C,
a
l
t
h
ou
g
hp
i
e
z
oe
l
e
c
t
r
i
c
p
r
op
e
r
t
i
e
sSt
a
r
td
e
g
r
a
d
ea
t
a
r
ou
n
d7
0
˚
C.
De
t
e
r
i
or
a
t
e
sov
e
rap
e
r
i
odof
t
i
me
.
i
l
v
e
r
i
n
g
.
L
e
a
dZi
r
c
ona
t
e
Goodt
r
a
n
s
mi
t
t
e
ra
n
da
l
l Poors
ou
n
dp
r
op
e
r
t
i
e
s
.
Ti
t
anat
e(
PbZr
O3Ti
O3 r
)
6. Fact
or
saf
f
ect
i
ngt
hepr
opagat
i
onofUl
t
r
asound:
Th
ep
r
op
a
g
a
t
i
onofu
l
t
r
a
s
on
i
cwa
v
e
si
nama
t
e
r
i
a
l
i
sd
e
p
e
n
d
e
n
ton
t
h
ed
e
n
s
i
t
ya
n
de
l
a
s
t
i
cp
r
op
e
r
t
i
e
soft
h
a
tma
t
e
r
i
a
l
a
n
dt
h
et
y
p
eof
wa
v
et
r
a
n
s
mi
t
t
e
d
.
Thepr
ac
t
i
c
al
c
ons
i
der
at
i
onswhi
c
hwi
l
l
af
f
ec
tpr
opagat
i
onwi
l
l
i
nc
l
ude:
a)t
het
es
tmat
er
i
al
'
sgr
ai
ns
i
z
e
b)at
t
enuat
i
on(
abs
or
pt
i
onands
c
at
t
eref
f
ec
t
s
)
c)acoust
i
ci
mpedanc
eoft
het
es
tmat
er
i
al
d)char
ac
t
er
i
s
t
i
ci
mpedanc
eofi
nc
l
us
i
ons
e)di
f
f
r
act
i
on
f
)l
ac
kofhomogenei
t
y
g)ani
s
ot
r
opi
cma
t
e
r
i
a
l
s(
Thegr
a
i
nsa
r
er
a
ndom i
nor
i
e
nt
a
t
i
ona
nd10
ha
v
edi
f
f
e
r
e
nte
l
a
s
t
i
cpr
ope
r
t
i
e
si
ndi
f
f
e
r
e
ntdi
r
e
c
t
i
ons
.
)
6.
1Tot
alAt
t
enuat
i
onLoss
At
t
e
nuat
i
oni
sde
f
i
ne
da
st
hel
os
si
ni
nt
e
ns
i
t
yoft
heul
t
r
as
oni
c be
a
m as
i
t pas
s
e
st
hr
ough a ma
t
e
r
i
a
la
nd i
s de
pe
nde
ntupon t
he phy
s
i
c
a
l
pr
ope
r
t
i
e
soft
hema
t
e
r
i
a
l
.
Thet
womai
nc
aus
esofat
t
enuat
i
onar
eSCATTERandABSORPTI
ON
Absor
pt
i
on:
Theat
t
enuat
i
onr
esul
t
i
ngf
r
om t
r
ansf
or
mat
i
onoful
t
r
asoni
cener
gyi
nt
oot
hert
y
pes
ofener
gy(
e.
g.t
her
mal
)
.Occur
sast
hesoundpul
sehi
t
st
hemol
ecul
esoft
het
est
mat
er
i
alandmakest
hem v
i
br
at
e.Theener
gyl
osti
nv
i
br
at
i
ngt
hemol
ecul
est
ur
ns
t
oheat
.Ther
at
eofabsor
pt
i
onv
ar
i
esf
r
om onemat
er
i
alt
oanot
herandev
enf
r
om
onet
y
peofst
eelt
oanot
her
.I
ti
sv
er
yhi
ghi
nPer
spex,
ny
l
onandl
eadandi
sl
owi
n
al
umi
ni
um.
Scat
t
er
:
Randoml
y r
ef
l
ect
ed ener
gy caused by gr
ai
n st
r
uct
ur
e and/
or by smal
l
di
scont
i
nui
t
i
esi
nt
hebeam pat
h.Scat
t
eroccur
sassoundener
gyi
sr
ef
l
ect
edf
r
om
gr
ai
nsi
nt
het
estmat
er
i
al
.Thel
ar
gert
hegr
ai
ns,t
hemor
escat
t
eroccur
s.The
gr
assatt
he bot
t
om oft
he CRT scr
een i
scaused byr
ef
l
ect
i
onsf
r
om gr
ai
n
boundar
i
esi
nt
het
estmat
er
i
al
.Youseemor
egr
assf
r
om casti
r
onorbr
asst
han
f
r
om smal
lgr
ai
nedmat
er
i
al
sl
i
ker
ef
i
nedst
eeloranneal
edal
umi
ni
um.Thel
onger
t
he wav
el
engt
h ofa sound pul
se,t
he l
ess ener
gyi
s scat
t
er
ed. Wher
et
he
wav
el
engt
hi
ssmal
l
ert
hant
hegr
ai
nsi
ze,
asoundpul
sei
sscat
t
er
edv
er
yqui
ckl
y
.I
t
i
sf
ort
hi
sr
easont
hatal
ow f
r
equencypr
obe,wi
t
hi
t
sl
ongerwav
el
engt
h,has
gr
eat
erpenet
r
at
i
oni
nagi
v
enmat
er
i
al
t
hanahi
ghf
r
equencypr
obe.
6.
2 Ac
ou
s
t
i
cI
mpe
da
n
c
e
:
Ac
ous
t
i
ci
mpedanc
e(
Z)i
st
her
es
i
s
t
anc
e ofa mat
er
i
alt
ot
he pas
s
age of
ul
t
r
as
ound.
I
ti
st
hepr
oduc
toft
hemat
er
i
al
dens
i
t
y(
p)ands
oundv
el
oc
i
t
y(
v
)
.
i
.
e
.
Z=ρv
I
ti
s t
he a
c
ous
t
i
c i
mpe
da
nc
e di
f
f
e
r
e
nc
e be
t
we
e
n t
wo di
f
f
e
r
e
nt
ma
t
e
r
i
a
l
s
/
me
di
umswhi
c
hgov
e
r
nst
he i
nt
e
ns
i
t
y oful
t
r
a
s
ound r
e
f
l
e
c
t
e
d
f
r
om t
he i
nt
e
r
f
a
c
e be
t
we
e
nt
he
m.Conv
e
r
s
e
l
y
,
t
hea
mountoful
t
r
a
s
ound
pa
s
s
i
ngf
r
om onema
t
e
r
i
a
lt
oa
not
he
rde
pe
ndsont
hi
sdi
f
f
e
r
e
nc
ebe
t
we
e
n
t
het
womat
e
r
i
al
s
.
Thi
sdi
f
f
e
r
e
nc
ei
se
x
pr
e
s
s
e
dast
heac
ous
t
i
ci
mpe
da
nc
e
r
a
t
i
o.
The
or
e
t
i
c
al
l
yi
fa
nul
t
r
a
s
oni
cwa
v
ewa
spa
s
s
e
dt
hr
ought
womat
e
r
i
al
s
,
wi
t
ht
hes
amea
c
ous
t
i
ci
mpe
da
nc
e(
1:
1r
a
t
i
o)
,
i
ni
nt
i
ma
t
ec
ont
a
c
t
,
t
he
nno
r
e
f
l
e
c
t
i
onwoul
doc
c
ur
,i
.
e
.100% t
r
a
ns
mi
s
s
i
onofs
oundwoul
doc
c
ur
.I
n
pr
a
c
t
i
c
ei
ti
sv
e
r
ydi
f
f
i
c
ul
tt
oa
c
hi
e
v
ei
nt
i
ma
t
ec
ont
ac
twi
t
houtac
oupl
i
ng
me
di
um (
s
e
ene
x
ts
e
c
t
i
on)
.
TheCoupl
antwoul
dha
v
eadi
f
f
e
r
e
nta
c
ous
t
i
c
i
mpe
da
nc
et
o t
he ma
t
e
r
i
a
la
nds
owoul
da
f
f
e
c
tt
hea
mountofs
ound
r
e
f
l
e
c
t
e
d.
Th
ea
mou
n
tofe
n
e
r
g
yr
e
f
l
e
c
t
e
da
ta
ni
n
t
e
r
f
a
c
ec
a
nc
a
l
c
u
l
a
t
e
dwi
t
ht
h
e
f
ol
l
owi
n
gf
or
mu
l
a
:
Wher
e;
Z1andZ2ar
et
her
es
pec
t
i
v
e
%Ref
l
ec
t
edEner
gy=
mat
er
i
al
s
ac
ous
t
i
ci
mpedanc
eoft
het
wo
I
tc
anbes
eenf
r
om abov
ef
or
mul
at
hat
:
Hi
ghAc
ous
t
i
cI
mpedanc
er
at
i
o(
e.
g.
20:
1)=Mor
eRef
l
ec
t
ed
Ener
gyLowAc
ous
t
i
cI
mpedanc
er
at
i
o(
e.
g.
1:
1)
=Mor
e
t
r
ans
mi
t
t
edEner
gy
I
tc
a
na
l
s
ob
es
e
e
nf
r
om t
h
ef
or
mu
l
at
h
a
tt
h
es
a
mea
mou
n
tofe
n
e
r
g
yi
s
r
e
f
l
e
c
t
e
d
,
r
e
ga
r
dl
e
s
sofwh
i
c
hdi
r
e
c
t
i
ont
h
es
ou
n
di
st
r
a
v
e
l
l
i
n
ga
c
r
os
s
t
h
ei
n
t
e
r
f
a
c
e
.
6.
3 Cou
pl
a
n
t
Be
c
a
u
s
eoft
h
ev
e
r
yh
i
g
ha
c
ou
s
t
i
ci
mpe
da
n
c
er
a
t
i
oofa
i
rt
oas
ol
i
d
ma
t
e
r
i
a
l
a
l
mos
t1
0
0
%oft
h
ee
n
e
r
g
yi
sr
e
f
l
e
c
t
e
da
ta
ni
n
t
e
r
f
a
c
eb
e
t
we
e
n
t
h
e
m (
t
h
eb
a
s
i
soff
l
a
wd
e
t
e
c
t
i
on
)
.Th
e
r
e
f
or
et
oe
n
a
bl
et
h
es
ou
n
d
e
n
e
r
gyt
ot
r
a
n
s
mi
tmor
er
e
a
di
l
yi
n
t
ot
h
et
e
s
ts
p
e
c
i
me
nweh
a
v
et
o
e
x
c
l
u
d
ea
n
ya
i
rt
h
a
tma
yb
ep
r
e
s
e
n
tb
e
t
we
e
nt
h
ep
r
ob
ea
n
dt
e
s
ts
u
r
f
a
c
e
.
Th
i
si
sa
c
h
i
e
v
e
db
ys
u
b
s
t
i
t
u
t
i
n
gt
h
ea
i
rwi
t
hama
t
e
r
i
a
l
t
h
a
th
a
sac
l
os
e
r
a
c
ou
s
t
i
ci
mpe
da
n
c
er
a
t
i
ot
ot
h
ep
r
ob
ea
n
dt
e
s
tma
t
e
r
i
a
l
.Th
i
si
sk
n
own
a
sac
ou
pl
a
n
t
.
Commonc
oupl
a
nt
sa
r
e
:wa
t
e
r
,
oi
l
,
gr
e
a
s
e
,
pol
y
c
e
l
l
,
s
wa
r
f
e
gaa
ndgl
y
c
e
r
i
n
Thes
e
l
e
c
t
i
onofc
oupl
a
nti
ss
ome
t
i
me
sba
s
e
dont
hepos
t
t
e
s
tus
eoft
he
ma
t
e
r
i
a
lbe
i
ngt
e
s
t
e
d,e
.
g.wat
e
rbas
e
dc
oupl
ant
sma
yc
aus
er
us
t
i
ngor
c
or
r
os
i
onbuta
r
ee
a
s
i
e
rt
oc
l
e
a
nof
fi
npr
e
pa
r
a
t
i
onf
orpa
i
nt
i
ngorc
oa
t
i
ng
whe
nc
ompa
r
e
dt
ooi
lorgr
e
a
s
e
,whi
c
hma
ya
c
t
ua
l
l
ypr
ot
e
c
tt
hema
t
e
r
i
a
l
f
r
om c
or
r
os
i
on.
Vi
s
c
o
s
i
t
yo
ft
h
ec
o
u
p
l
a
n
tma
ya
l
s
ob
eac
o
n
s
i
d
e
r
a
t
i
o
n
,
i
d
e
a
l
l
yr
o
u
g
h
s
u
r
f
a
c
e
sr
e
q
u
i
r
eamo
r
ev
i
s
c
o
u
sc
o
u
p
l
a
n
tt
oe
f
f
e
c
t
i
v
e
l
yf
i
l
lt
h
ea
i
r
g
a
p
s mo
r
e u
n
i
f
o
r
ml
y
. Wh
a
t
e
v
e
r c
o
u
p
l
a
n
t i
s u
s
e
d f
o
r
c
a
l
i
b
r
a
t
i
o
n
/
s
e
t
t
i
n
g t
h
e s
e
a
r
c
h s
e
n
s
i
t
i
v
i
t
y
,t
h
i
s mu
s
tb
e u
s
e
d
t
h
r
o
u
g
h
o
u
t
t
h
es
u
b
s
e
q
u
e
n
t
i
n
s
p
e
c
t
i
o
n
.
The i
de
a
la
c
ous
t
i
ci
mpe
da
nc
e ofCoupl
a
nts
houl
d be i
n be
t
we
e
nt
he
a
c
ous
t
i
ci
mpe
da
nc
eoft
hepr
obea
ndt
hea
c
ous
t
i
ci
mpe
danc
eoft
het
e
s
t
ma
t
e
r
i
a
l
.
Thei
de
a
l
t
hi
c
k
ne
s
soft
hel
a
y
e
rofc
oupl
a
nts
houl
dbeonequa
r
t
e
r
oft
hewa
v
e
l
e
ngt
hofs
oundt
hr
oughi
t
.
7 TheDeci
bel
(
DB)
Thedec
i
bel
i
sal
ogar
i
t
hmi
cbas
euni
tus
edt
oc
ompar
es
oundi
nt
ens
i
t
i
es
.
Be
c
aus
ewedonotk
nowt
hea
c
t
ua
le
ne
r
gybe
i
ngt
r
ans
mi
t
t
e
dbyapr
obe
,
wec
anonl
yc
ompa
r
es
oundi
nt
e
ns
i
t
i
e
sbe
i
ngr
e
c
e
i
v
e
da
nde
x
pr
e
s
st
he
m
a
sar
a
t
i
o,
e
.
g.
t
wi
c
ea
smuc
h,
t
e
nt
i
me
sa
smuc
he
t
c
.
.
Ac
ha
nge i
ns
ound i
nt
e
ns
i
t
y
,e
x
pr
e
s
s
e
di
n dB,c
a
n be me
a
s
ur
e
d by
c
ompa
r
i
ngs
i
gna
lhe
i
ght
sonac
a
l
i
br
a
t
e
dCRT.Thec
ha
ngei
ndBi
sgi
v
e
n
byt
hef
or
mul
a
:
dB=20
Wher
eHI
andH2ar
et
her
es
pec
t
i
v
es
i
gnal
hei
ght
s
.
Byt
r
a
n
s
p
os
i
n
gt
h
ef
or
mu
l
ai
ti
sp
os
s
i
b
l
et
od
e
t
e
r
mi
n
et
h
er
a
t
i
ooft
h
e
s
i
g
n
a
l
h
e
i
g
h
t
swh
e
nt
h
ed
Bd
i
f
f
e
r
e
n
c
ei
sk
n
own
.
Thega
i
n/
a
t
t
e
nua
t
orc
ont
r
ol
sonac
onv
e
nt
i
ona
lul
t
r
a
s
oni
cf
l
a
w de
t
e
c
t
or
a
r
ec
a
l
i
br
a
t
e
di
nde
c
i
be
l
s
,i
.
e
.i
fwer
e
duc
et
hei
nt
e
ns
i
t
yoful
t
r
a
s
oundby
6dBa
nys
i
gna
l
ont
heCRTwi
l
l
dr
opt
oha
l
fi
t
sor
i
gi
na
l
he
i
ght
.I
fwer
e
duc
e
ori
nc
r
e
a
s
et
hei
nt
e
ns
i
t
yby20dBt
he
nt
hes
i
gna
lwi
l
lr
e
duc
et
oat
e
nt
hor
i
nc
r
e
as
ebyt
e
nt
i
me
si
t
sor
i
gi
nal
he
i
ghtr
e
s
pe
c
t
i
v
e
l
y
.
I
ti
si
mpor
t
antt
o not
et
ha
ton c
e
r
t
a
i
nf
l
a
w de
t
e
c
t
or
s
,i
fr
e
j
e
c
tor
s
uppr
e
s
s
i
oni
sus
e
dt
or
e
mov
es
ma
l
lunwa
nt
e
ds
i
gna
l
sf
r
om t
he di
s
pl
a
y
,
t
he
nt
hel
i
ne
a
r
i
t
yof t
hea
mpl
i
f
i
e
r
,a
ndhe
nc
et
heot
he
rs
i
gnal
swi
l
lbe
a
dv
e
r
s
e
l
yaf
f
e
c
t
e
d,
i
.
e
.
a6dBdr
opwi
l
l
notr
e
duc
et
hes
i
gna
l
by50%.
Tabl
eofappr
ox
i
mat
edBdr
ops
:
dB
H2
Dr
op
H1
:
H2
r
a
t
i
o
20
10%
90%
10:
1
14
12
20%
25%
80%
75%
5:
1
4:
1
10
33%
67%
3:
1
6
2
50%
80%
50%
20%
2:
1
5:
4
8
Snel
l
’
sLaw:
Whensoundwav
espassobl
i
quel
y(
notat90o)bet
weenmat
er
i
al
shav
i
ngdi
f
f
er
ent
acoust
i
cv
el
oci
t
i
est
hedi
r
ect
i
onofsoundpr
opagat
i
oni
schangedonpassi
ng
t
hr
ought
hei
nt
er
f
aceandt
hesoundwav
ei
ssai
dt
ohav
ebeenr
ef
r
act
ed.
Li
ghtandsoundar
ebot
hr
ef
r
act
edwhenpassi
ngf
r
om onemedi
um t
oanot
her
wi
t
hdi
f
f
er
entv
el
oci
t
i
esandt
hi
smeanst
hatobj
ect
sseenacr
ossani
nt
er
f
ace
appeart
obeshi
f
t
edr
el
at
i
v
et
owher
et
heyr
eal
l
yar
e.
8.
0 Ref
l
ect
i
on
Ul
t
r
asoni
cwav
esar
er
ef
l
ect
edbyobj
ect
sori
nt
er
f
acespl
acedi
nt
hei
rpat
h.When
st
r
i
ki
ng aspect
acul
ar(
mi
r
r
or–l
i
ke)r
ef
l
ect
ort
heangl
eatwhi
cht
hi
sr
ef
l
ect
i
on
t
akespl
acei
sgov
er
nedbyt
hel
awofr
ef
l
ect
i
on,
whi
chst
at
es:
Angl
eofi
nci
dence(
i
)=Angl
eofr
ef
l
ect
i
on(
r
)
8.
1 Ref
r
act
i
on:
Snel
l
’
sl
awst
at
est
hatt
her
at
i
obet
weensoundspeedi
nt
womat
er
i
al
si
st
hesame
ast
her
at
i
obet
weent
hesi
noft
hei
nci
dentandr
ef
r
act
edangl
es(
measur
edf
ort
he
v
er
t
i
calangl
e)
.I
tequat
est
her
at
i
oofmat
er
i
alv
el
oci
t
i
esv
1andv
2t
ot
her
at
i
oof
t
hesi
nesofi
nci
dentandr
ef
r
act
edangl
es.
I
fwewantt
omakeapr
obet
r
ansmi
t
t
i
ngashearwav
eatacer
t
ai
nangl
e,wehav
e
t
ot
r
ansposet
hi
sf
or
mul
a:
Si
nangl
ei
nci
dence=
Si
nI=
Howev
er
,wi
t
hi
nci
dentangl
esl
esst
han27°
,bot
hcompr
essi
onandshearwav
es
ar
egener
at
edi
nt
hest
eel
.Thi
smakesi
nt
er
pr
et
at
i
onv
er
yconf
usi
ng.Togetashear
wav
eoni
t
sown,t
heangl
eofi
nci
dencemustbemor
et
han27.
4°
,cal
l
edt
hef
i
r
st
cr
i
t
i
calangl
e.Thi
sgi
v
esashearwav
eof33°(
t
hel
owestst
andar
dangl
epr
obe
manuf
act
ur
edi
s35°
)
.
Twosoundmodes
I
ft
hei
nci
dentangl
ei
sabov
e57.
14°
.Theshearwav
ei
sr
epl
acedbyasur
f
acewav
e.
Thi
sangl
ei
scal
l
edt
hesecondcr
i
t
i
cal
angl
e.
Cr
i
t
i
calangl
es
Thel
ar
gestpr
obeangl
ey
oucangetf
r
om manuf
act
ur
er
swi
t
houtaspeci
alor
deri
s
80°
.Soshearwav
esont
hei
rowni
nst
eelar
eonl
ypossi
bl
ewi
t
hi
nci
dentangl
es
bet
ween27.
4and57.
14°
,usi
ngaper
spexwedge.Thi
si
sofcour
sewor
kedoutby
t
hepr
obemanuf
act
ur
er
sandi
tmustbebor
nei
nmi
ndt
hatapr
obewhi
chgi
v
esa
r
ef
r
act
edangl
eof45°i
nst
eel
wi
l
l
gi
v
eadi
f
f
er
entr
ef
r
act
edangl
ei
not
hermat
er
i
al
s.
8.
2 Cr
i
t
i
calangl
ecal
cul
at
i
on:
Snel
l
’
sl
aw canbeusedf
orwor
ki
ngoutcr
i
t
i
calangl
esi
nnonf
er
r
ousmet
al
s.
I
ndeed,i
fwear
ei
mmer
si
onscanni
ngt
hei
nci
dentmat
er
i
ali
swat
er
,soa whol
e
newsetofangl
esneedt
obewor
kedout
.
Thef
i
r
stcr
i
t
i
calangl
ei
st
hei
nci
dentangl
eatwhi
cht
hecompr
essi
onwav
ei
nt
he
t
estmat
er
i
al
i
sgener
at
edat90°
.Sousi
ngSnel
l
’
sl
aw:
=
;
Si
n90=1
Si
nI=
Thesecondcr
i
t
i
calangl
ei
st
hei
nci
dentangl
eatwhi
chashearwav
ei
sgener
at
ed
i
nt
hemat
er
i
al
at90°
.UseSnel
l
’
sl
awagai
n:
=
;
Si
n90=1
Si
nI=
Si
nI=0.
8425;
I=57.
4˚
8.
3 Modeconv
er
si
on:
When sound t
r
av
el
si
n a sol
i
d mat
er
i
al
,one f
or
m ofwav
e ener
gy can be
t
r
ansf
or
medi
nt
oanot
her
.Whenal
ongi
t
udi
nal
wav
est
r
i
kesani
nt
er
f
aceat
anangl
e,someoft
heener
gycancausepar
t
i
cl
emov
ementi
nt
het
r
ansv
er
se
di
r
ect
i
ont
ost
ar
tashear(
t
r
ansv
er
se)wav
e.Thi
sphenomenoni
sr
ef
er
r
edt
oas
mode conv
er
si
on and wi
l
loccurev
er
yt
i
me a wav
e encount
er
s an i
nt
er
f
ace
bet
weenmat
er
i
al
sofdi
f
f
er
entacoust
i
ci
mpedanceandt
hei
nci
dentangl
ei
snotat
90ot
ot
hei
nt
er
f
ace.Modeconv
er
si
oncan,t
her
ef
or
e,causenumer
ousspur
i
ous
i
ndi
cat
i
onst
oar
i
sedur
i
ngani
nspect
i
onwhi
cht
hei
nspect
ormustel
i
mi
nat
e.
8.
4 Di
f
f
r
a
c
t
i
on
:
Thi
soc
c
ur
swhe
ns
oundwa
v
e
spa
s
st
het
i
pofanar
r
ow r
e
f
l
e
c
t
or
.Some
oft
hes
ounds
c
a
t
t
e
r
sof
ft
het
i
pc
a
us
i
ngwa
v
e
si
ndi
f
f
e
r
e
ntdi
r
e
c
t
i
onst
ha
t
r
e
i
nf
or
c
eorc
a
nc
e
loutt
heor
i
gi
nalwa
v
e
s
.Thi
sr
e
s
ul
t
si
nas
e
r
i
e
sofhi
gh
a
ndl
owi
nt
e
ns
i
t
ywa
v
e
sr
adi
at
i
ngoutf
r
om t
het
i
ps
,
gi
v
i
ngt
hei
mpr
e
s
s
i
on
ofs
oundbe
ndi
nga
r
oundt
hee
dge
soft
hede
f
e
c
t
.
9
Equ
i
pme
nt
:
9.
1 Pr
obe
s
:
Thea
ngl
eofa pr
obe us
e
di
n ul
t
r
a
s
oni
ct
e
s
t
i
ng i
s me
as
ur
e
df
r
om a
l
i
ne dr
a
wnpe
r
pe
ndi
c
ul
art
ot
het
e
s
ts
ur
f
a
c
e
.Thi
sl
i
nei
sk
nowna
st
he
nor
ma
l
.A0°pr
obet
he
ni
sonewhi
c
ht
r
a
ns
mi
t
ss
ounda
t90°t
ot
het
e
s
t
s
ur
f
a
c
e
.Al
s
ok
nowna
s anor
ma
lpr
obe
,t
hi
spr
obeus
ua
l
l
yt
r
ans
mi
t
s
c
ompr
e
s
s
i
onalorl
ongi
t
udi
nalwa
v
e
s
.A60°a
ngl
epr
obewoul
dt
r
ans
mi
t
s
ounda
t60°t
ot
henor
mal
,
i
.
e
.30°f
r
om t
hes
ur
f
ac
e
.Themos
tc
ommon
a
ngl
epr
obe
st
r
a
ns
mi
ts
he
a
rwa
v
e
s(
a
l
t
hougha
ngl
e
dc
ompr
e
s
s
i
onpr
obe
s
doe
x
i
s
tf
ors
pe
c
i
a
l
a
ppl
i
c
a
t
i
ons
)a
ndt
hema
nuf
a
c
t
ur
e
r
squot
et
hea
ngl
eof
t
hepr
obef
orus
eonmi
l
ds
t
e
e
l
.
9.
1.
1Twi
nCr
y
s
t
al
pr
obe
:
El
ect
r
i
cal
Cor
k
Backi
ng
Cr
y
st
al
Casi
n
Per
spex
Dou
bl
epr
obe
sh
a
v
et
woc
r
y
s
t
a
l
s
,
on
et
r
a
n
s
mi
t
sa
n
dt
h
eot
h
e
rr
e
c
e
i
v
e
s
u
l
t
r
a
s
ou
n
d.Th
ec
or
ks
e
p
a
r
a
t
ori
nb
e
t
we
e
nt
h
es
h
oe
sp
r
e
v
e
n
t
s"
c
r
os
s
t
a
l
k
"or"
c
h
a
t
t
e
r
"b
e
t
we
e
nt
h
ec
r
y
s
t
a
l
s
.Us
i
n
goi
la
saCou
p
l
a
n
tma
y
e
v
e
n
t
u
a
l
l
yb
r
e
a
kd
own t
h
ea
c
ou
s
t
i
cb
a
r
r
i
e
ra
n
dp
r
od
u
c
es
p
u
r
i
ou
s
s
t
a
n
d
i
n
ge
c
h
oe
sont
h
ed
i
s
p
l
a
y
.
Ha
v
i
n
gs
e
p
a
r
a
t
ec
r
y
s
t
a
l
se
l
i
mi
n
a
t
e
st
h
e
d
e
a
dz
on
e
'on t
h
ed
i
s
p
l
a
y
,e
n
a
b
l
i
n
gt
h
ed
e
t
e
c
t
i
on ofn
e
a
r
s
u
r
f
a
c
e
d
e
f
e
c
t
s
.Th
e
s
ep
r
ob
e
sa
r
et
h
e
r
e
f
or
eu
s
e
f
u
lf
ort
e
s
t
i
n
gt
h
i
ns
e
c
t
i
on
s
,
e
.
g
.t
h
i
c
k
n
e
s
sg
a
u
g
i
n
ga
n
de
x
a
mi
n
i
n
gf
orn
e
a
rs
u
r
f
a
c
ef
l
a
ws
.Th
e
c
r
y
s
t
a
l
sma
yb
ef
oc
u
s
e
dt
og
i
v
eaf
oc
a
lp
oi
n
ta
tt
h
ei
d
e
a
lb
e
a
mp
a
t
h
r
a
n
g
et
obee
x
a
mi
n
e
d
.
9.
1.
2Compr
essi
onalwav
epr
obes:
Compr
essi
on pr
obes gener
at
e compr
essi
onalorl
ongi
t
udi
nalwav
es i
nt
est
mat
er
i
al
sand ar
esomet
i
mescal
l
ednor
mal
degr
eepr
obes.At
y
pi
cal
compr
essi
on
pr
obe compr
i
ses a cr
y
st
ali
n a met
alorpl
ast
i
c housi
ng,wi
t
h wi
r
es f
r
om a
connect
i
onbondedt
oi
t
,whi
ch car
r
yt
heel
ect
r
i
calpul
sef
r
om t
hef
l
aw det
ect
or
andcauset
hecr
y
st
alt
ov
i
br
at
e.Behi
nd t
hecr
y
st
ali
smount
eddampi
ngmat
er
i
al
t
or
est
r
i
ctt
hev
i
br
at
i
onandi
nf
r
onti
sapl
ast
i
cdi
sct
opr
ev
entcr
y
st
al
wear
.
9.
1.
3
Si
ngl
ec
r
y
s
t
al
angl
epr
obe
:
Si
ngl
ec
r
y
s
t
a
lpr
obe
s ha
v
e one c
r
y
s
t
a
lt
ha
tt
r
ans
mi
t
sa
nd r
e
c
e
i
v
e
s
ul
t
r
as
ound.Thef
l
a
wde
t
e
c
t
orc
ont
r
ol
st
hepr
oc
e
s
sbyt
r
ans
mi
t
t
i
ngapul
s
e
ofe
ne
r
gy t
he
ns
wi
t
c
hi
ngt
hec
i
r
c
ui
tt
or
e
c
e
i
v
e
,
l
i
s
t
e
ni
ngf
ora
nyr
e
t
ur
ni
ng
s
ound,i
nbe
t
we
e
npul
s
e
s
.Thec
i
r
c
ui
t
r
yc
a
nbes
wi
t
c
he
dqui
c
k
e
rt
ha
nt
he
c
r
y
s
t
a
l
c
a
nbeda
mpe
d. Sot
her
e
c
e
i
v
e
rpi
c
k
supt
hel
a
s
tf
e
wv
i
br
a
t
i
onsof
t
hec
r
y
s
t
a
l
,
a
si
ts
wi
t
c
he
si
n,a
nddi
s
pl
a
y
st
he
m ont
hes
c
r
e
e
na
st
hede
a
d
z
one
.
Thi
se
l
i
mi
nat
e
st
hepos
s
i
bi
l
i
t
yofde
t
e
c
t
i
ngne
ar
s
ur
f
ac
ede
f
e
c
t
s
.
Angl
epr
obe
sha
v
eaPe
r
s
pe
xs
hoe
,
onwhi
c
ht
hec
r
y
s
t
a
ls
i
t
s
,
t
ha
tc
a
n be
ma
c
hi
ne
dt
oa
nyangl
e
.Thea
ngl
eoft
hewe
dgede
t
e
r
mi
ne
st
heangl
et
ha
t
t
heul
t
r
a
s
ounds
t
r
i
k
e
st
hei
nt
e
r
f
a
c
e(
i
nc
i
de
nta
ngl
e
)
.Thi
si
nt
ur
n,
a
c
c
or
di
ng
t
oSne
l
l
'
sl
a
w,
c
ont
r
ol
st
hea
ngl
et
ha
tt
hes
oundwi
l
lpr
opa
ga
t
et
hr
ought
he
(
r
e
f
r
a
c
t
e
da
ngl
e
)
.
Da
mpi
ngma
t
e
r
i
a
l
t
e
s
tma
t
e
r
i
a
l
ont
heba
c
koft
hec
r
y
s
t
a
l
(
a
l
s
ok
nownasaba
t
r
a
s
oni
cpul
s
e
s
c
k
i
ngs
l
ug)c
ont
r
ol
st
hel
e
ngt
hoft
heul
bya
bs
or
bi
ngt
hes
ounde
ne
r
gy
,
pr
oduc
i
ngs
hor
ts
ha
r
ppul
s
e
s
.
Thel
e
ngt
hof
t
hepul
s
ei
st
hemai
nf
a
c
t
or
i
n de
t
e
r
mi
ni
ng t
her
e
s
ol
ut
i
on oft
he
e
qui
pme
nt
.Themos
tc
ommondampi
ngbac
k
i
ngme
di
um i
sTungs
t
e
n
Ar
a
l
di
t
e
.
SHORTPULSELENGTH/
WI
DTH/
DURATI
ONMEANSGOODRESOLUTI
ON.
9.
1.
4I
mmer
si
onpr
obes:
Theset
y
pesofpr
obesar
edesi
gnedf
orusewher
et
het
estpar
ti
si
mmer
sedi
n
wat
er
.Theyar
et
y
pi
cal
l
yusedi
nsi
deawat
ert
ankoraspar
tofasqui
r
t
erorbubbl
er
sy
st
em i
n scanni
ng appl
i
cat
i
ons.I
mmer
si
on t
r
ansducer
s usual
l
y hav
e an
i
mpedancemat
chi
ngl
ay
ert
hathel
pst
ogetmor
esoundener
gyi
nt
ot
hewat
erand
i
nt
ur
n,i
nt
ot
he componentbei
ng i
nspect
ed.I
mmer
si
on t
r
ansducer
s can be
pur
chasedi
naf
l
at
,cy
l
i
ndr
i
cal
l
yorspher
i
cal
l
yf
ocusedl
ens.Af
ocusedt
r
ansducer
cani
mpr
ov
esensi
t
i
v
i
t
yandaxi
alr
esol
ut
i
onbyconcent
r
at
i
ngt
hesoundener
gyt
oa
smal
l
erar
ea.
9.
1.
5Del
ayl
i
nepr
obes:
Del
ayl
i
nepr
obe,
t
hi
snamei
mpl
i
es,
i
nt
r
oduceat
i
medel
aybet
weent
hegener
at
i
on
oft
hesoundwav
eandt
hear
r
i
v
alofanyr
ef
l
ect
edwav
es.Thi
sal
l
owst
hecr
y
st
alt
o
compl
et
ei
t
st
r
ansmi
ssi
onf
unct
i
onbef
or
ei
tbegi
nst
or
ecei
v
er
et
ur
ni
ngsi
gnal
s.
Del
ayl
i
net
r
ansducer
sar
er
ecommendedf
orappl
i
cat
i
onst
hatr
equi
r
eacont
act
t
r
ansducerwi
t
h good near
sur
f
ace r
esol
ut
i
on and ar
e desi
gned f
oruse i
n
appl
i
cat
i
onssuchashi
ghpr
eci
si
ont
hi
ckness gaugi
ng oft
hi
nmat
er
i
al
sand
l
ami
nat
i
on checks i
n composi
t
e mat
er
i
al
s.They ar
e al
so usef
uli
n hi
ght
emper
at
ur
e measur
ementappl
i
cat
i
ons si
nce t
he del
ay l
i
ne pr
ov
i
des some
i
nsul
at
i
ont
ot
hepi
ezoel
ect
r
i
cel
ementf
r
om t
heheat
.
9.
1.
6Whe
e
l
t
y
pepr
obe
:
I
nt
hi
spr
obet
hec
r
y
s
t
ali
swi
t
hi
nt
hea
x
l
eoft
hewhe
e
la
ndt
hes
ound
t
r
a
v
e
l
st
hr
ought
hes
of
tt
y
r
ei
nt
ot
het
e
s
tma
t
e
r
i
a
l
.Thes
pr
i
ngl
oade
dj
oi
nt
a
l
l
owst
he pr
obet
of
ol
l
owt
hec
ont
ouroft
hes
ur
f
a
c
es
oi
tc
a
nbeus
e
don
r
oughorune
v
e
ns
ur
f
ac
e
s
.I
ti
sus
e
di
n40as
i
mi
l
a
rwa
yt
ot
hewa
t
e
rga
p
pr
obe
.Thema
i
na
dv
a
nt
a
geoft
hi
st
y
peofpr
obei
st
ha
ti
tr
e
mov
e
st
he
r
e
qui
r
e
me
ntofe
x
t
e
r
na
l
l
ya
ppl
i
e
dc
oupl
a
nt
,ma
i
nl
y us
e
di
na
e
r
os
pa
c
e
i
ndus
t
r
i
e
s
.
9.
1.
7Wa
t
e
rga
porga
ps
c
a
n
n
i
n
gpr
obe
:
Thi
sc
ons
i
s
t
sofawa
t
e
rj
a
c
k
e
twi
t
hanoz
z
l
ea
tt
hee
nda
ndapr
obei
ns
i
de
.
Wa
t
e
ri
sf
e
di
nt
ot
hej
ac
k
e
tandf
l
owsoutt
hr
ought
henoz
z
l
e
,f
or
mi
nga
c
ol
umnofwat
e
r
,t
ot
het
e
s
ts
ur
f
a
c
e
,t
hr
oughwhi
c
ht
hes
oundc
a
nt
r
a
v
e
l
.
hec
oupl
i
ng90me
Be
c
aus
eoft
hef
l
e
x
i
bi
l
i
t
yoft
di
um,
(
wa
t
e
r
)t
hepr
obec
a
n
beus
e
donr
oughorune
v
e
ns
r
eus
ua
l
l
yus
e
di
n
ur
f
a
c
e
s
.The
s
epr
obe
sa
aut
omat
e
dul
t
r
a
s
oni
cs
c
anni
ng s
y
s
t
e
msa
ndc
a
nbes
e
tup,
us
i
ngagui
de
whe
e
lt
of
ol
l
ow t
hec
ont
ourofac
ompone
nt
.The
yc
a
na
l
s
obeus
e
di
n
a
r
r
a
y
st
os
c
a
nawi
de
ra
r
e
a
.
9.
1.
8Magnet
ost
r
i
ct
i
v
eorEl
ect
r
omagnet
i
cacoust
i
c
Tr
ansducer
s(
EMATs)
:
Af
eat
ur
eofpr
obesusi
ngpi
ezoel
ect
r
i
ccr
y
st
al
si
st
hatt
heyr
equi
r
emechani
cal
coupl
i
ngbet
weent
hemsel
v
esandt
hesol
i
dunderi
nspect
i
on.Thi
si
sachi
ev
ed
ei
t
herbyi
mmer
si
ngt
hem i
nat
ankf
i
l
l
edwi
t
haf
l
ui
d(
usual
l
ywat
er
)ordi
r
ect
l
yby
t
heuseofat
hi
n(
l
esst
hanonequar
t
eroft
hewav
el
engt
h)f
l
ui
dl
ay
erbet
weent
he
t
wo.Whenshearwav
esar
et
obet
r
ansmi
t
t
ed,
t
hef
l
ui
di
sal
sogener
al
l
ysel
ect
edt
o
hav
easi
gni
f
i
cantv
i
scosi
t
y
.Theacoust
i
ci
mpedanceoft
hecoupl
antl
ay
ershoul
d
al
sohav
eav
al
uesomewher
ebet
weent
hatoft
hepr
obeandt
hemat
er
i
albei
ng
t
est
ed.El
ect
r
omagnet
i
cacoust
i
ct
r
ansducer
s(
EMATs)r
el
yuponat
ot
al
l
ydi
f
f
er
ent
phy
si
calpr
i
nci
pl
e.When a wi
r
ei
s pl
aced neart
he sur
f
ace ofan el
ect
r
i
cal
l
y
conduct
i
ngobj
ectandacur
r
entoft
her
equi
r
edul
t
r
asoni
cf
r
equencyi
sappl
i
ed,
eddycur
r
ent
swi
l
lbei
nducedi
nanear
sur
f
acer
egi
onoft
heobj
ect
.EMATpr
obes
ar
e usedf
ort
hedet
ect
i
onoff
l
awsandt
hedet
er
mi
nat
i
onofmat
er
i
alpr
oper
t
i
es
suchaspr
eci
sev
el
oci
t
yorat
t
enuat
i
onmeasur
ement
.Theydonotr
equi
r
et
heuse
ofcoupl
antandassuchcanoper
at
ewi
t
houtcont
actatel
ev
at
edt
emper
at
ur
esand
i
nr
emot
el
ocat
i
ons.
EMATpr
obesar
e,
howev
er
,
i
nef
f
i
ci
entandr
equi
r
est
r
ongmagnet
i
cf
i
el
dsandl
ar
ge
cur
r
ent
st
opr
oduceul
t
r
asoundt
hati
sof
t
enweakert
hant
hatpr
oducedbypi
ezoel
ect
r
i
c t
r
ansducer
s. Rar
eear
t
h mat
er
i
al
s such as samar
i
umcobal
t and
neody
mi
umi
r
onbor
onar
eof
t
enused t
o pr
oducesuf
f
i
ci
ent
l
yst
r
ong magnet
i
c
f
i
el
ds,
whi
chmayal
sobegener
at
edbypul
sedel
ect
r
omagnet
s.
Us
e
df
orde
t
e
c
t
i
ngde
f
e
c
t
i
v
eba
rs
t
oc
k
,
t
het
r
a
ns
duc
e
rc
oi
l
ha
sa ma
gne
t
i
c
f
i
e
l
dt
ha
ti
ss
wi
t
c
hi
nga
tul
t
r
a
s
oni
cf
r
e
que
nc
y
.Thi
sf
i
e
l
dc
aus
e
st
heba
r
s
t
oc
kt
ov
i
br
a
t
ea
ta
nul
t
r
a
s
oni
cf
r
e
que
nc
ya
ndt
he v
i
br
a
t
i
onst
r
a
v
e
la
l
ong
t
he l
e
ngt
h oft
heba
r
.Whe
nt
hev
i
br
a
t
i
onsr
e
a
c
ht
heot
he
re
ndoft
heba
r
,
t
he
yr
e
f
l
e
c
tba
c
k a
nda
r
et
he
npi
c
k
e
dupbyt
het
r
a
ns
duc
e
r(
i
nr
e
c
e
i
v
e
mode
) and r
e
gi
s
t
e
r ont
hede
t
e
c
t
or
.Thee
qui
pme
nti
sc
a
l
i
br
a
t
e
dof
fa
de
f
e
c
tf
r
e
epi
e
c
eofba
rs
t
oc
kt
or
e
gi
s
t
e
ras
pe
c
i
f
i
cv
a
l
ueont
hede
t
e
c
t
or
a
ndde
f
e
c
t
i
v
eba
rs
t
oc
ki
sr
e
c
ogni
z
e
dbyac
ha
ngei
nt
hi
sv
a
l
ue
.
9.
2 Pr
obeF
r
e
qu
e
n
c
y
,
Ba
n
dwi
dt
h&Da
mpi
n
g:
Anul
t
r
a
s
oni
cpr
obet
r
a
ns
mi
t
ss
ounda
tar
a
ngeoff
r
e
que
nc
i
e
s
,
notj
us
ta
t
t
hes
t
a
t
e
df
r
e
que
nc
y
,
t
hi
si
sk
nowna
st
heba
ndwi
dt
h.
Fore
x
a
mpl
ea5MHz
pr
obema
ypr
oduc
eaf
r
e
que
nc
yr
a
ngeof4t
o6MHz
.
Thebandwi
dt
hi
sa
l
s
o
a
ni
ndi
c
a
t
i
onoft
heda
mpi
ngf
ac
t
or
.
Br
oa
dBa
n
dPr
ob
e
s
Na
r
r
owBa
n
dPr
ob
e
s
Theyar
ehi
ghl
ydamped
Theyhav
el
owdampi
ng
As
hor
tr
i
ngi
ngt
i
me(
dead
z
one)
Hav
eas
hor
tpul
s
el
engt
h
Al
ongr
i
ngi
ngt
i
me(
de
a
d
z
one
)
Ha
v
eal
onge
rpul
s
el
e
ngt
h
(
t
y
pi
c
al
l
y3or4
c
y
c
l
e
s
)Poor
r
esol
ut
i
on
Goodpenet
r
at
i
on
(
t
y
pi
cal
l
y1t
o2cy
cl
es)
Bet
t
err
es
ol
v
i
ngpower
Poorpenet
r
at
i
on
9.
2.
1Pr
ob
eSe
l
e
c
t
i
on
Th
es
e
l
e
c
t
i
on ofpr
obe
sf
oru
l
t
r
a
s
on
i
ci
n
s
pe
c
t
i
on i
si
n
f
l
u
e
n
c
e
db
y
v
a
r
i
ou
sa
s
pe
c
t
soft
h
et
e
s
ta
n
dt
h
ep
a
r
t
i
c
u
l
a
rma
t
e
r
i
a
l
u
n
d
e
rt
e
s
t
.
Th
e
s
e
ma
yi
n
c
l
u
d
e
;t
h
et
y
p
ea
n
ds
i
z
eofd
e
f
e
c
tbe
i
n
gs
ou
g
h
t
,t
h
et
y
p
eof
ma
t
e
r
i
a
l
u
n
d
e
rt
e
s
ta
n
dt
h
ed
i
s
t
a
n
c
et
h
es
ou
n
dh
a
st
ot
r
a
v
e
l
t
h
r
ou
g
ht
h
e
ma
t
e
r
i
a
l
.Pr
ob
ea
n
g
l
ei
sa
n
ot
h
e
rc
on
s
i
d
e
r
a
t
i
on wh
e
ns
e
a
r
c
h
i
n
gf
or
d
e
f
e
c
t
sa
td
i
f
f
e
r
e
n
tor
i
e
n
t
a
t
i
on
st
h
r
ou
g
h
ou
tt
h
ema
t
e
r
i
a
l
.
Be
l
ow i
sat
a
b
l
eofp
r
op
e
r
t
i
e
sofp
r
ob
e
su
s
i
n
gt
h
et
woc
r
i
t
e
r
i
at
h
a
twe
c
a
ns
e
l
e
c
t
,
i
.
e
.
f
r
e
qu
e
n
c
ya
n
dd
i
a
me
t
e
r
.
Ef
f
e
c
t
soff
r
e
que
nc
y
L
owF
r
e
qu
e
n
c
y
Hi
g
hF
r
e
qu
e
n
c
y
L
on
gWa
v
e
l
e
n
g
t
h
Mor
eb
e
a
ms
p
r
e
a
d
Sh
or
t
e
rn
e
a
rz
on
e
Be
t
t
e
rp
e
n
e
t
r
a
t
i
on
L
e
s
sa
t
t
e
n
u
a
t
i
on
L
e
s
ss
e
n
s
i
t
i
v
i
t
y
L
on
g
e
rd
e
a
dz
on
e
Sh
or
twa
v
e
l
e
n
g
t
h
L
e
s
sb
e
a
ms
p
r
e
a
d
L
on
g
e
rn
e
a
rz
on
e
L
e
s
sp
e
n
e
t
r
a
t
i
on
Mor
ea
t
t
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n
u
a
t
i
on
Hi
g
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e
rs
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n
s
i
t
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v
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t
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Sh
or
t
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rd
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dz
on
e
Ef
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c
t
sofDi
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me
t
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r
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a
r
g
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a
me
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r
Sma
l
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r
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Mor
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r
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or
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rz
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Be
t
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t
r
a
t
i
on
L
e
s
sa
t
t
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n
u
a
t
i
on
Di
f
f
i
c
ul
tc
oupl
i
ngonc
ur
v
ed
Sur
f
ac
es
Mor
ec
ov
er
ageonf
l
ats
ur
f
ac
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L
e
s
sp
e
n
e
t
r
a
t
i
on
Mor
ea
t
t
e
n
u
a
t
i
on
Ea
s
i
e
rc
ou
p
l
i
n
gonCu
r
v
e
d
Su
r
f
a
c
e
s
Les
sc
ov
er
ageonf
l
ats
ur
f
ac
es
Anot
he
rc
ons
i
de
r
a
t
i
oni
swhe
t
he
rt
ous
eas
i
ngl
ec
r
y
s
t
a
lorac
ombi
ne
d
doubl
ec
r
y
s
t
a
l
pr
obe
.
Thea
dv
a
nt
a
ge
sofas
i
ngl
ec
r
y
s
t
a
l
pr
obe a
r
e
;
be
t
t
e
r
pe
ne
t
r
a
t
i
on,f
ort
hes
a
mes
i
z
epr
obea
sadoubl
e
,be
c
a
us
et
hee
f
f
e
c
t
i
v
e
t
r
a
ns
mi
t
t
e
rc
r
y
s
t
a
ldi
ame
t
e
ri
sl
ar
ge
r
,no f
oc
a
lpoi
nt
,i
.
e
.i
twor
k
s
e
f
f
e
c
t
i
v
e
l
yov
e
ral
onge
rr
a
nge a
ndc
os
t(
c
he
a
pe
r
)
.Thema
i
na
dv
a
nt
a
ge
ofa doubl
ec
r
y
s
t
a
lpr
obe
,i
st
ha
tt
he
r
e i
snode
a
dz
oneont
hes
c
r
e
e
n,
t
hi
sme
a
nsbe
t
t
e
rne
a
rs
ur
f
a
c
er
e
s
ol
ut
i
onc
a
nbea
c
hi
e
v
e
d.
I
tc
a
nbes
e
e
nf
r
om t
het
abl
e
st
ha
thi
ghe
rf
r
e
que
nc
ypr
obe
sha
v
eahi
ghe
r
s
e
ns
i
t
i
v
i
t
y
.I
nt
hi
sc
ont
e
x
t
,s
e
ns
i
t
i
v
i
t
yr
e
f
e
r
st
ot
hea
bi
l
i
t
yt
ode
t
e
c
ts
ma
l
l
de
f
e
c
t
s
.Thehi
ghe
rt
hepr
obef
r
e
que
nc
yt
hes
ma
l
l
e
rt
hewa
v
e
l
e
ngt
ha
nd
t
hes
ma
l
l
e
rt
hes
i
z
eofr
e
f
l
e
c
t
ort
hepr
obe c
a
n de
t
e
c
t
.I
ti
s ge
ne
r
a
l
l
y
a
c
c
e
pt
e
d t
ha
tt
he s
ma
l
l
e
s
tr
e
f
l
e
c
t
orapr
obec
a
nde
t
e
c
ti
s ha
l
ft
he
pr
obe
'
swa
v
e
l
e
ngt
h.Soapr
obewi
t
hal
ongwa
v
e
l
e
ngt
h(
l
ow f
r
e
que
nc
y
)
wi
l
l not de
t
e
c
t s
ma
l
l r
e
f
l
e
c
t
or
s
,s
uc
ha
ss
ma
l
lde
f
e
c
t
s orgr
a
i
n
bounda
r
i
e
sa
nds
ot
hes
oundwi
l
lpe
ne
t
r
a
t
ef
ur
t
he
rt
hr
ought
hema
t
e
r
i
a
l
be
c
a
us
ei
ti
snotr
e
f
l
e
c
t
e
da
tt
he
s
es
ma
l
l
i
nt
e
r
f
a
c
e
s
.
9.
3
TheUl
t
r
asoni
cFl
awdet
ect
or
:
9.
3.
1 Pr
i
nci
pl
es
Theul
t
r
asoni
cf
l
aw det
ect
or
,t
heUTset
,sendsav
ol
t
agedownacoaxi
alcabl
e,
somet
i
mescal
l
edt
hel
eadt
oapr
obe.Thepi
ezoel
ect
r
i
ccr
y
st
ali
nt
hepr
obei
shi
t
byt
hev
ol
t
ageandv
i
br
at
es.Thev
i
br
at
i
oncr
eat
esanul
t
r
asoni
cpul
sewhi
chent
er
s
t
het
estmat
er
i
al
.Thepul
set
r
av
el
st
hr
ought
hemat
er
i
alunt
i
li
tst
r
i
kesar
ef
l
ect
or
andi
sr
ef
l
ect
edbackt
ot
hepr
obe.I
tr
eent
er
st
hepr
obe,hi
t
st
hecr
y
st
aland
v
i
br
at
esi
t
,causi
ngi
tt
ogener
at
eav
ol
t
age.Thev
ol
t
agecausesacur
r
entwhi
ch
t
r
av
el
sbackt
ot
hef
l
aw det
ect
oral
ongt
hecabl
e.Thesetdi
spl
ay
st
het
i
met
he
pul
sehast
akent
hr
ought
het
estmat
er
i
al
andbackandt
hest
r
engt
hoft
hepul
seas
asi
gnal
ont
heCRTscr
een.
Thi
si
sbasi
cal
l
yhowaUTsetwor
ks.I
tt
r
ansmi
t
sener
gyi
nt
omat
er
i
alv
i
aapr
obe
andmeasur
est
het
i
mei
nmi
cr
osecondst
hatt
hesoundpul
set
akest
or
et
ur
nt
ot
he
pr
obe.Thecont
r
ol
sont
heUTsetar
eal
mostent
i
r
el
yconcer
nedwi
t
hpr
esent
i
nga
di
spl
ayont
heCRTscr
eenf
ort
heoper
at
ort
oi
nt
er
pr
et
.
9.
3.
2 Cat
hoder
ayt
ube
Thecat
hoder
ayt
ubei
sadev
i
cef
ormeasur
i
ngv
er
ysmal
l
per
i
odsoft
i
me.TheCRT
di
spl
ay
sel
ect
r
i
calpul
sesonascr
eeni
nal
i
neart
i
me/
di
st
ancer
el
at
i
onshi
p.Thati
s,
t
hel
ongert
hedi
st
anceont
hescr
eent
i
mebase,
t
hel
ongert
het
i
met
hathasbeen
measur
ed.
Howt
heCRTwor
ks
Af
i
l
amenti
sheat
edi
nav
acuum t
ube.Theheatcausest
hepar
t
i
cl
esoft
he
f
i
l
amentt
ov
i
br
at
eandel
ect
r
onsst
ar
tboi
l
i
ngoutoft
hesur
f
ace,apr
ocessknown
ast
her
mi
oni
cemi
ssi
on.
Aposi
t
i
v
epot
ent
i
alel
ect
r
i
cchar
gei
nposi
t
i
onf
ur
t
herdownt
hev
acuum t
ubeand
t
henegat
i
v
el
ychar
gedel
ect
r
onsf
r
om t
hef
i
l
amentar
eat
t
r
act
edt
owar
dsi
t
.The
el
ect
r
onspasst
hr
oughanegat
i
v
el
ychar
gedf
ocusi
ngr
i
ngwhi
chpushest
hem
t
owar
dst
hecent
r
eoft
het
ube,f
or
ci
ngt
hem i
nt
oaf
i
nest
r
eam.Thi
sst
r
eam of
el
ect
r
onshi
t
saphosphorcov
er
edscr
eenatt
heendoft
het
ube.Theel
ect
r
on
bombar
dmentf
or
cest
hephosphort
ogi
v
eoutl
i
ghtandagr
eendotappear
sont
he
scr
een.
TheXandYpl
at
esabov
e,bel
owandbesi
det
heel
ect
r
onst
r
eam car
r
ypot
ent
i
al
s
t
hatmov
et
heel
ect
r
onst
r
eam f
r
om si
det
osi
deandupanddown,mov
i
ngt
he
gr
eendotont
hescr
een.
The X pl
at
es cont
r
olhor
i
zont
almov
ementand t
he Y pl
at
es cont
r
olv
er
t
i
cal
mov
ement
. Byal
t
er
i
ngt
hepot
ent
i
aloft
heXandYpl
at
es,
t
hedotcanbemov
ed
ont
hescr
een.
9.
3.
3 Th
ePu
l
s
eGe
n
e
r
a
t
o
r
:
Th
ep
u
l
s
eGe
n
e
r
a
t
ori
sa
l
s
ok
n
own a
st
h
ec
l
oc
k ort
i
me
rt
h
i
sc
i
r
c
u
i
t
c
on
t
r
ol
st
h
es
y
n
c
h
r
on
i
z
a
t
i
on oft
h
ef
l
a
w d
e
t
e
c
t
or
. I
t s
e
n
d
s a
n
e
l
e
c
t
r
i
c
a
ls
i
g
n
a
lt
ot
h
et
i
me
b
a
s
eg
e
n
e
r
a
t
or a
n
d t
o t
h
e p
u
l
s
e
t
r
a
n
s
mi
t
t
e
rs
i
mu
l
t
a
n
e
ou
s
l
y
.Th
e
s
ee
l
e
c
t
r
i
c
a
ls
i
g
n
a
lf
r
e
qu
e
n
c
i
e
s a
r
e
k
n
own a
sPRF
/
PRR
(
Pu
l
s
e
Re
pe
t
i
t
i
on
F
r
e
qu
e
n
c
y
/
Pu
l
s
e
Re
p
e
t
i
t
i
on Ra
t
e
)
.I
ti
s u
s
u
a
l
l
yc
on
t
r
ol
l
e
d
a
u
t
oma
t
i
c
a
l
l
yb
yt
h
er
a
n
g
e(
c
oa
r
s
e
)c
on
t
r
ols
e
t
t
i
n
g
,t
h
i
si
nt
u
r
n
u
l
t
i
ma
t
e
l
yc
on
t
r
ol
st
h
ema
x
i
mu
md
e
p
t
hofi
n
s
p
e
c
t
i
ona
n
dt
h
eu
l
t
i
ma
t
e
s
c
a
n
n
i
n
gs
p
e
e
d
.
9.
3.
4Th
eTi
me
b
a
s
eg
e
n
e
r
a
t
o
r
:
Th
et
i
mb
a
s
eg
e
n
e
r
a
t
ori
sa
l
s
ok
n
own a
s s
we
e
p g
e
n
e
r
a
t
or
,u
p
on
r
e
c
e
i
v
i
n
gt
h
ee
l
e
c
t
r
i
c
a
ls
i
g
n
a
lf
r
om t
h
epu
l
s
ege
n
e
r
a
t
ort
h
i
sc
i
r
c
u
i
t
c
on
t
r
ol
st
h
ev
ol
t
a
georc
h
a
r
geont
h
eXpl
a
t
e
sc
a
u
s
i
n
gt
h
ee
l
e
c
t
r
on
b
e
a
mi
nt
h
ec
a
t
h
od
er
a
yt
u
b
et
os
we
e
pa
c
r
os
st
h
es
c
r
e
e
ni
nal
i
n
e
a
r
mot
i
on
.
9.
3.
5Th
ePu
l
s
et
r
a
n
s
mi
t
t
e
r
:
Th
ep
u
l
s
et
r
a
n
s
mi
t
t
e
rorp
u
l
s
e
rc
i
r
c
u
i
t
,t
h
ee
l
e
c
t
r
i
c
a
ls
i
g
n
a
lf
r
om t
h
e
p
u
l
s
eg
e
n
e
r
a
t
ort
r
i
g
g
e
r
st
h
i
sc
i
r
c
u
i
tt
os
e
n
dab
u
r
s
tofe
l
e
c
t
r
i
c
a
l
e
n
e
r
g
y
,
a
b
ou
t1t
o2
Kv
,
t
oa
c
t
i
v
a
t
et
h
ep
r
ob
e
.
9.
3.
6Thepr
obeors
e
ar
c
huni
t
:
I
tc
onv
e
r
t
st
hee
l
e
c
t
r
i
c
a
le
ne
r
gy
,
s
e
ntbyt
hepul
s
et
r
a
ns
mi
t
t
e
r
,
i
nt
opul
s
e
s
oful
t
r
a
s
oundbyme
ans ofapi
e
z
oe
l
e
c
t
r
i
c c
r
y
s
t
a
l(
Tx
)
.The r
e
t
ur
ni
ng
ul
t
r
a
s
oundf
r
om t
het
e
s
tma
t
e
r
i
a
l
i
sc
onv
e
r
t
e
dba
c
ki
nt
oe
l
e
c
t
r
i
c
a
l
e
ne
r
gyby
t
hepr
obe(
Rx
)a
nds
e
ntt
ot
hea
mpl
i
f
i
e
r
.
9.
3.
7Th
eAmpl
i
f
i
e
r
:
Th
er
e
c
e
i
v
e
ra
mpl
i
f
i
e
rc
i
r
c
u
i
ta
c
c
e
pt
sa
n
da
mpl
i
f
i
e
st
h
ei
n
c
omi
n
g
e
l
e
c
t
r
i
c
a
l
pu
l
s
e
s
.Th
ea
mp
l
i
f
i
c
a
t
i
onr
e
qu
i
r
e
di
sa
b
ou
t1
0
,
0
0
0t
o1
0
0
,
0
0
0
t
i
me
sa
n
dt
h
eou
t
p
u
tmu
s
tb
el
i
n
e
a
rwi
t
ht
h
ei
n
p
u
t
.Th
ea
mp
l
i
f
i
e
rmu
s
t
a
l
s
ob
ec
a
p
a
b
l
eofa
c
c
e
p
t
i
n
gar
a
n
g
eofdi
f
f
e
r
e
n
tf
r
e
qu
e
n
c
ys
i
g
n
a
l
st
o
a
c
c
ommoda
t
et
h
er
a
n
g
eofp
r
ob
ef
r
e
qu
e
n
c
i
e
su
s
e
d
.
Br
oa
d ba
n
da
mpl
i
f
i
e
r
s
,ac
c
e
p
ta v
e
r
y wi
d
ea
r
r
a
y off
r
e
qu
e
n
c
i
e
s
p
r
od
u
c
i
n
ga
na
c
c
u
r
a
t
er
e
p
r
e
s
e
n
t
a
t
i
onofs
i
g
n
a
ls
h
a
p
e
.Th
i
se
n
h
a
n
c
e
s
d
e
f
e
c
ti
n
t
e
r
p
r
e
t
a
t
i
on(
t
y
p
e
)b
u
tt
h
es
i
g
n
a
l
t
on
oi
s
er
a
t
i
owi
l
l
b
ep
oor
,
s
o
de
f
e
c
t d
e
t
e
c
t
i
on ma
y b
ea
d
v
e
r
s
e
l
ya
f
f
e
c
t
e
d
,i
.
e
.a r
e
d
u
c
t
i
on i
n
s
e
n
s
i
t
i
v
i
t
y
,
b
e
c
a
u
s
eofh
i
g
hn
oi
s
e(
org
r
a
s
s
)l
e
v
e
l
s
.
Na
r
r
ow ba
n
da
mpl
i
f
i
e
r
s
,o
nt
h
eot
h
e
rh
a
n
d
,s
u
p
p
r
e
s
st
h
ep
a
r
t
soft
h
e
s
i
g
n
a
l
t
h
a
ta
r
e ou
t
s
i
d
et
h
ef
r
e
qu
e
n
c
yba
n
dt
h
a
ti
tope
r
a
t
e
sa
t(
t
h
ep
a
s
s
f
r
e
qu
e
n
c
y
)
.Th
i
sc
r
e
a
t
e
sa c
l
e
a
n
e
rs
i
g
n
a
l(
a
l
t
h
ou
g
h n
ot a t
r
u
e
r
e
p
r
e
s
e
n
t
a
t
i
on of t
h
ei
n
p
u
ts
i
g
n
a
l
)
,wh
i
c
h me
a
n
st
h
a
tt
h
eg
a
i
n
(
a
mp
l
i
f
i
c
a
t
i
on
)c
a
nb
ei
n
c
r
e
a
s
e
d wh
i
c
hi
nt
u
r
ne
n
h
a
n
c
e
sd
e
f
e
c
t
d
e
t
e
c
t
a
b
i
l
i
t
y(
s
e
n
s
i
t
i
v
i
t
y
)
.Th
edi
s
a
dv
a
n
t
a
geoft
h
i
si
st
h
a
tt
h
ea
l
t
e
r
e
d
s
h
a
p
eoft
h
es
i
gn
a
l
me
a
n
st
h
a
td
e
f
e
c
ti
n
t
e
r
p
r
e
t
a
t
i
oni
smor
ed
i
f
f
i
c
u
l
t
.
9.
3.
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t
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n
u
a
t
o
ro
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t c
on
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s r
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om t
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,
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ONPROBEUSES
10.
1.
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l
i
br
a
t
i
on
:
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l
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)
.
10.
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oneme
as
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nt(
s
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ec
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s
t
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pr
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)
:
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ft
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e
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t
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et
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eBWEs
.
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ockandobt
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om t
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per
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10.
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Fora45or60°pr
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ockappr
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1.
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.
10.
1.
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e
a
rpr
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t
pu
t
:
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et
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i
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om t
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or
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10.
2BLOCKNo.
2,
A4,
V2,
DI
N54/
122ORKI
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COMPRESSI
ONPROBEUSES
10.
2.
1Ca
l
i
br
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t
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:
Thi
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e
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ts
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om t
hi
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.
10.
2.
2SHEARPROBEUSES:
Pr
obec
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l
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br
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t
i
on
:
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t
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r
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mi
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st
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mm r
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ra
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adi
us
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hes
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;
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e
t
c
.
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2.
3I
n
de
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tpoi
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t
:
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i
n
gt
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e25mm ort
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.
10.
2.
4Pr
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c
k
:
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x
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et
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c
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r
om t
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kt
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ef
r
om t
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pos
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t
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.
10.
3I
NSTI
TUTEOFWELDI
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.
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)/
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l
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a
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i
a
.
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r
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9
,
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om t
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11.
1.
4MUL
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11.
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11.
2.
1 DEFECTDETECTI
ON
Wh
e
nu
s
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n
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r
ob
et
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r
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ord
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t
swemu
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11.
3SENSI
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TY
Ther
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et
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l
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11.
3.
2Gr
a
s
s
Th
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r
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r
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om t
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s
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b
t
r
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gd
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oorf
r
om t
h
eg
a
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n
.
11.
3.
3Re
f
e
r
e
nc
er
e
f
l
e
c
t
or
s
Ac
ommonme
t
hodofs
e
t
t
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ngs
e
ns
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t
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t
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tama
x
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i
gna
lf
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om
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r
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l
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t
or
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r
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ore
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r
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11.
3.
4
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udecur
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lr
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l
ect
or
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nt
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achmentscal
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whet
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oduced
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or
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11.
4SCANNI
NGPATTERNS0˚PROBE
Whe
ns
c
a
nni
ngf
orde
f
e
c
t
st
hes
c
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ook
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r 100mm t
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5 SI
ZI
NGMETHODS0˚PROBE
Ther
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ourmai
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i
z
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s
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t
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1dBdr
opt
e
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h
n
i
qu
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Us
e
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os
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el
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et
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a
l
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f
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c
e
.
11.
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2Equ
a
l
i
s
a
t
i
ont
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c
h
n
i
qu
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Thee
qua
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udet
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Att
hi
spos
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ont
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ger
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l
a
w mus
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o be a
l
ongt
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el
i
neoft
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e
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f
f
e
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t
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d.
11.
5.
3Ma
x
i
mu
ma
mpl
i
t
u
de(
ma
x
.
a
mp)t
e
c
h
n
i
qu
e
:
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si
sus
e
dt
os
i
z
ea
r
e
a
sofs
ma
l
lde
f
e
c
t
s
,
s
uc
ha
si
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l
us
i
ons
,
ort
os
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z
e
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t
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a
c
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t
e
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t
s
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uc
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sc
r
a
c
k
s
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e
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hni
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v
e
smov
i
ng
t
he pr
obe of
ft
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e
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ta
r
e
aunt
i
lt
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i
gna
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s
a
ppe
a
r
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ns
l
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es
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eoneoft
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ma
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rme
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ta
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e
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st
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z
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tora
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11.
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4 Di
s
t
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z
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ng(
D.
G.
S.
)
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s
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r
om f
l
a
tb
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om h
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om d
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h
ee
qu
i
v
a
l
e
n
ts
i
z
e
oft
h
er
e
f
l
e
c
t
or
.
12.
0Ul
t
r
asoni
cEqui
pmentChecks
12.
1Li
near
i
t
yoft
i
me
baseGener
al
Thi
scheckmaybecar
r
i
edoutusi
ngast
andar
dcal
i
br
at
i
onbl
ocke.
g.A2anda
compr
essi
onalwav
epr
obe.Thel
i
near
i
t
yshoul
dbecheckedov
erar
angeatl
east
equal
t
ot
hatwhi
chi
st
obeusedi
nsubsequentt
est
i
ng.
Met
hod
a)Pl
acet
hepr
obeont
he25mm t
hi
cknessoft
heA2bl
ockandadj
ustt
he
cont
r
ol
st
odi
spl
ayt
enBWEs.
b)Adj
ustt
hecont
r
ol
ssot
hatt
hef
i
r
standl
astBWEscoi
nci
dewi
t
ht
hescal
e
mar
ksat1and10.
c)I
ncr
easet
hegai
nt
obr
i
ngsuccessi
v
ebackwal
lechoest
o80% FSH.The
l
eadi
ngedgeofeachechoshoul
dl
i
neupwi
t
ht
heappr
opr
i
at
egr
at
i
cul
el
i
ne.
d)Recor
d any dev
i
at
i
ons atappr
oxi
mat
el
y hal
fscr
een hei
ght
.Dev
i
at
i
ons
shoul
dbeexpr
essedasaper
cent
ageoft
her
angebet
weent
hef
i
r
standl
ast
echoesdi
spl
ay
ed(
i
.
e.225mm)
.
Tol
er
ance
Unl
essot
her
wi
sespeci
f
i
edbyt
het
est
i
ngst
andar
d,
at
ol
er
anceof±2%i
s
consi
der
edaccept
abl
e.
Fr
equencyofchecki
ng
Thi
scheckshal
l
becar
r
i
edoutatl
eastonceperweek.
12.
2Li
near
i
t
yofequi
pment
gai
nGener
al
Thi
si
sacheckonbot
ht
hel
i
near
i
t
yoft
heampl
i
f
i
erwi
t
hi
nt
hesetand t
he
cal
i
br
at
edgai
ncont
r
ol
.I
tcanbecar
r
i
edoutonanycal
i
br
at
i
onbl
ockcont
ai
ni
nga
si
dedr
i
l
l
ed hol
e and shoul
d be t
he pr
obe t
o be used i
n subsequentt
est
i
ng.
Rej
ect
/
suppr
essi
oncont
r
ol
sshal
l
beswi
t
chedof
f
.
Met
hod
•Posi
t
i
ont
hepr
obeonacal
i
br
at
i
onbl
ockt
oobt
ai
nar
ef
l
ect
edsi
gnal
f
r
om asmal
l
r
ef
l
ect
oreg1.
5mm hol
ei
nt
heA2bl
ock.
•Adj
ustt
hegai
nt
osett
hi
ssi
gnal
t
o80%FSHandnot
et
hegai
nset
t
i
ng(
dB)
.
•-I
ncr
easet
hegai
nby2dBandr
ecor
dt
heampl
i
t
udeoft
hesi
gnal
.
-Remov
et
he2dBandr
et
ur
nt
hesi
gnal
t
o80%FSH.
-Reducet
hegai
nby6dBandr
ecor
dsi
gnal
ampl
i
t
ude.
-Reducet
hegai
nbyaf
ur
t
her12dB(
18i
nt
ot
al
)andr
ecor
dsi
gnal
ampl
i
t
ude.
-Reducet
hegai
nbyaf
ur
t
her6dB(
24i
nt
ot
al
)andr
ecor
dsi
gnal
ampl
i
t
ude.
Tol
er
ance
Gai
n,
dB
Expect
ed
ampl
i
t
ude,
%
+
100%
Notl
esst
han
0
80%
N/
A
6
10%
812%
18
40%
3545%
24
5%
Vi
si
bl
eabov
ebase
l
i
ne
Fr
equencyofchecki
ng
Recor
ded
ampl
i
t
ud
e
Thecheckshal
l
becar
r
i
edoutatl
eastonceperweek.
Accept
abl
el
i
mi
t
s
12.
3Pr
obei
ndexandbeam
al
i
gnmentI
ndexpoi
nt
Gener
al
Thecheckf
orpr
obei
ndexappl
i
esonl
yt
oshearwav
epr
ov
es,
andi
st
hef
i
r
stpr
obe
char
act
er
i
st
i
ct
obecheckedonashearwav
epr
obe.Thepr
obei
ndexmaybe
checkedont
hest
andar
dA2cal
i
br
at
i
onbl
ock.
Met
hod
a)Posi
t
i
ont
hepr
obeont
heappr
opr
i
at
esi
deoft
hebl
ockt
oobt
ai
nar
ef
l
ect
i
on
f
r
om t
hequadr
ant
.
b)Mov
et
hepr
obebackwar
dsandf
or
war
dst
omaxi
mi
set
heampl
i
t
udeoft
he
r
ef
l
ect
edsi
gnal
.
c)Whent
hesi
gnal
i
satmaxi
mum,
t
hepr
obei
ndexwi
l
l
cor
r
espondt
ot
he
engr
av
edl
i
neont
hebl
ock.Mar
kt
hi
sposi
t
i
onont
hesi
deoft
hepr
obe.
Tol
er
ance
Tol
er
ancewi
l
l
dependonappl
i
cat
i
onbutf
orpl
ot
t
i
ngofdef
ect
si
ti
sr
ecommended
t
hatpr
obei
ndexi
saccur
at
et
owi
t
hi
n±1mm.
Fr
equencyofchecki
ng
Whenapr
obei
si
ncont
i
nuoususe,i
ti
sr
ecommendedt
hatt
hecheckbecar
r
i
ed
outev
er
yf
ewhour
s;
ot
her
wi
se,
adai
l
ychecki
sr
ecommended.
Beam al
i
gnment(
squi
nt
)
Wi
t
ht
hepr
obest
i
l
l
i
nposi
t
i
on,
acheckonbeam al
i
gnmentcanbeper
f
or
med.I
ft
he
pr
obebeam i
scor
r
ect
l
yal
i
gned,t
heedgeoft
hepr
obewi
l
lbepar
al
l
elt
ot
heedge
oft
hebl
ock.I
ft
hi
si
snott
hecase,measur
et
hesqui
ntangl
ebet
weent
het
wo
edges.Tol
er
ancedependsupont
heaccur
acyofdef
ectpl
ot
t
i
ngr
equi
r
ed.The
checkshoul
dbecar
r
i
edoutonceperweek.
12.
4Beam
angl
eGener
al
Beam angl
ecanbecheckedonsev
er
alcal
i
br
at
i
onbl
ocksegA2orA5.Thebeam
angl
echeckshal
lpr
ef
er
abl
ebemadeonapr
obei
nconj
unct
i
onwi
t
ht
hef
l
aw
det
ect
ort
obeusedi
nsubsequentt
est
i
ng.
Met
hod
a)Pl
acet
hepr
obei
nsuchaposi
t
i
onast
or
ecei
v
ear
ef
l
ect
edsi
gnalf
r
om t
he
sel
ect
edt
r
ansv
er
sehol
ei
nt
hecal
i
br
at
i
onbl
ock(
eg19mm deephol
ei
nt
he
A5bl
ock)
.
b)Max
i
mi
set
hesi
gnalf
r
om t
hehol
eandmar
kt
hei
ndexpoi
ntoft
hepr
obeon
t
hebl
ock.
c)Measur
et
hedi
st
ancef
r
om t
hemar
kedpoi
ntont
hebl
ockt
ot
heedgeoft
he
bl
ock.Knowi
ngt
heposi
t
i
onoft
hedr
i
l
l
edhol
ewi
l
lal
l
owt
hebeam angl
et
o
becal
cul
at
ed(
seebel
ow)
.
Not
eI
fonl
yar
api
dchecki
sr
equi
r
ed,maxi
mi
set
hesi
gnalf
r
om t
he50mm hol
ei
n
t
heA2bl
ock.Theangl
ecant
henbeassessedbyv
i
suali
nt
er
pol
at
i
onbet
weent
he
r
ef
er
encemar
ki
ngsont
hebl
ock.
Tol
er
ance
Theaccur
acybyt
hedescr
i
bedmet
hodi
s±1.
5°
.
Theaccur
acyi
nt
hi
scasecanonl
ybeassumedt
obe±3°
.
Fr
equencyofchecki
ng.
Whenapr
obei
si
ncont
i
nuoususe,i
ti
sr
ecommendedt
hatt
hecheckbecar
r
i
ed
outatl
eastev
er
yf
ewhour
s;
ot
her
wi
se,
adai
l
ychecki
sr
ecommended.
12.
5Sensi
t
i
v
i
t
yandsi
gnal
t
onoi
se
r
at
i
oGener
al
Themai
nobj
ect
i
v
eoft
hi
schecki
st
opr
ov
i
det
heoper
at
orwi
t
hasi
mpl
emet
hod
whi
ch wi
l
li
dent
i
f
ydet
er
i
or
at
i
oni
nsensi
t
i
v
i
t
yoft
hepr
obeandf
l
aw det
ect
ori
n
combi
nat
i
on.
Met
hod
a)Pl
acet
hepr
obeon t
heA2 cal
i
br
at
i
on bl
ockand adj
usti
t
sposi
t
i
on t
o
maxi
mi
set
hesi
gnal
f
r
om t
he1.
5mm di
amet
erhol
e.
b)Adj
ustt
hegai
ncont
r
ol
t
osett
hi
ssi
gnal
t
o20%FSHandnot
et
hedBset
t
i
ng.
c)I
ncr
easet
hegai
nunt
i
lt
heov
er
al
lsy
st
em noi
se(
el
ect
r
oni
cnoi
seandgr
ai
n
st
r
uct
ur
egr
ass)att
hesamer
angeast
het
ar
gethol
er
eached20%FSHand
not
et
henewdBset
t
i
ng.
d)Thef
i
r
stgai
nmeasur
ementnot
edpr
ov
i
desacheckont
hesensi
t
i
v
i
t
yoft
he
pr
obeandf
l
aw det
ect
or
,andt
hedi
f
f
er
encebet
weent
hef
i
r
standsecond
measur
ement
s(
dB)gi
v
est
heS/
Nr
at
i
o.
Not
e1 A demonst
r
at
i
on oft
hesensi
t
i
v
i
t
yofpr
obeand f
l
aw det
ect
oron a
cal
i
br
at
i
on bl
ockdoesnotguar
ant
eet
hatt
hesamesi
zeofr
ef
l
ect
orcoul
dbe
det
ect
edi
nt
hewor
kpi
ece.
Not
e2I
fi
ti
sdesi
r
edt
ocheckt
hesensi
t
i
v
i
t
yasaf
unct
i
onofr
ange,
t
heuseoft
he
st
andar
dA5bl
ocki
sr
ecommendedf
orl
ongerr
anges.
Tol
er
ance
Tol
er
ancewi
l
ldependonappl
i
cat
i
on.Anydet
er
i
or
at
i
oni
nt
hesensi
t
i
v
i
t
yv
al
uewi
l
l
i
ndi
cat
eapr
obl
em wi
t
ht
hepr
obeorf
l
awdet
ect
or
.Al
owS/
Nr
at
i
owoul
dbet
y
pi
cal
ofacoar
segr
ai
nedmat
er
i
al
.
Fr
equencyofchecki
ng
Unl
essot
her
wi
seagr
eed,
t
hecheckshal
l
becar
r
i
edoutonceperpr
obeperday
.
12.
6Pul
se
dur
at
i
onGener
al
Thi
scheckont
hepr
obeandf
l
awdet
ect
ori
ncombi
nat
i
on,
measur
est
heef
f
ecton
t
hedi
spl
ay
edsi
gnalofpr
obedampi
ng,ampl
i
f
i
erbandwi
dt
h,bui
l
t
i
nsuppr
essi
on
andsmoot
hi
ngci
r
cui
t
s.Thest
andar
dA2cal
i
br
at
i
onbl
ockmaybeusedf
ort
hi
s
check.
Met
hod
a)Cal
i
br
at
et
het
i
mebasei
nmi
l
l
i
met
r
est
oar
anget
hati
st
obeusedi
n
subsequentt
est
i
ng.
b)Max
i
mi
set
hesi
gnal
f
r
om t
he1.
5mm si
dedr
i
l
l
edhol
ef
orshearwav
epr
obes
oraBWEf
orcompr
essi
onwav
epr
obesandseti
t
speakt
o100%scr
een
hei
ght
.
c)Measur
et
hewi
dt
hoft
hesi
gnal
i
nmi
l
l
i
met
r
esatt
he10%scr
eenhei
ght
posi
t
i
on.
d)I
fdesi
r
ed,
t
hemeasur
ementi
nmi
l
l
i
met
r
escanbeconv
er
t
edi
nt
o
mi
cr
osecondsbydi
v
i
di
ngi
tbyt
her
el
ev
antsoundv
el
oci
t
y
.
Tol
er
ance
Tol
er
ancewi
l
ldependuponappl
i
cat
i
on.A l
ongpul
sedur
at
i
onwi
l
ll
i
mi
tr
ange
r
esol
ut
i
onandi
ndi
cat
et
heneedf
orar
esol
ut
i
oncheck(
Ar
esol
ut
i
onchecki
s
descr
i
bed i
n Cl
auseNo.
7)
,and ashor
tpul
sedur
at
i
on mayi
ndi
cat
et
hef
l
aw
det
ect
orhasbui
l
t
i
n suppr
essi
on t
hatcoul
d pr
ev
entt
heobser
v
at
i
onofsmal
l
si
gnal
s.
Fr
equencyonchecki
ng
Unl
essot
her
wi
seagr
eed,
t
hecheckshoul
dbecar
r
i
edoutdai
l
y
.
12.
7Resol
v
i
ngpower
(
r
esol
ut
i
on)Gener
al
Thi
scheckdet
er
mi
nest
heabi
l
i
t
yofanul
t
r
asoni
cf
l
aw det
ect
i
onsy
st
em t
ogi
v
e
separ
at
ei
ndi
cat
i
onofdi
scont
i
nui
t
i
essi
t
uat
edcl
oset
oget
herandsi
mul
t
aneousl
y
wi
t
hi
nt
hesoundbeam.
Met
hod
a)Cal
i
br
at
et
het
i
mebaset
oar
angeof0100mm f
orei
t
hert
hecompr
essi
onor
t
heshearwav
epr
obe.
b)Pl
acet
hepr
obesot
hatt
heaxi
soft
hebeam i
mpi
ngesupont
he2mm st
epi
n
t
he A7 cal
i
br
at
i
on bl
ock f
orshearwav
e pr
obes,ort
he 3mm st
ep f
or
compr
essi
onwav
epr
obes.
c)Adj
ustt
heposi
t
i
onoft
hepr
obesot
hatt
heechoesf
r
om t
het
wot
ar
get
sar
e
oft
hesamehei
ghtandappr
oxi
mat
el
yhal
ff
ul
l
gr
at
i
cul
ehei
ght
.
d)Thest
epsar
esai
dt
ober
esol
v
edwhent
hei
rechoesar
ecl
ear
l
ysepar
at
edat
hal
fmaxi
mum echohei
ghtorl
ower
.
Not
eThe3mm st
epbet
weent
he9and3mm dr
i
l
l
edhol
esi
nt
heA6cal
i
br
at
i
on
bl
ockmayal
sobeusedwhenchecki
ngcompr
essi
onpr
obes.
Fr
equencyofchecki
ng
The checkshal
lbe car
r
i
ed outmont
hl
y
,orwhen t
oo l
ong a pul
se dur
at
i
on i
s
suspect
ed.
13.
0 Sensi
t
i
v
i
t
ySet
t
i
ng
Set
t
i
ngasensi
t
i
v
i
t
yl
ev
eli
sessent
i
alt
opr
ov
i
der
epr
oduci
bl
er
esul
t
sf
r
om t
hesame
i
nspect
i
on car
r
i
ed out by di
f
f
er
ent oper
at
or
s usi
ng di
f
f
er
ent pr
obe set
combi
nat
i
onsandmay
bewor
ki
ngi
ndi
f
f
er
entl
ocat
i
ons.Theymustal
lseet
he
samef
l
aw gi
v
i
ngt
hesamesi
gnalhei
ghtandt
her
ef
or
ehav
et
hesamedat
aon
whi
cht
obaset
hei
raccept
/
r
ej
ectdeci
si
ons.Ther
ear
esev
er
alsy
st
emsf
orset
t
i
ng
sensi
t
i
v
i
t
y
.Wehav
eal
r
eadymetoneoft
hem,
f
i
r
stbackwal
lecho(
BWE)t
oFSHf
or
l
ami
nat
i
onchecks.Howev
er
,whenchecki
ngpl
at
eadj
acentt
oawel
d,t
hesecond
BWEshoul
dbet
oFSH.Whenset
t
i
ngsensi
t
i
v
i
t
ywemustbesur
et
hatasi
gnalf
r
om
adef
ectwi
l
lbev
i
si
bl
eont
heCRTscr
eenandt
hatwewi
l
lbeabl
et
odi
st
i
ngui
sht
he
def
ectsi
gnalf
r
om backgr
oundnoi
seorgr
ass.Al
lUTset
sdi
f
f
ersl
i
ght
l
y
,sowe
cannotsay
,‘
Sett
hesensi
t
i
v
i
t
yt
oxdB’
,asdi
f
f
er
entpr
obesandequi
pmentwi
l
lgi
v
e
ent
i
r
el
ydi
f
f
er
entsi
gnal
sf
r
om t
hesamer
ef
l
ect
or
.I
ti
st
oat
t
ai
nsomeuni
f
or
mi
t
y
t
hatt
hedi
f
f
er
entmet
hodshav
eev
ol
v
ed.Di
f
f
er
entmet
hodsar
eusedi
ndi
f
f
er
ent
pl
aces. TheI
OW bl
ocki
susedandi
ti
st
her
ecommendedmet
hodf
orPCN
exami
nat
i
ons.OnNor
t
hSeacont
r
act
st
hedi
st
anceampl
i
t
udecor
r
ect
i
oncur
v
e
(
DAC)met
hodorASMEcur
v
esi
sused.TheDACmet
hodi
sr
ecommendedi
nEN
1714,andi
nGer
manyt
hedi
st
ancegai
nsi
ze(
DGS)sy
st
em i
susual
l
yappl
i
ed,
especi
al
l
ywhenev
al
uat
i
ngsmal
l
r
ef
l
ect
or
s.
Thepur
poseofsensi
t
i
v
i
t
yset
t
i
ngi
st
of
i
ndagai
nl
ev
el
suf
f
i
ci
entt
of
i
ndaf
l
awand
dependsont
he:
a)Pr
obeused,
i
npar
t
i
cul
ari
t
sf
r
equency
b)Fl
awdet
ect
or
c)Pr
oper
t
i
esoft
het
estmat
er
i
al
d)Rat
i
oofnoi
set
oBWEorf
l
awecho
13.
1 TheI
nst
i
t
ut
eofWel
di
ng(
I
OW)bl
ock
Wemett
heI
nst
i
t
ut
eofWel
di
ngbl
ockwhenst
udy
i
ngbeam pr
of
i
l
es.Thebl
ock
cont
ai
ns1.
5mm si
dedr
i
l
l
edhol
esatdi
f
f
er
entdept
hsandal
l
owst
hehol
est
obe
det
ect
ed f
r
om di
f
f
er
entangl
es wi
t
h angl
e pr
obes.To use i
ti
s si
mpl
e and
st
r
ai
ght
f
or
war
d.
Fi
ndahol
eont
hebl
ockt
hatappr
oxi
mat
el
ycoi
nci
deswi
t
ht
het
hi
cknessoft
he
mat
er
i
aly
ouar
et
est
i
ng.Doubl
et
het
hi
cknessi
fy
ouar
eexami
ni
ngatf
ul
lski
p,i
.
e.
bounci
ngy
oursoundbeam of
ft
hebackwal
l
.
Obt
ai
nasi
gnal
f
r
om t
hehol
eandt
ur
nt
hegai
ncont
r
ol
unt
i
l
t
hesi
gnal
i
satFSH.
Wor
koutt
r
ansf
ercor
r
ect
i
on.Youhav
enowsetsensi
t
i
v
i
t
yandcanbeassur
edt
hat
f
l
awshav
i
ngt
heequi
v
al
entr
ef
l
ect
i
v
i
t
yof1.
5mm si
dedr
i
l
l
edhol
eswi
l
lappearon
t
hescr
een.
Thi
smet
hodhassev
er
aladv
ant
ages
•Si
mpl
et
ouse
•Pr
ov
i
desauni
f
or
m sy
st
em ofr
ef
er
ence
•Af
ai
r
l
yl
ar
geandv
i
si
bl
eechoi
sassur
edf
r
om smal
l
f
l
aws
•Si
dedr
i
l
l
edhol
er
ef
l
ect
or
sar
ei
ndependentofangl
e
Butsomedi
sadv
ant
ages
•Bl
ocki
sheav
yandexpensi
v
e
•Onl
yr
ef
er
st
o1.
5mm si
dedr
i
l
l
edhol
es
•Notar
el
i
abl
emet
hodf
orsi
zi
ngdef
ect
s
•Sensi
t
i
v
i
t
ywi
l
l
behi
gherf
orr
angesshor
t
ert
hant
heSDHused
13.
1.
1Di
st
anceampl
i
t
udecor
r
ect
i
on(
DAC)cur
v
es
EN 1714andal
lUSspeci
f
i
cat
i
onsr
ecommendt
hi
smet
hod.Aspeci
alr
ef
er
ence
bl
ockoft
hesamemat
er
i
alast
het
estobj
ecti
susual
l
ynecessar
y
,t
hought
he
cur
v
escanbeconst
r
uct
edf
r
om anI
OW bl
ock.
Thet
y
peofbl
ockr
ecommendedbyEN1714andanASMEbl
ocki
sshownbel
ow
Thepr
ocedur
edescr
i
bedi
nEN1714f
orconst
r
uct
i
ngaDACcur
v
ei
sasf
ol
l
ows:
•Cal
i
br
at
et
het
i
mebasef
ort
hemaxi
mum soundpat
hl
engt
ht
obeused.
•Adj
ustt
hegai
nsot
hatt
heampl
i
t
udef
r
om t
heser
i
esofr
ef
l
ect
or
sf
al
l
sbet
ween
20and80%FSH
•Wi
t
houtal
t
er
i
ngt
hegai
nset
t
i
ng,
maxi
mi
set
heampl
i
t
udeofeachr
ef
l
ect
ori
nt
ur
n
andmar
kt
het
i
poft
hesi
gnal
,
ei
t
heront
hescr
eenoronat
r
anspar
entov
er
l
ay
.
•Recor
dt
hegai
nset
t
i
ngusedf
orpl
ot
t
i
ngt
heDACcur
v
eandr
ef
er
encet
hi
st
o
someot
herr
ef
l
ect
orsuchast
her
adi
usi
naVcal
i
br
at
i
onbl
ock.Thi
sl
at
eract
i
on
enabl
esgai
nt
ober
esetwi
t
houtt
her
ef
er
encebl
ock.
Not
e:Shoul
dt
hedi
f
f
er
encei
nhei
ghtbet
weent
hel
ar
gestandt
hesmal
l
estechoes
exceedt
her
angeof20t
o80%FSH t
hel
i
neshal
lbespl
i
tandsepar
at
ecur
v
es
pl
ot
t
edatdi
f
f
er
entgai
nset
t
i
ngs.Thedi
f
f
er
encei
ngai
nbet
weent
het
wocur
v
es
shal
lbenot
ed.Exami
net
het
estmat
er
i
alasi
nst
r
uct
ed i
nt
hespeci
f
i
cat
i
ons,
compar
i
ngt
hesi
gnal
sf
r
om di
scont
i
nui
t
i
est
ot
hecur
v
esony
ourscr
een.Any
si
gnalabov
et
hecur
v
eshowsar
ef
l
ect
orl
ar
gert
hant
her
ef
er
encehol
e.Acceptor
r
ej
ectdi
scont
i
nui
t
i
esasi
nst
r
uct
edi
nt
hespeci
f
i
cat
i
ony
ouar
ewor
ki
ngt
o.
Adv
ant
ages
•Aqui
ckwayofaccept
i
ngorr
ej
ect
i
ngdi
scont
i
nui
t
i
eswi
t
houtt
oomucht
i
me
consumedi
nsi
zi
ngr
ef
l
ect
or
s.
•Somei
deacanbegai
nedoft
hedi
scont
i
nui
t
i
essi
zei
nr
el
at
i
ont
or
ef
er
encehol
es.
•Uni
f
or
mi
t
ypr
ov
i
dedbyal
l
t
echni
ci
ansconst
r
uct
i
ngt
hei
rcur
v
esf
r
om t
hesame
t
estbl
ock.
Di
sadv
ant
ages
•Cur
v
esmustbeconst
r
uct
edf
oreachpr
obei
nconj
unct
i
onwi
t
heachset
.
•Tr
ansf
ercor
r
ect
i
onmustbewor
kedout
.
13.
2 Fl
at
bot
t
omedhol
es(
FBH)
Bl
ocksar
edr
i
l
l
edwi
t
hf
l
at
bot
t
omedhol
est
opr
eci
sedi
amet
er
sandsetdi
st
ances
f
r
om t
het
opoft
hebl
ock.Thesedi
amet
er
sanddi
st
ancesar
est
ampedont
hesi
de
oft
hebl
ock.
Whenset
t
i
ngsensi
t
i
v
i
t
i
est
hespeci
f
i
cat
i
onort
echni
quewi
l
l
speci
f
yt
hebl
ockt
obe
usedandt
heampl
i
t
udeofsi
gnalt
obeobt
ai
nedf
r
om t
heFBH.Bl
ocksar
ecutf
or
usewi
t
h0°pr
obesorangl
epr
obesi
ndi
f
f
er
entmat
er
i
al
sandt
hi
smet
hodi
smost
l
y
usedi
naer
ospace.
Adv
ant
ages
•Easyt
ouse
•Uni
f
or
mi
t
yassur
edwhendi
f
f
er
entt
echni
ci
ansuset
hesamebl
ocks
•Bl
ockscanbemadef
r
om di
f
f
er
entmat
er
i
al
s
Di
sadv
ant
ages
•Fai
r
l
yr
i
gi
dsy
st
em f
orspeci
f
i
cappl
i
cat
i
ons
•Lar
genumberofbl
ocksneededf
ordi
f
f
er
entset
t
i
ngs
•Tr
ansf
ercor
r
ect
i
onusual
l
yneeded
•Bl
ocksf
orangl
epr
obesar
er
ar
el
ycutexact
l
ynor
mal
t
ot
hebeam.Youmayhear
t
hesebl
ockscal
l
edHI
TTorALCOAbl
ocks,
af
t
ert
heor
i
gi
nat
or
s.
Usi
ngnoi
se
Wor
koutt
hemaxi
mum r
angeatwhi
chy
ouwi
l
lbeexami
ni
ngt
estmat
er
i
al
.Pl
ace
t
he pr
obeont
hemat
er
i
alwi
t
hcoupl
antappl
i
ed.Tur
nupt
hegai
nunt
i
ly
ouhav
e
2mm gr
ass on t
he scr
een att
he maxi
mum r
ange.You wi
l
lnow hav
et
he
assur
anceofknowi
ngt
hat anydi
scont
i
nui
t
yl
ar
gert
hant
hegr
ai
nsi
zewi
l
lshow
upont
hescr
een.
Adv
ant
ages
•Qui
ckandeasy
•Nor
ef
er
encebl
ocki
sneeded
•Anydef
ectl
ar
gert
hant
hemat
er
i
al
gr
ai
nswi
l
l
showup
•Not
r
ansf
ercor
r
ect
i
onneeded
Di
sadv
ant
ages
•Noaccur
at
esi
zi
ngoft
hedef
ect
•Di
scont
i
nui
t
i
esneart
hesur
f
aceoft
het
estmat
er
i
al
maybehi
ddeni
nt
hegr
ass
Tr
ansf
ercor
r
ect
i
on
Ref
er
ence bl
ocksusual
l
yhav
e smoot
h machi
ned sur
f
aceswhi
l
et
estobj
ect
s
f
r
equent
l
y hav
er
ougher
,mor
eunev
ensur
f
aces.Al
sot
heat
t
enuat
i
onofsoundi
n
t
he r
ef
er
ence bl
ock mi
ghtbe di
f
f
er
entt
ot
hati
nt
he t
estmat
er
i
al
.Usual
l
y
at
t
enuat
i
oni
nt
her
ef
er
encebl
ocki
sl
esst
hant
het
estmat
er
i
albutnotal
way
s.
Thi
smeanst
hatal
l
owancemustbemadef
ort
hedi
f
f
er
encesi
nsoundener
gy
t
r
ansf
erbet
weenpr
obeandt
estmat
er
i
alandpr
obeandr
ef
er
encebl
ock.Mor
e
ener
gycan be passed i
nt
oar
ef
er
ence bl
ock t
han i
nt
oar
oughersur
f
aced
component
.Hencet
hear
t
i
f
i
ci
aldef
ect
si
nar
ef
er
encebl
ockmaygi
v
ehi
gher
ampl
i
t
udesi
gnal
s(
any
t
hi
ngupt
o6dBorev
enmor
e)t
hansi
gnal
sf
r
om si
mi
l
ar
l
y
si
zeddi
scont
i
nui
t
i
esi
nt
het
estmat
er
i
al
s.Al
l
owanceshav
et
obemadef
ort
hi
sand
cor
r
ect
i
ons made f
ordi
f
f
er
entsur
f
aces.Thi
s al
l
owance i
s named t
r
ansf
er
cor
r
ect
i
onort
r
ansf
erl
oss.
Ther
ear
esev
er
almet
hodsofdet
er
mi
ni
ngt
r
ansf
ercor
r
ect
i
on,somer
equi
r
i
ngt
he
const
r
uct
i
onofsepar
at
eDACcur
v
esandsomer
equi
r
i
ngcal
cul
at
i
onaccor
di
ng t
o
f
or
mul
ae.Weexpl
ai
nt
wosi
mpl
emet
hods.
Compr
essi
onpr
obemet
hod
Pl
acet
hepr
obeont
her
ef
er
encebl
ockandt
ur
nt
heBWEupt
oFSH.Not
et
hegai
n
set
t
i
ngs.Nowpl
acet
hepr
obeont
het
estmat
er
i
alandatasi
mi
l
arr
angebr
i
ngt
he
BWEt
oFSH.Agai
nnot
et
hegai
nset
t
i
ng.Thedi
f
f
er
encebet
weent
hem i
st
he
t
r
ansf
ercor
r
ect
i
on.
Angl
epr
obemet
hod
Asy
oucannotgetaBWEwi
t
hangl
epr
obesf
r
om apl
at
eorpi
pe wal
l
,
y
ouhav
et
o
uset
wopr
obeswi
t
ht
hesameangl
e.Pl
acet
het
wopr
obesopposi
t
eeachot
heron
t
her
ef
er
encebl
ockwi
t
honepr
obet
r
ansmi
t
t
i
ngandt
heot
herr
ecei
v
i
ng,
sot
hatt
he
soundener
gyi
sbouncedof
ft
hebackwal
landcaughtbyt
her
ecei
v
i
ngpr
obe(
pi
t
ch
andcat
ch)
.Maxi
mi
set
hesi
gnalandadj
ustt
hegai
nunt
i
li
ti
satFSH.Pl
acet
het
wo
pr
obesonapi
eceoft
estmat
er
i
aloft
hesamet
hi
cknessast
her
ef
er
encebl
ock
andr
epeatt
hepr
ocess.Not
et
hedi
f
f
er
encebet
weent
het
wogai
nset
t
i
ngs.Thi
si
s
t
het
r
ansf
ercor
r
ect
i
onneeded.Ot
hermet
hodsoft
r
ansf
ercor
r
ect
i
onar
edescr
i
bed
i
nEN1714andi
nl
i
t
er
at
ur
econcer
ni
ngt
hedi
st
ancegai
nsi
ze(
DGS)sy
st
em.
13.
3 Thedi
st
ancegai
nsi
ze(
DGS)met
hod
TheDGSsy
st
em r
el
i
esont
hel
awsofl
ar
geandsmal
lr
ef
l
ect
or
si
nt
hef
arzoneand
wasdev
el
opedt
or
el
at
et
heampl
i
t
udeofasi
gnalt
ov
ar
i
oussi
zesofper
f
ectdi
sc
r
ef
l
ect
or
s,f
l
at
-bot
t
omedhol
es,soi
tdoesnotact
ual
l
ysi
zef
l
awsbutr
el
at
est
hem
t
oanequi
v
al
entr
ef
l
ect
or
.Ther
el
at
i
v
ehei
ght
sofsi
gnal
sf
r
om di
f
f
er
entsi
zesof
f
l
at
bot
t
omedhol
esatdi
f
f
er
entdi
st
anceswer
epl
ot
t
edascur
v
es.Ref
l
ect
orsi
zes
ar
eexpr
essedi
nt
er
msoft
hepr
obedi
amet
eranddi
st
ancesf
r
om t
hepr
obear
e
expr
essedasmul
t
i
pl
esoft
henearzone.
Nowi
fy
ouhav
easi
gnal
f
r
om af
l
awatacer
t
ai
ndept
h,
y
oucancompar
et
hesi
gnal
si
zet
owhatt
hesi
gnalofaBWEshoul
dbeatt
hatdept
handest
i
mat
et
hesi
zeof
f
l
atbot
t
omedhol
et
hatwoul
dgi
v
esuchasi
gnalatt
hatdept
h.Thedef
ectcant
hen
besi
zedaccor
di
ngt
o af
l
atbot
t
omedhol
eequi
v
al
ent
.Theat
t
enuat
i
onf
act
orf
or
t
het
estmat
er
i
al
mustbet
akeni
nt
oconsi
der
at
i
onwhenusi
ngt
heDGSsy
st
em.
Exampl
e:
Youar
eusi
nga5MHz10mm di
amet
ercompr
essi
onpr
obeon100mm
st
eelpl
at
eandy
ouf
i
ndadef
ectat60mm dept
hwhi
chgi
v
esasi
gnal
atFSHwi
t
h
a30dBgai
nset
t
i
ng.Whati
si
t
sf
l
at
bot
t
omedhol
eequi
v
al
ent
?Fi
r
st
,
wor
koutt
he
pr
obenearzone.I
ti
s21mm,
sot
hedef
ecti
satadi
st
anceoft
hr
eenearzones.
NowgetaBWEandf
i
ndwhatt
hedBr
eadi
ngi
s.Sayi
ti
s20dBwhent
heBWEi
s
atFSH.100mm i
sf
i
v
enearzones.Whatwi
l
l
i
tbeat60mm,
t
hr
eenearzones?
Ref
ert
ot
heDGScur
v
es.I
ft
heBWEi
sFSHwi
t
h20dBat100mm,
byt
hel
awof
l
ar
ger
ef
l
ect
or
sandaccor
di
ngt
ot
heBWEl
i
neont
heDGScur
v
esaBWEat60mm
shoul
dr
eachFSHat16dB,
4dBl
esst
hanat100mm.Thesi
gnal
hei
ghtf
r
om t
he
f
l
awi
s30dB,
14dBmor
et
hant
heBWE.Lookdownt
hescal
e14dBat3nearzones
f
r
om t
heBWEandy
ouf
i
ndt
hatt
henear
estl
i
nei
s0.
5oft
hepr
obedi
amet
er
.The
pr
obedi
amet
eri
s10mm sot
henear
estequi
v
al
entf
l
atbot
t
omedhol
et
ot
hef
l
aw
hadadi
amet
erof5mm.
Bysi
mi
l
arwor
ki
ng,
asensi
t
i
v
i
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i
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oraf
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atbot
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ai
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anget
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l
aw
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ect
orgai
nsetaccor
di
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.
Adv
ant
ages
•Youcanchooseagai
nl
ev
el
f
orsi
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ecty
oucanf
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oughequi
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om di
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at
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ef
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at
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ort
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om t
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at
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ai
ghtof
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de.The
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em i
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del
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nGer
many
.
13.
4 Si
gnal
t
onoi
ser
at
i
o
I
thasbeenment
i
onedel
sewher
et
hatf
r
equencyandwav
el
engt
hhav
eamaj
or
i
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l
uenceonf
l
awdet
ect
i
on.I
nf
act
,
howev
er
,
t
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ect
i
onofadef
ecti
s
i
nf
l
uencedbymanyot
herf
act
or
s.Theamountofsoundt
hatr
ef
l
ect
sf
r
om a
def
ecti
s,
f
orexampl
e,
dependentonacoust
i
ci
mpedancemi
smat
chbet
weent
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f
l
awandt
hesur
r
oundi
ngmat
er
i
al
.Agasf
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l
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eddef
ectsuchasal
ackoff
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oni
s
gener
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l
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t
err
ef
l
ect
ort
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l
i
ci
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f
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er
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n
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ci
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randmet
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t
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and
anot
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.
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eoft
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al
sogr
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l
yaf
f
ect
st
hedet
ect
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onofdef
ect
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wi
t
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ai
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uct
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er
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ngdef
ectdet
ect
abi
l
i
t
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.Ameasur
eof
det
ect
abi
l
i
t
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l
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ectoft
hemanyf
act
or
si
nv
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edi
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t
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gnal
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onoi
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at
i
o(
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at
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oi
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eofhowt
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gnal
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r
om t
hedef
ect
compar
est
oot
herbackgr
oundr
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l
ect
i
ons(
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egor
i
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se)
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at
i
oof3
t
o1i
sof
t
enr
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r
edasami
ni
mum.Theabsol
ut
enoi
sel
ev
el
andt
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ut
e
st
r
engt
hofanechof
r
om asmal
l
def
ectdependsonanumberoff
act
or
s:
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obesi
zeandf
ocal
pr
oper
t
i
es.
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obef
r
equency
,
bandwi
dt
handef
f
i
ci
ency
.
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nspect
i
onpat
handdi
st
ance(
wat
erand/
orsol
i
d)
.
13.
5 Not
c
he
s
:
F
ore
v
a
l
u
a
t
i
n
gi
n
c
omp
l
e
t
ep
e
n
e
t
r
a
t
i
on i
n we
l
d
s ord
i
s
c
on
t
i
n
u
i
t
i
e
s
f
or
mi
n
gac
ome
r
,
s
u
c
ha
sas
u
r
f
a
c
ec
r
a
c
korwe
l
du
n
de
r
c
u
t
,
ma
c
h
i
n
e
d
s
u
r
f
a
c
en
ot
c
h
e
sma
ybee
mpl
oy
e
df
ors
e
n
s
i
t
i
v
i
t
yc
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l
i
br
a
t
i
ona
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ds
i
z
e
c
ompa
r
i
s
on
,
s
i
n
c
et
h
e
ymor
en
e
a
r
l
yr
e
pr
e
s
e
n
tt
h
ea
c
t
u
a
l
d
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s
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on
t
i
n
u
i
t
y
.
AVe
es
h
a
p
e
dn
ot
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hi
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e
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r
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f
e
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ore
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l
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a
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of f
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a
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ot
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h
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r
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l f
or
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l
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e
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on
. Th
e
s
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ot
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h
e
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r
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s
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od
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h
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h
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f
orwe
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pe
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14.
0 Fl
awLocat
i
on:
Youcancal
cul
at
et
hel
ocat
i
onofaf
l
awbyusi
ngt
r
i
gonomet
r
i
cf
or
mul
asasshown
bel
ow.Youneedt
oknowt
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eoft
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hest
andof
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edf
r
om
t
hecent
r
eofawel
d.
Dept
h=Cosθxr
ange
St
andof
f=Si
nθ xr
angeAgener
al
r
ul
eoft
humbusedt
ocal
cul
at
et
hedept
hofan
i
ndi
cat
i
onf
r
om t
her
angeont
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eeni
s
45˚pr
obe-r
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sappr
oxi
mat
el
y1.
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h 60˚pr
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sexact
l
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dept
h
70˚pr
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sappr
oxi
mat
el
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h
I
ti
squi
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er
,howev
er
,t
ouseaf
l
aw l
ocat
i
onsl
i
deandabeam pl
otor
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ast
i
cf
i
l
m wi
t
ht
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edr
awnoni
t
.Uset
hesl
i
deas
f
ol
l
ows:
Dr
aw acr
osssect
i
onoft
hewel
dont
het
r
anspar
entout
erenv
el
opeoft
hesl
i
de.
Dr
aw ami
r
r
ori
mageoft
hewel
dcr
osssect
i
oni
mmedi
at
el
yunderi
ti
ft
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gyi
sgoi
ng t
obounceof
ft
hebackwal
l
,i
.
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ngf
ul
lski
p.Uset
hepr
i
nt
ed
dat
um l
i
neont
hepl
ast
i
cenv
el
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r
eoft
hewel
dandmeasur
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lst
andof
f
sf
r
om i
t
.Maxi
mi
set
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r
om adef
ectandmar
kwher
et
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ndexpoi
ntf
al
l
s
ont
hepar
entmet
al
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ei
t
sdi
st
ancef
r
om t
hecent
r
eoft
hewel
d.
Not
et
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ectonasket
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et
hest
andof
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angeoft
hecent
r
eoft
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def
ect
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et
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um l
i
neont
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ast
i
cenv
el
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ot
hest
andof
fdi
st
ance.
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ongt
hecent
r
eoft
hebeam pl
otunt
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l
y
oucomet
ot
her
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scr
een.Makeamar
kont
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el
ope,
t
hi
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epr
esent
st
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r
eoft
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ect
.I
t
showst
hedef
ect
sposi
t
i
oni
nt
hewel
dbody
.
14.
1 THEI
RRADI
ATI
ONFACTOR
Whent
es
t
i
ngt
ubul
armat
er
i
al
sar
oundt
hec
i
r
c
umf
er
enc
ewi
t
hangl
epr
obes
,
i
t
i
spos
s
i
bl
et
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ot
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ur
v
at
ur
e,wal
lt
hi
c
k
nes
sandpr
obeangl
e,t
hatt
he
beam wi
l
lnots
t
r
i
k
et
hei
ns
i
des
ur
f
ac
eoft
hemat
er
i
al
.Wec
anc
al
c
ul
at
et
he
mi
ni
mum pr
obe angl
et
hatwi
l
ls
t
r
i
k
et
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ns
i
des
ur
f
ac
eoft
hemat
er
i
al(
ata
t
angent
)
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si
sk
nownast
hei
r
r
adi
at
i
onf
ac
t
or
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et
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l
lr
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h
t
hebor
ei
sc
al
c
ul
at
edbyt
hef
ol
l
owi
ngf
or
mul
a.
14.
2 F
l
a
wSi
z
i
n
g:
SI
ZI
NGMETHODSANGL
EPROBES
Ther
ear
et
hr
eemai
ns
i
z
i
ngt
ec
hni
quesus
edwi
t
hangl
epr
obes
:
•
6dBdr
op
•
20dBdr
op
• Ma
x
i
mu
ma
mp
l
i
t
u
d
e
14.
2.
16dBDr
opt
e
c
h
n
i
qu
e
Us
e
dt
os
i
z
ede
f
e
c
tdi
me
ns
i
onswhi
c
ha
r
el
ar
ge
rt
ha
nt
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am,s
uc
ha
s
t
hel
e
ngt
hofal
a
c
kofs
i
de
wa
l
l
f
us
i
oni
nawe
l
d.
Thepr
obei
smov
e
dof
ft
he
e
ndoft
he de
f
e
c
tunt
i
lt
hes
i
gna
lampl
i
t
udei
sr
e
duc
e
dby50%(
6dB)
.The
pos
i
t
i
onoft
hec
e
nt
r
eoft
hepr
obei
st
he
n ma
r
k
e
dont
ot
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t
e
r
i
a
l
s
ur
f
a
c
e
.Thepr
obei
snow i
napos
i
t
i
onwhe
r
et
he be
a
mi
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l
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ft
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f
e
c
t
.
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ft
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e
pe
a
t
e
da
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re
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e
c
tt
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nt
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s
t
a
nc
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t
we
e
nt
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r
k
sr
e
pr
e
s
e
nt
si
t
sl
e
ngt
h.
14.
2.
220dBDr
opt
e
c
h
n
i
qu
e
Thi
st
e
c
hni
quei
sus
e
df
orde
f
e
c
t
st
ha
ta
r
el
e
s
st
ha
nt
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dt
hoft
hebe
a
m,
s
uc
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st
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r
os
s
s
e
c
t
i
ona
ls
i
z
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c
kofs
i
de
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lf
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t
r
e
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e
st
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eofa20dBbe
a
m pr
of
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l
e
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ot
t
e
doutf
ort
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nus
e
,
dr
a
wnont
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ot
t
i
ngs
y
s
t
e
m.
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i
gna
l
f
r
om t
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f
e
c
ti
sf
i
r
s
tmax
i
mi
s
e
d
a
ndt
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i
t
i
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e
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tpl
ot
t
e
ddownt
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nbe
a
m ont
hepl
ot
t
e
r
a
si
nf
i
g.1.Thepr
obei
st
he
nmov
e
df
or
wa
r
ds
,of
ft
hede
f
e
c
t
,unt
i
lt
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s
i
gna
l
dr
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t
sor
i
gi
nal
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i
ght
.Ast
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smov
e
df
or
war
d
t
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f
e
c
ti
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nt
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r
a
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ng e
dge oft
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m,
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owenowpl
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r
a
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i
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ot
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r
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e
ef
i
g.
2.Thi
ss
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v
e
apoi
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ot
t
e
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us
ta
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et
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e
v
i
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ota
ndt
hi
sr
e
pr
e
s
e
nt
st
het
op
e
dgeoft
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f
e
c
t
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fwenowmov
et
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ds
,
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s
tt
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i
m,
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et
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i
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i
m,t
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ott
he
s
i
gna
ldownt
hel
e
a
di
nge
dgeoft
hebe
a
m,a
si
nf
i
g.
3,t
hi
ss
houl
dgi
v
eus
t
hebot
t
om e
dgeoft
hede
f
e
c
ta
ndt
hust
heov
e
r
a
l
l
s
i
z
e
.
f
i
g.
1
f
i
g.
2
f
i
g.
3
14.
2.
3 Max
i
mum ampl
i
t
ude(
max
.
amp)t
e
c
hni
que
Thi
si
sus
e
dt
os
i
z
ea
r
e
a
sofs
ma
l
l
de
f
e
c
t
s
,
s
uc
ha
si
nc
l
us
i
onsorpor
os
i
t
y
,
ort
os
i
z
emul
t
i
f
a
c
e
t
e
dde
f
e
c
t
s
,s
uc
ha
sc
r
a
c
k
s
.Thet
e
c
hni
quei
nv
ol
v
e
s
mov
i
ngt
hepr
obeof
ft
hede
f
e
c
ta
r
e
aunt
i
lt
hes
i
gna
l
sdi
s
a
ppe
a
r
,t
he
n
s
l
owl
ybr
i
ngi
ngt
hepr
obebac
k
,
wa
t
c
hi
ngt
hewhol
es
i
gna
l
gr
oup,
t
ot
hef
i
r
s
t
pos
i
t
i
onwhe
r
eoneoft
hes
i
gna
l
smax
i
mi
s
e
s
.Thede
f
e
c
ti
st
he
npl
ot
t
e
d
ft
hi
si
sc
a
r
r
i
e
douti
us
i
ngt
hema
i
nbe
a
m ont
hepl
ot
t
i
ngs
y
s
t
e
m.I
nbot
h
di
r
e
c
t
i
onst
he
nt
hec
r
os
s
s
e
c
t
i
ona
l
e
x
t
r
e
mi
t
i
e
soft
hede
f
e
c
ta
r
epl
ot
t
e
dout
.
e
c
hni
quei
sr
e
pe
a
t
e
dmov
i
ngt
hepr
obe l
a
t
e
r
a
l
l
yt
os
i
z
et
hel
e
ngt
hof
Thet
t
hede
f
e
c
tbymar
k
i
ngt
hepos
i
t
i
onoft
hec
e
nt
r
eoft
hepr
obe
.
Thi
st
e
c
hni
quewi
l
lpi
c
koutt
hel
a
s
ti
ndi
v
i
dua
li
nc
l
us
i
onofagr
ouport
he
l
a
s
tf
a
c
e
tofac
r
a
c
kgi
v
i
ngt
heov
e
r
a
l
ls
i
z
eoft
hede
f
e
c
tora
r
e
a
.I
tc
a
n
a
l
s
o beus
e
dt
opl
ott
hes
ha
peofade
f
e
c
ta
nd f
orc
ondi
t
i
on moni
t
or
i
ng
whe
r
ec
r
i
t
i
c
a
ls
i
z
i
ng i
sr
e
qui
r
e
dbypl
ot
t
i
nge
a
c
hi
ndi
v
i
dua
ls
i
gna
li
nt
he
gr
oupa
si
tma
x
i
mi
s
e
s
.
14.
3 Pul
seecho
Ul
t
r
asoni
ci
nspect
i
onsar
el
ar
gel
yper
f
or
medbyt
hepul
seechot
echni
quei
nwhi
ch
asi
ngl
epr
obei
susedt
obot
ht
r
ansmi
tandr
ecei
v
eul
t
r
asound.I
naddi
t
i
ont
ot
he
f
actt
hataccessi
sr
equi
r
edf
r
om onesur
f
aceonl
y
,
f
ur
t
heradv
ant
agesoft
hi
s
t
echni
quear
et
hati
tgi
v
esani
ndi
cat
i
onoft
het
y
peofdef
ect
,
i
t
ssi
zeandi
t
sexact
l
ocat
i
onwi
t
hi
nt
hei
t
em bei
ngt
est
ed.Themaj
ordi
sadv
ant
agei
st
hatpul
seecho
i
nspect
i
oni
sr
el
i
antupont
hedef
ect
shav
i
ngt
hecor
r
ector
i
ent
at
i
onr
el
at
i
v
et
ot
he
beam i
nor
dert
ogener
at
ear
et
ur
ni
ngsi
gnal
t
ot
hepr
obeandi
snott
her
ef
or
e
consi
der
edf
ai
l
saf
e.I
ft
hesoundpul
sehi
t
st
hef
l
awatanangl
eot
hert
han90˚
muchoft
heener
gywi
l
l
ber
ef
l
ect
edawayandnotr
et
ur
nt
ot
hepr
obewi
t
ht
he
r
esul
tt
hatt
hef
l
awwi
l
l
notshowupont
hescr
een.
14.
4 Thr
ought
r
ansmi
ssi
on
Thr
ought
r
ansmi
ssi
onwasusedi
nt
heear
l
yday
sofUTandi
sst
i
l
lusedi
npl
at
e
andbarpr
oduct
i
on.Apr
obeonesi
deofacomponentt
r
ansmi
t
sanul
t
r
asoni
cpul
se
t
oar
ecept
orpr
obeont
heot
hersi
de.Theabsenceofapul
secomi
ngt
ot
he
r
ecei
v
eri
ndi
cat
esadef
ect
.
NoDef
ect
Def
ect
Theadv
ant
agesar
e
•Lessat
t
enuat
i
onofsoundener
gy
•Nopr
ober
i
ngi
ng
•Nodeadzoneont
hescr
een
•Or
i
ent
at
i
onofadef
ectdoesnotmat
t
erasi
tdoesont
hepul
seechodi
spl
ay
.
Thedi
sadv
ant
agesar
e
•Def
ectcannotbel
ocat
ed
•Def
ectcannotbei
dent
i
f
i
ed
•Componentsur
f
acesmustbepar
al
l
el
•Ver
t
i
cal
def
ect
sdonotshow
•Pr
ocessmustbeaut
omat
ed
•Mustbeaccesst
obot
hsi
desoft
hecomponent
14.
5 Tandem scanni
ng
Tandem scanni
ngi
susedmai
nl
yt
ol
ocat
edef
ect
sl
y
i
ngper
pendi
cul
art
ot
he
sur
f
ace.I
ti
nv
ol
v
est
heuseoft
woormor
eangl
epr
obesoft
hesame angl
eof
i
nci
denceandf
aci
ng t
hesamedi
r
ect
i
onwi
t
honepr
obeact
i
ngast
het
r
ansmi
t
t
er
andt
heot
her
(
s)asr
ecei
v
er
s
14.
6 Cont
actscanni
ng
Cont
actscanni
ngi
sdef
i
nedbyEN 1330asscanni
ngbymeansofanul
t
r
asoni
c
pr
obe(
s)i
ndi
r
ectcont
actwi
t
ht
heobj
ectunderexami
nat
i
on(
wi
t
horwi
t
hout
coupl
ant
)
.Nor
malat
hi
nf
i
l
m ofcoupl
antbet
weent
hepr
obeandt
het
estsur
f
ace
ser
v
est
obot
ht
r
ansmi
tul
t
r
asoundandt
ol
ubr
i
cat
et
hesur
f
aceandr
educewearon
t
hepr
obef
ace.I
deal
l
yt
heacoust
i
ci
mpedanceoft
hecoupl
antshoul
dbebet
ween
t
hatoft
hepr
obe(
per
spex)andt
hemat
er
i
al
undert
est
14.
7 Gapscanni
ng
I
naccor
dancewi
t
hEN130gapscanni
ngi
sat
echni
quei
nwhi
cht
hepr
obei
snoti
n
di
r
ectcont
actwi
t
ht
hesur
f
aceoft
hespeci
menbuti
scoupl
edt
oi
tt
hr
ougha
col
umnofl
i
qui
d,notmor
et
hanaf
ewwav
el
engt
hst
hi
ck.
14.
8I
mmer
si
ont
est
i
ng
I
mmer
si
ont
est
i
ngi
nv
ol
v
est
het
estobj
ectbei
ngsubmer
gedi
nal
i
qui
d,usual
l
y
wat
erandt
hepr
obebei
ngscannedataf
i
xeddi
st
anceabov
et
hecomponent
.The
wat
erser
v
est
opr
ov
i
deconst
antcoupl
i
ngcondi
t
i
onsandamount
st
oal
ongf
l
ui
d
del
ayl
i
ne.Al
t
hought
hepr
obei
t
sel
fmustbeacompr
essi
onwav
e,
shearwav
escan
be pr
oduced wi
t
hi
nt
he sampl
e byangul
at
i
ons oft
he pr
obe.Thi
st
echni
que
f
r
equent
l
yuses hi
gh f
r
equencypr
obes (
2550 MHz)and f
ocused pr
obes f
or
aut
omat
edi
nspect
i
onsandi
ssui
t
edt
ot
hei
nspect
i
onofcompl
excomponent
s.
Theuseofwheelpr
obes,squi
r
t
erandbubbl
ersy
st
emsar
eal
soconsi
der
edt
obe
i
mmer
si
onsy
st
ems.
Def
ec
14.
9 PhasedAr
r
ayUl
t
r
asoni
cTest
i
ng
Anar
r
ayt
r
ansduceri
ssi
mpl
yonet
hatcont
ai
nsanumberofsepar
at
eel
ement
si
n
asi
ngl
ehousi
ng,
andphasi
ngr
ef
er
st
ohowt
hoseel
ement
sar
esequent
i
al
l
ypul
sed.
A phased ar
r
ay sy
st
em i
s nor
mal
l
y based ar
ound a speci
al
i
zed ul
t
r
asoni
c
t
r
ansducert
hatcont
ai
nsmanyi
ndi
v
i
dualel
ement
s(
t
y
pi
cal
l
yf
r
om 16t
o256)t
hat
canbepul
sedsepar
at
el
yi
napr
ogr
ammedpat
t
er
n.Theset
r
ansducer
smaybe
usedwi
t
hv
ar
i
oust
y
pesofwedges,i
nacont
actmode,ori
ni
mmer
si
ont
est
i
ng.
Thei
rshapemaybesquar
e,r
ect
angul
ar
,orr
ound,andt
estf
r
equenci
esar
emost
commonl
yi
nt
her
angef
r
om 1t
o10MHz.
Phasedar
r
aysy
st
emspul
seandr
ecei
v
ef
r
om mul
t
i
pl
eel
ement
sofanar
r
ay
.These
el
ement
sar
epul
sedi
nsuchawayast
ocausemul
t
i
pl
ebeam component
st
o
combi
newi
t
heachot
herandf
or
m asi
ngl
ewav
ef
r
ontt
r
av
el
i
ngi
nt
hedesi
r
ed
di
r
ect
i
on.Si
mi
l
ar
l
y
,t
he r
ecei
v
erf
unct
i
on combi
nes t
he i
nputf
r
om mul
t
i
pl
e
el
ement
si
nt
oasi
ngl
epr
esent
at
i
on.
Becausephasi
ngt
echnol
ogyper
mi
t
sel
ect
r
oni
cbeam shapi
ngandst
eer
i
ng,i
ti
s
possi
bl
et
ogener
at
eav
astnumberofdi
f
f
er
entul
t
r
asoni
cbeam pr
of
i
l
esf
r
om a
si
ngl
epr
obeassembl
y
,
andt
hi
sbeam st
eer
i
ngcanbedy
nami
cal
l
ypr
ogr
ammedt
o
cr
eat
eel
ect
r
oni
cscans:
Thi
senabl
est
hef
ol
l
owi
ngcapabi
l
i
t
i
es:
1.Sof
t
war
econt
r
olofbeam angl
e,f
ocaldi
st
ance,andbeam spotsi
ze.These
par
amet
er
scanbedy
nami
cal
l
yscannedateachi
nspect
i
onpoi
ntt
oopt
i
mi
ze
i
nci
dentangl
eandsi
gnal
t
onoi
sef
oreachpar
tgeomet
r
y
.
2.Mul
t
i
pl
eangl
ei
nspect
i
on can be per
f
or
med wi
t
h a si
ngl
e,smal
l
,mul
t
i
el
ementpr
obeandwedge,of
f
er
i
ngei
t
hersi
ngl
ef
i
xedangl
esorascan
t
hr
oughar
angeofangl
es.
3.These capabi
l
i
t
i
es pr
ov
i
de gr
eat
erf
l
exi
bi
l
i
t
yf
ori
nspect
i
on ofcompl
ex
geomet
r
i
esandt
est
si
nwhi
chpar
tgeomet
r
yl
i
mi
t
saccess.
4.Mul
t
i
pl
exi
ngacr
ossmanyel
ement
sal
l
owsmot
i
onl
esshi
ghspeedscans
f
r
om asi
ngl
et
r
ansducerposi
t
i
on.Mor
et
hanonescanmaybeper
f
or
med
f
r
om asi
ngl
el
ocat
i
onwi
t
hv
ar
i
ousi
nspect
i
onangl
es.
Adv
ant
ages
Ul
t
r
asoni
cphasedar
r
aysy
st
emscanpot
ent
i
al
l
ybeempl
oy
edi
nal
mostanyt
est
wher
econv
ent
i
onalul
t
r
asoni
cf
l
aw det
ect
or
shav
et
r
adi
t
i
onal
l
ybeenused.Wel
d
i
nspect
i
onandcr
ackdet
ect
i
onar
et
hemosti
mpor
t
antappl
i
cat
i
ons,andt
hese
t
est
sar
edoneacr
ossawi
der
angeofi
ndust
r
i
esi
ncl
udi
ngaer
ospace,power
gener
at
i
on,pet
r
ochemi
cal
,met
albi
l
l
etand t
ubul
argoods suppl
i
er
s,pi
pel
i
ne
const
r
uct
i
on and mai
nt
enance,st
r
uct
ur
almet
al
s,and gener
almanuf
act
ur
i
ng.
Phasedar
r
ay
scanal
sobeef
f
ect
i
v
el
yusedt
opr
of
i
l
er
emai
ni
ng wal
lt
hi
cknessi
n
cor
r
osi
onsur
v
eyappl
i
cat
i
ons.
Thebenef
i
t
sofphasedar
r
ayt
echnol
ogyov
erconv
ent
i
onal
UTcomef
r
om i
t
sabi
l
i
t
y
t
ousemul
t
i
pl
eel
ement
st
ost
eer
,f
ocusandscanbeamswi
t
hasi
ngl
et
r
ansducer
assembl
y
.Beam st
eer
i
ng,commonl
yr
ef
er
r
edt
osect
or
i
alscanni
ng,canbeused
f
ormappi
ng component
satappr
opr
i
at
eangl
es.Thi
scangr
eat
l
ysi
mpl
i
f
yt
he
i
nspect
i
onofcomponent
swi
t
hcompl
exgeomet
r
y
.Thesmal
lf
oot
pr
i
ntoft
he
t
r
ansducerandt
heabi
l
i
t
yt
osweept
hebeam wi
t
houtmov
i
ngt
hepr
obeal
soai
ds
i
nspect
i
onofsuchcomponent
si
nsi
t
uat
i
onswher
et
her
ei
sl
i
mi
t
edaccessf
or
mechani
calscanni
ng.Sect
or
i
alscanni
ngi
sal
sot
y
pi
cal
l
yusedf
orwel
di
nspect
i
on.
Theabi
l
i
t
yt
ot
estwel
dswi
t
hmul
t
i
pl
eangl
esf
r
om asi
ngl
epr
obegr
eat
l
yi
ncr
eases
t
hepr
obabi
l
i
t
yofdet
ect
i
onofanomal
i
es.El
ect
r
oni
cf
ocusi
ngper
mi
t
sopt
i
mi
zi
ng
t
hebeam shapeandsi
zeatt
heexpect
eddef
ectl
ocat
i
on,aswel
lasf
ur
t
her
opt
i
mi
zi
ngpr
obabi
l
i
t
yofdet
ect
i
on.Theabi
l
i
t
yt
of
ocusatmul
t
i
pl
edept
hsal
so
i
mpr
ov
est
heabi
l
i
t
yf
orsi
zi
ngcr
i
t
i
caldef
ect
sf
orv
ol
umet
r
i
ci
nspect
i
ons.Focusi
ng
can si
gni
f
i
cant
l
yi
mpr
ov
e si
gnal
t
onoi
se r
at
i
oi
n chal
l
engi
ng appl
i
cat
i
ons,and
el
ect
r
oni
cscanni
ngacr
ossmanygr
oupsofel
ement
sal
l
owsf
orCScani
magest
o
bepr
oducedv
er
yr
api
dl
y
.
Thepot
ent
i
aldi
sadv
ant
agesofphasedar
r
aysy
st
emsar
easomewhathi
ghercost
andar
equi
r
ementf
oroper
at
ort
r
ai
ni
ng,howev
ert
hesecost
sar
ef
r
equent
l
yof
f
set
by t
hei
rgr
eat
erf
l
ex
i
bi
l
i
t
yandar
educt
i
oni
nt
het
i
mer
equi
r
edt
oper
f
or
m agi
v
en
i
nspect
i
on.
14.
10Ti
meofFl
i
ghtDi
f
f
r
act
i
on
I
nt
r
oduct
i
on
TheTi
meof
Fl
i
ghtDi
f
f
r
act
i
on(
TOFD)t
echni
quei
sr
api
dl
ygai
ni
ngi
mpor
t
anceasa
st
andal
onei
nspect
i
ont
echni
que.TheTOFDt
echni
quei
sanadv
ancedul
t
r
asoni
c
i
nspect
i
ont
echni
quet
hatf
ul
f
i
l
saneedf
orr
el
i
abl
ei
nspect
i
ons.I
ti
sapower
f
ul
t
echni
quebecausei
tcansi
mul
t
aneousl
ydet
ectandsi
zedef
ect
s.TOFDi
snow
r
out
i
nel
yusedi
nawi
de r
ange ofappl
i
cat
i
ons such as i
nspect
i
on ofpi
pi
ng
and pr
essur
e v
essel
s. Whatt
y
peofi
nf
or
mat
i
onwi
l
lTOFDgener
al
l
ypr
ov
i
de?A
r
out
i
nei
nspect
i
onpr
ov
i
dest
heoper
at
orwi
t
ht
hef
ol
l
owi
ngi
nf
or
mat
i
on:




l
ocat
i
onofi
ndi
cat
i
onsal
ongt
hewel
d
posi
t
i
onofi
ndi
cat
i
onswi
t
hr
espectt
ot
hescanni
ngsur
f
ace(
dept
h
i
nf
or
mat
i
on)
t
hr
ought
hi
cknessex
t
ent
,i
fex
ceedi
ngacer
t
ai
nv
al
ue(
t
y
pi
cal2mm)
,
whi
chmeanst
hatpor
osi
t
yandsl
agwi
l
lgener
al
l
ybedet
ect
edas
"
i
ndi
cat
i
onswi
t
houtmeasur
abl
ehei
ght
"
i
nf
or
mat
i
onon"
embedded"or"
sur
f
acebr
eaki
ng"char
act
erofadef
ect
I
nf
or
mat
i
on on t
he t
y
pe ofdef
ecti
sl
i
mi
t
ed,si
mi
l
art
o bot
h manualand
mechani
sedul
t
r
asoni
ci
nspect
i
on.Thi
si
snotnecessar
i
l
yapr
obl
em,
becausef
r
om
af
r
act
ur
e mechani
cspoi
ntofv
i
ew,manydef
ect
st
hatar
enor
mal
l
yr
egar
dedas
v
ol
umet
r
i
c,suchassl
agi
ncl
usi
ons,maybeshar
penought
obeabl
et
oactas
cr
acki
ni
t
i
at
or
s.Al
so,
t
hi
saspecti
scompensat
ed,
t
oacer
t
ai
next
ent
,
byt
heabi
l
i
t
y
ofTOFDt
odi
st
i
ngui
shbet
ween"
def
ect
swi
t
houtmeasur
abl
ehei
ght
"and"
def
ect
s
wi
t
hmeasur
abl
ehei
ght
"
.
Thi
s,i
ncombi
nat
i
onwi
t
ht
hehi
ghpr
obabi
l
i
t
yofdet
ect
i
on(
POD)andal
ow f
al
se
cal
lr
at
e(
FCR)
,
makesTOFDav
al
uabl
et
oolf
orr
out
i
neNDT,
i
nt
hesenseof"
Good
Wor
kmanshi
pev
al
uat
i
onsuppor
t
edbyf
r
act
ur
emechani
csconsi
der
at
i
ons"
.
Recent
dev
el
opment
s ofcodes and def
ectaccept
ance st
andar
ds f
oruse wi
t
ht
he
t
echni
quesuppor
tt
hi
st
endencyandi
sr
esul
t
i
ngi
nawi
deraccept
anceev
er
yy
ear
.
Apar
tf
r
om t
he gr
owi
ng r
eal
i
sat
i
on byt
he mar
kett
hatTOFD of
f
er
s uni
que
adv
ant
ages,t
hesedev
el
opment
sar
e al
sost
i
mul
at
edbyt
her
eal
i
sat
i
onoft
hef
i
v
e
mai
nt
opi
cs:




Equi
pmenti
mpr
ov
ement
Tr
ansducerper
f
or
mancei
mpr
ov
ement
I
ni
t
i
at
i
v
est
oest
abl
i
sht
hequal
i
f
i
cat
i
onofTOFDoper
at
or
s
Accept
anceofTOFDi
nwel
dandv
essel
i
nspect
i
on

I
mpl
ement
at
i
onofnewcodesandst
andar
ds
Shor
ti
nt
r
oduct
i
ont
ot
het
echni
que
Thepr
i
nci
pl
eoft
heTOFDt
echni
quei
sbasedonmappi
ngoft
heposi
t
i
onoft
he
edgesofdef
ect
s.Thi
si
si
nmar
kedcont
r
astwi
t
hconv
ent
i
onalul
t
r
asoni
cs,whi
ch
r
el
i
esont
heampl
i
t
udeofspecul
arr
ef
l
ect
i
onsr
ecei
v
edf
r
om def
ect
s.Todet
er
mi
ne
t
heposi
t
i
onoft
hedef
ectedges,awi
debeam t
r
ansmi
t
t
erpr
obei
spl
acedonone
si
deoft
hewel
dunderi
nspect
i
on.Ani
dent
i
cal
r
ecei
v
erpr
obei
spl
acedont
heot
her
si
deoft
hewel
d(
f
i
gur
e1)
.I
nt
hecaseofaf
l
awl
esswel
d,t
her
el
ev
antul
t
r
asoni
c
si
gnalwi
l
lconsi
stofaso cal
l
ed "
l
at
er
alwav
e"
,cor
r
espondi
ngt
ot
hedi
r
ect
sur
f
acepat
hbet
weent
r
ansmi
t
t
erandr
ecei
v
er
,andabackwal
lecho.Bet
weent
he
l
at
er
alwav
eandt
hebackwal
lechot
her
ewi
l
lbenosi
gnal
s.I
fdef
ect
sar
epr
esent
i
nt
hewel
d,howev
er
,t
heul
t
r
asoni
cwav
eswi
l
lbedi
f
f
r
act
edbyt
heedgesoft
he
def
ect
s.Thedept
hoft
hedef
ectedgecanbecal
cul
at
edf
r
om t
het
i
me off
l
i
ghtof
t
hecor
r
espondi
ngul
t
r
asoni
cwav
e.Def
ecthei
ghtcanber
eadi
l
ymeasur
edby
subt
r
act
i
onoft
hedept
hofl
owerandhi
gherdef
ectedge.
t
hepr
i
nci
pl
eofTOFDi
nspect
i
onona
wel
dedpl
at
e
Li
keanyot
hert
echni
que,
TOFDal
sohasi
t
sl
i
mi
t
at
i
ons.I
ngener
alt
het
echni
quei
s
l
esssui
t
abl
ef
orcoar
segr
ai
nedmat
er
i
al
ssuchasmanyt
y
pesofaust
eni
t
i
cst
eel
.
I
nspect
abi
l
i
t
ywi
t
hTOFDi
susual
l
yassessedonacaseby
casebasi
s.I
naddi
t
i
on,
i
nspect
i
onr
el
i
abi
l
i
t
ycl
oset
ot
hescanni
ngsur
f
acei
shamper
edbyt
hepr
esenceof
t
hel
at
er
alwav
e,whi
chmayobscur
edef
ect
spr
esenti
nt
hi
sar
ea.Speci
al
i
sed
sof
t
war
eal
gor
i
t
hmscanbeusedt
omi
ni
mi
set
hi
sef
f
ect
.Si
mi
l
ar
l
y
,smal
ldef
ect
s
l
ocat
edv
er
ycl
oset
ot
her
ootoft
he wel
d maysomet
i
mesbeobscur
edby
i
r
r
egul
ar
i
t
i
esi
nt
her
ootsuchasmi
smat
ch.
Gener
alaccept
anceoft
heTOFD t
echni
quewi
l
lonl
ybepossi
bl
ei
fi
ti
sal
so
pr
oper
l
yembeddedi
ncodesandst
andar
ds.Wi
t
hmor
eandmor
eexper
i
enced
gat
her
edt
hepot
ent
i
al
f
ort
het
echni
quei
sr
api
dl
yi
ncr
easi
ng.Pr
esentdev
el
opment
si
nt
hecodes,
def
ect
accept
ancest
andar
dsandper
sonnel
qual
i
f
i
cat
i
onssuppor
tt
hi
st
endency
.
Thef
ol
l
owi
ngmai
npr
i
nci
pl
esdescr
i
beTOFD:
 Twoangl
ebeam pr
obes(
usual45°
)ar
epl
acedasat
r
ansmi
t
t
er
r
ecei
v
er
ar
r
angementandar
econnect
edt
oget
her(f
i
g)
.Thedi
st
anceoft
hepr
obesi
s
cal
cul
at
edaccor
di
ngt
ot
hewal
l
t
hi
ckness.
 Longi
t
udi
nalwav
esar
eusual
l
yappl
i
ed.Thesoundbeam spr
eadi
sl
ar
get
o
maxi
mi
zet
heext
entoft
hescan.
 TheAscani
nt
heabov
ef
i
gur
eshowst
hesocal
l
edl
at
er
al
wav
e,
t
hebackwal
l
echoesandbet
weenbot
hsi
gnal
sot
hersi
gnal
scanpossi
bl
yappear
,
whi
ch
canoccurduet
oi
nhomogenei
t
y
.TheAScani
snotr
ect
i
f
i
edi
nt
heTOFD
t
echni
que.
 TOFDt
echni
quei
sal
way
sappl
i
edwi
t
hi
magi
ngmet
hods(
Fi
gur
eat
t
achedabov
e)
.
15.
0 Pr
esent
at
i
on
Thef
l
awdet
ect
ororUTsetsendsul
t
r
asoundener
gyi
nt
ot
estmat
er
i
al
sandsome
oft
hi
sr
et
ur
nt
ot
hesett
obepr
esent
edasi
nf
or
mat
i
ononaCRTscr
een.Thi
si
san
Ascandi
spl
aywi
t
ht
heampl
i
t
udeofsi
gnal
sdi
spl
ay
edasaf
unct
i
onoft
i
meor
di
st
ance.Ther
ear
eot
herway
sofpr
esent
i
ngt
hei
nf
or
mat
i
on.
A,
B,
C&DSCANNI
NGSYSTEMS
15.
1 As
c
an
Thi
si
soneoft
hemos
tc
ommons
y
s
t
e
msi
n us
ef
orma
nua
lul
t
r
a
s
oni
c
i
ns
pe
c
t
i
on.I
tdi
s
pl
a
y
st
her
e
f
l
e
c
t
e
de
ne
r
gy a
ss
i
gna
l
s on a CRT.The
hor
i
z
ont
a
la
x
i
sont
heCRTr
e
pr
e
s
e
nt
se
l
a
ps
e
dt
i
meordi
s
t
anc
ea
ndt
he
x
i
sr
e
pr
e
s
e
nt
ss
i
gna
lampl
i
t
udeors
v
e
r
t
i
c
a
la
ounde
ne
r
gyr
e
t
ur
ni
ngt
ot
he
f
e
c
tf
r
om
pr
obe
.Thi
ss
y
s
t
e
mc
a
npr
ov
i
dea
ni
ndi
c
at
i
onont
hes
i
z
eofade
s
i
gna
l
a
mpl
i
t
ude
,t
hede
f
e
c
tl
oc
a
t
i
on,
f
r
om t
hepos
i
t
i
onoft
hes
i
gna
l
ont
he
t
i
me
ba
s
e
,a
nd t
hes
i
gna
ls
ha
pea
ndbe
hav
i
or
,
onmov
e
me
ntoft
hepr
obe
,
c
a
ni
ndi
c
a
t
ede
f
e
c
tt
y
pe
.Thedi
s
a
dv
a
nt
a
ge
soft
hi
ss
y
s
t
e
ma
r
et
ha
tt
he
s
i
gna
l
sr
e
qui
r
ei
nt
e
r
pr
e
t
a
t
i
on,
whi
c
hme
anst
ha
tmor
es
k
i
l
li
sr
e
qui
r
e
df
or
ope
r
a
t
i
on.Thea
dv
a
nt
a
ge
soft
hi
ss
y
s
t
e
ma
r
ei
t
spor
t
a
bi
l
i
t
ya
ndl
e
s
st
i
me
i
nv
ol
v
e
di
ns
e
t
t
i
ngup.
15.
2 Bs
c
ans
y
s
t
e
m
Th
e Bs
c
a
ns
y
s
t
e
m p
r
ov
i
d
e
su
s wi
t
hac
r
os
s
s
e
c
t
i
on
a
lv
i
e
w oft
h
e
ma
t
e
r
i
a
lu
n
d
e
rt
e
s
tb
ys
c
a
n
n
i
n
g t
h
ep
r
ob
ea
c
r
os
st
h
es
u
r
f
a
c
e
(
s
ome
t
i
me
sa
th
i
g
hs
p
e
e
d
)
.Th
ei
ma
g
ei
sr
e
t
a
i
n
e
du
s
i
n
gd
i
g
i
t
a
l
r
e
c
or
d
i
n
g
,g
i
v
i
n
gap
e
r
ma
n
e
n
tr
e
c
or
d oft
h
eu
l
t
r
a
s
on
i
cd
a
t
a
.Th
e
a
mp
l
i
t
u
d
e of t
h
er
e
c
e
i
v
e
rr
e
c
e
i
v
e
ds
i
g
n
a
li
sr
e
p
r
e
s
e
n
t
e
db
yt
h
e
b
r
i
g
h
t
n
e
s
soft
h
ei
ma
g
ea
n
dt
h
es
y
n
c
h
r
on
i
s
a
t
i
onoft
h
emov
e
me
n
tof
t
h
ep
r
ob
ea
n
dt
h
ed
i
s
p
l
a
yc
a
ng
i
v
eat
r
u
er
e
p
r
e
s
e
n
t
a
t
i
onoft
h
es
i
z
eof
t
h
ed
e
f
e
c
t
.
15.
3 Cs
c
ans
y
s
t
e
m
Thi
ssy
st
em gi
v
esusapl
anv
i
ewoft
hes
c
anned ar
ea,showi
ng def
ect
s as
cont
r
ast
i
ngar
eas
,onapr
i
nt
outorpl
ot
t
i
ngs
y
s
t
em t
hati
ssy
nchr
oni
sedwi
t
h
t
hepr
obe'
smov
ementasi
tt
r
av
er
s
esov
ert
hemat
er
i
al
.Thebi
gadv
ant
ageof
t
hes
y
s
t
em i
sani
ns
t
antper
manentr
ec
or
d.Thedi
s
adv
ant
agesar
et
her
ei
sno
i
ndi
c
at
i
onofdef
ec
tdept
horor
i
ent
at
i
onands
et
t
i
ngupt
hes
y
s
t
em c
anbet
i
me
c
ons
umi
ng
15.
4
TheDscan
TheDscangi
v
esasi
dev
i
ewoft
hedef
ectseenf
r
om av
i
ewpoi
ntnor
malt
ot
heB
scan.I
ti
susual
l
yaut
omat
ed,andshowst
hel
engt
h,dept
handt
hr
ought
hi
ckness
ofadef
ect
.The Dscanshoul
dnotbeconf
usedwi
t
ht
hedel
t
at
echni
que.
16.
0 I
dent
i
f
y
i
ngf
l
awsi
nbut
twel
ds
I
ti
snotal
way
seasyt
oi
dent
i
f
yadef
ect
,butbynot
i
ngi
t
sposi
t
i
oni
nt
hewel
dand
mov
i
ngt
hepr
obear
oundt
hedef
ectandwat
chi
ngt
hechangi
ngsi
gnalont
he
scr
eeny
oucancomet
oar
easonabl
yaccur
at
econcl
usi
on.Knowl
edgeoft
he
wel
di
ng pr
ocess i
s essent
i
al
,as i
s knowl
edge oft
he wel
d pr
epar
at
i
on,wel
d
di
mensi
ons,si
zeoft
hegapandot
herf
act
or
s.Sl
agi
sunl
i
kel
yi
naTI
Gwel
dand
l
ackofsi
dewal
lf
usi
oni
snotl
i
kel
yi
nt
hemi
ddl
eoft
hewel
dmet
al
.Cr
acksar
e
mor
el
i
kel
yi
nt
hi
ckerwel
dst
hani
nt
hi
nnerwel
dsandf
usi
ondef
ect
sar
emor
el
i
kel
y
i
naut
omat
i
cwel
di
ngpr
ocessest
hani
nmanual
.I
naddi
t
i
ont
heshape,ampl
i
t
ude
andt
i
mespr
eadofar
ef
l
ect
orasr
epr
esent
edont
hescr
een,cangi
v
e cl
uesast
o
t
hei
dent
i
t
yofaf
l
aw.Wet
al
kofaSpecul
arr
ef
l
ect
or
,
t
hati
swi
t
hami
r
r
orl
i
kef
ace,
wher
eal
lt
hesoundi
sr
ef
l
ect
edbackt
ot
hesour
ceofener
gy
.Pr
ov
i
di
ngt
hati
s,
t
he
pr
obeandf
l
aw ar
ecor
r
ect
l
yor
i
ent
at
ed.Asi
dewal
lf
usi
onf
l
aw i
snear
estt
ot
hi
s
i
deal
.
Howev
er
,att
heot
herext
r
eme,por
osi
t
ycanbeconsi
der
edasal
ar
genumberof
smal
lspher
i
calr
ef
l
ect
or
swhi
chcauset
heener
gyt
or
ef
l
ectev
er
y
wher
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s:
16.
1 SCANNI
NGPATTERNS
Fora
ngl
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c
a
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s
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ommonpat
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e
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,
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e
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omes
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andar
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i
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s ma
ni
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l
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.Or
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t
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t
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ar
i
ousmaxi
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ma.Si
mi
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ht
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av
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at
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onal
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ckl
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ar
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at
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.Per
hapswi
t
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ot
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orshor
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st
ancesl
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hanbeam wi
dt
h.
19.
0 ULTRASONI
CTESTI
NGOFCASTI
NGS
GENERAL
Theul
t
r
a
s
oni
ct
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s
t
i
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at
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i
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a
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omebyus
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TECHNI
QUE
Whens
ear
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as
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ni
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uct
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eet
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es
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omponenti
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i
f
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c
at
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eat
ot
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t
.
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obet
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ect
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pos
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oft
es
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ens
i
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i
v
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yt
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e,
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t
hodofs
c
a
nni
ng.
Thei
ns
t
r
uc
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i
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uc
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t50woul
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o hav
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ompany name,a uni
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sname and s
i
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t
ec
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c
al r
ef
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enc
e number
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he or
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hor
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s
i
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i
gnat
ur
e.
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s
ta
r
e
a
Thet
es
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nv
ol
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t
i
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as
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i
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us
ts
ec
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hi
s
s
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pec
i
f
i
ed.
Ac
t
i
onst
obet
ak
e
n
Whe
nde
f
e
c
t
sa
r
ef
oundi
tma
yber
e
qui
r
e
dt
ha
tt
hede
f
e
c
t
sa
r
er
e
por
t
e
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e
.
g.onadi
a
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a
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sa wr
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e
n de
s
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pt
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he c
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e
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t
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or
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ot
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t
sf
ound.I
fde
f
e
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t
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et
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f
e
c
t70 i
nf
or
ma
t
i
ont
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e
por
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r
e
por
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e
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c
ont
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nt
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t
i
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e
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f
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pe
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i
z
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a
t
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r
a
la
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ongi
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udi
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pos
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oni
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a
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oda
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umse
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.
Pur
poseoft
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Thi
ss
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t
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h def
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s r
ender t
he c
as
t
i
ng
r
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abl
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pment
Thi
ssect
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ei
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or
mat
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l
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ect
or
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r
equencyofpr
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peofcoupl
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br
at
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ocksandr
ef
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encebl
ockst
o
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i
t
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e.
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t
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r
om t
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l
atbot
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om hol
er
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er
ence
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ef
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ect
ort
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i
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l
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ai
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h
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n
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v
a
n
tn
a
t
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on
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l
s
t
a
n
d
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r
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a
mp
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ewr
i
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e
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t
e
pb
ys
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pc
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e
:
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acebyr
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i
nganyl
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ust
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r
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acedef
ect
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i
br
at
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hes
c
r
e
e
nont
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a
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or
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ndt
heA2
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al
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at
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e
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t
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a
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nt
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ta
r
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i
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s
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r
e
a
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t
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l
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ra
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e
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ect
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er
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ai
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Pur
poseoft
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ec
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el
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ec
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f
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t
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a
r
g
e
rt
h
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nt
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l
t
r
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wh
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et
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r
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od
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t
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p
l
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l
t
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dd
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f
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ou
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d b
es
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z
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i
n
gt
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e
ma
x
i
mu
ma
mp
l
i
t
u
d
et
e
c
h
n
i
qu
e
.
 Pr
e
pa
r
e a ne
a
tc
onc
i
s
er
e
por
t gi
v
i
ng de
t
a
i
l
s of t
he c
a
s
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i
ng'
s
i
de
nt
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f
i
c
a
t
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s
t
a
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a
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g
na
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d
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t
et
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p
or
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ds
t
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t
ey
ou
rr
e
l
e
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n
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u
a
l
i
f
i
c
a
t
i
o
n
s
.
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estpr
ocedur
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Thi
swoul
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nganyr
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r
tf
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om t
het
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ot
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i
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c
or
di
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oc
l
i
ent
'
s
r
equi
r
ement
s
.
DEFECTSI
NCASTI
NGS
The i
nt
e
r
pr
e
t
at
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on of de
f
e
c
t
si
n c
as
t
i
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nv
ol
v
e
sk
nowl
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pe
r
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t
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ta
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r
om
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n s
ome s
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om t
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l
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t
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st
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ht
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ti
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k
e
l
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,
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r
ea
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af
e
woft
het
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pe
sofde
f
e
c
t
sf
oundi
nc
a
s
t
i
ngs
:
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ncl
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I
ncl
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ef
or
medf
r
om l
umpsoft
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appeds
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i
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i
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nt
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ar
i
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i
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es
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ent
at
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nl
ar
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mal
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at
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ent
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oundbeam,asi
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est
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ough.Whenus
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as
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ft
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at
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our
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,Thi
scausesasi
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hes
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gnal
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r
om t
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ar
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er
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or
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.Thes
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om mul
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om t
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l
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er of s
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gnal
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r
om t
he def
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t
s has a c
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t
ant
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hangi
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os
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ur
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l
us
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ons wi
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lgi
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ongers
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gnal
s de
pe
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hape
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i
z
e and
or
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e
nt
at
i
on.
Se
gr
e
gat
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on
Whe
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l
l
oy
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r
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ot
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t
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omeoft
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t
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t
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ft
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c
ous
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ur
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ns
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a
s
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e
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st
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e
n
s
i
t
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v
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t
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oft
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i
pme
n
ti
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i
gh
.
Af
l
ake
Thi
sde
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e
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sde
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e
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us
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ur
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a
c
e
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s
us
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l
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onofaLev
el
2orLev
el
3per
son.Al
ev
el
1per
sonhasdemonst
r
at
edcompet
encet
o:
 Setupequi
pmentandcar
r
youtt
est
s;
 Recor
dandcl
assi
f
yt
her
esul
t
si
nt
er
msofwr
i
t
t
encr
i
t
er
i
a
Lev
el2
Thi
sl
ev
el
qual
i
f
i
esper
sonnel
t
oper
f
or
m anddi
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ectNDTaccor
di
ngt
oest
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i
shedorr
ecogni
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pr
ocedur
esandhasdemonst
r
at
edcompet
encet
o:
 Chooset
het
echni
quef
ort
het
estmet
hodused;
 Per
f
or
m andsuper
v
i
set
het
est
 I
nt
er
pr
et
,
ev
al
uat
eandr
epor
tr
esul
t
saccor
di
ngt
oappl
i
cabl
est
andar
ds,
codesor
speci
f
i
cat
i
ons;
 Def
i
net
hel
i
mi
t
at
i
onsoft
het
est
i
ngmet
hodf
orwhi
cht
hequal
i
f
i
cat
i
oncov
er
s;
 Under
st
andandt
r
ansf
or
m NDTst
andar
dsandspeci
f
i
cat
i
onsi
nt
opr
act
i
cal
t
est
i
ng
i
nst
r
uct
i
onsadapt
edt
ot
heact
ual
wor
ki
ngcondi
t
i
ons.
Lev
el3
Thi
sl
ev
el
qual
i
f
i
esper
sonnel
t
odi
r
ectanyNDToper
at
i
onf
orwhi
cht
heyar
ecer
t
i
f
i
cat
edand:
 Assumef
ul
l
r
esponsi
bi
l
i
t
yf
orat
estf
aci
l
i
t
yandst
af
f
;
 Est
abl
i
shand/
orv
al
i
dat
eNDTi
nst
r
uct
i
onsorpr
ocedur
es;
 I
nt
er
pr
etcodes,
st
andar
ds,
speci
f
i
cat
i
onsandpr
ocedur
es;
 Desi
gnat
edt
hepar
t
i
cul
art
estmet
hods,
t
echni
quesandpr
ocedur
est
obeused.
Pr
eexami
nat
i
onRequi
r
ement
s
Lev
el1andLev
el2:Ther
ear
emandat
or
ymi
ni
mum pr
eappr
ov
al
t
r
ai
ni
ngr
equi
r
ement
swhi
char
e
gi
v
eni
nt
hePCNr
equi
r
ement
sdocument
s.
Pr
eexami
nat
i
ont
r
ai
ni
ngcour
sesmustbev
al
i
dat
edbyt
heBr
i
t
i
shI
nst
i
t
ut
eofNonDest
r
uct
i
v
e
Test
i
ngandneedt
ocov
ert
hesy
l
l
abusov
eradesi
gnat
edmi
ni
mum numberofhour
s.
Document
edi
nhouset
r
ai
ni
ngmayaccountf
orupt
oonet
hi
r
doft
her
equi
r
edt
r
ai
ni
nghour
s.The
candi
dat
eal
sohast
odemonst
r
at
epr
act
i
cal
exper
i
encei
nl
i
newi
t
ht
her
equi
r
ement
sofPCN.
Lev
el3:Thecandi
dat
eshav
et
woaccessr
out
esav
ai
l
abl
ewhi
char
eshowni
nt
hePCN
r
equi
r
ement
sdocument
s.Bot
ht
r
ai
ni
ngandexper
i
encer
equi
r
ement
sdependuponacademi
c
backgr
ound.Not
e:
Amat
ur
ecandi
dat
er
out
ei
sav
ai
l
abl
e
Exami
nat
i
ons
Theexami
nat
i
onconsi
st
sofgener
al
t
heor
y
,
speci
f
i
ct
heor
yandpr
act
i
cal
par
t
sdependanton
l
ev
el
andt
y
peofexami
nat
i
on.
Byhol
di
ngot
herPCNqual
i
f
i
cat
i
onscandi
dat
esmaybeel
i
gi
bl
ef
orexempt
i
ons.
Fol
l
owi
nganexami
nat
i
on,
ar
esul
t
snot
i
cewi
l
l
bei
ssued:
t
hi
scount
sasev
i
denceofPCN
cer
t
i
f
i
cat
i
onf
oraper
i
odof42day
s.Thecer
t
i
f
i
cat
ewi
l
l
f
ol
l
owt
her
esul
t
snot
i
cewi
t
hi
n21day
s.
Wher
et
hecandi
dat
ei
sunsuccessf
ul
,
oner
et
estmaybeal
l
owedpr
ov
i
di
ngt
heper
cent
agegr
ades
ar
enotl
owert
hant
hegr
adesr
equi
r
edbyPCN.