HF_TechTalk

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High Latitude HF Comms Testing
LT Mike Grochowski
Bill Jankowski
USCG RDC
What’s the Frequency, Kenneth?
•WiFi – 2.4 GHz (2400 MHz)
•AM Radio - ~1000 kHz (~1
MHz)
•FM Radio - ~100 MHz (0.1
GHz)
•Cell Phones
(850/900/1,800/1,900 MHz)
What Does HF Mean?
HF stands for HIGH FREQUENCY
These are the frequencies from 1.8* to 30 MHz
or the 160 meter to 10 meter bands.
HF is also known as shortwave.
*160m is actually a Mid Frequency (MF) band but it is included in the
Amateur HF bands for ease of discussion.
Ok, if HF is so Great, why doesn't everyone
use it??
–HF propagation is impacted by the actions of the Sun via
“Sunspots”
–Data throughputs from 75bps->19.2kbps under poor-> very
good conditions,
–From 2-10MHz, the noise environment can rise 33 – 70dB
ABOVE thermal noise (kTB) due to manmade and
atmospherics„ (fluorescent lights, T- storms, fish tanks,
electric fences, Xmas lights, old electric motors, etc)
–Common perception is that data rates are “low” and
antennas are LARGE
•Breaking NEWS: MIL-STD-188-110C Appendix D Data
Waveform Suite (approved Sept 2011) supports HF
Channel bandwidths ranging from 3 – 24KHz in 3kHz
steps, allowing 75bps -> 120Kbps.
How is HF different other
communications methods?
•No “machine” or infrastructure is used. HF
Takes advantage of atmospherics
•Allows communication beyond line of sight
WITHOUT Satellites or repeaters. Links can be a
couple of hundred miles to over several
thousand miles.
•Propagation is strongly effected by solar
activity.
•Several communication modes are available to
use. SSB, CW, RTTY, SSTV, Digital, AM
Hearing Signals Out
of Thin Air
The Role of Sol
How the Sun Opens
and Closes The Bands
Why HF Works
(The Atmosphere)
The Earth’s atmosphere is made up
of several layers or regions.
D-Layer – Strong absorber of
low-frequency HF energy during
the day
E-Layer – Reflects mid
frequencies of HF (10-30 MHz)
during the day
F-Layer – Strong reflector of
lower-frequency HF
Radio waves change direction when they enter
the ionosphere
Sunspots / Solar Activity
•More sunspots, the higher the ionization
of the F2 Layer
–11 year cycle
•Solar storms (intense cosmic activity) can
change the critical frequency in a matter
of minutes -> hrs
– One minute the link is fine, in a matter of
minutes, its GONE
•Sunspot maximum - 10,000miles
commonplace using 10watts or less with
frequencies in the 20 – 30MHz range.
–Sunspot Activity has stayed well below
maximum
•During short summer evenings, the MUF
can stay above 14 MHz and it can support
communications to some point in the
world around the clock.
–Similarly, during long winter evenings, MUF
plummets and HF Distances shorten
Propagation
There are three basic types of
propagation of HF radio signals:
1.Sky-wave
2.Ground wave
3.High Angle Radiation (NVIS)
Sky-Wave
Provides Single
(<4000km) or Multihop (7 hops,
15,000km)
communications
via ionospheric
reflections
*
* Very, very old picture – D Layer attenuates; it’s the E and F layers that reflect
The Gray Line
The transition are
between daylight
and darkness is
called the gray
line.
This area offers
some unique and
special
propagation to the
radio operator.
Ground Wave
Ground wave is the
signal that radiates
close to the ground
from the Earth’s
surface up to the
lower atmosphere or
troposphere and is
reflected or diffracted
by the terrain.
- ~200-300 NM
NVIS -
Near Vertical Incidence Sky-wave
Like squirting a
hose at the ceiling,
this technique
allows you to
blanket your
signals over a
significant area
close to your
station.
OK, Physics, Great – Why does the USCG
Care?
GMDSS – Global Maritime Distress and Safety System
Uses DSC (Digital Selective Calling) tied to ship’s MMSI
GOTHAM and COTHEN
HF ALE (Automated Link Establishment) networks
HF Secure Voice Network
Got it.
Why does HEALY 1403 care?
RDC study of existing Alaska HF sites identified areas where
coverage could be improved
Temporary deployment to Barrow this summer
Considering additional fixed sites
Multiple Measurements using existing fixed sites and Healy
allow for better modeling in future efforts
More about HF
Amateur Radio
ARRL Web Site -http://www.arrl.org/what-s-ham-radio
ARRL PowerPoint “Discover The Magic of HF Radio”
http://www.barriearc.com/CBSS_ARES_files/HF-Radio.pdf
http://www.emergencyradio.ca/course/HF-Radio.ppt
Low Band Dx‟ing – probably the best source of ALL THINGS HF you‟ll ever need
http://vss.pl/lf/00.pdf
HF Propagation and Propagation Prediction
– VOACAP Website
http://www.astrosurf.com/luxorion/qsl-perturbation6.htm
HF Radiation - Choosing the Right Frequency
http://www.weather.nps.navy.mil/~psguest/EMEO_online/module3/module_3_2b.html
Learning about Space Weather and Predicting HF Propagation
http://www.spacew.com/
HFALE
http://www.navymars.org/central/reg4/al/ALE%20Introduction.pdf
Useful HF Noise Models complete with Formulas
http://ftp.rta.nato.int/public//PubFullText/RTO/TR/RTO-TR-IST-050///TR-IST-050-02.pdf
NVIS
Questions?
Publications
ARRL General
Class License
Manual
http://www.arrl.org/catalog/lm
Morse Code
Study Materials
http://www.arrl.org/catalog/lm
Publications
ARRL Handbook
http://www.arrl.org/catalog/?item=9280
Publications
ARRL Antenna Book
http://www.arrl.org/catalog/?item=9043
Publications
ON4UN's Low-Band DXing
Antennas, Equipment and
Techniques for
DXcitement on 160, 80 and 40m
http://www.arrl.org/catalog/7040/
Publications
The Complete DX'er
by Bob Locher, W9KNI
http://www.arrl.org/catalog/?item=9073
Publications
On the Air with Ham
Radio
By Steve Ford, WB8IMY
http://www.arrl.org/catalog/?item=8276
Publications
RF Exposure and
You
By Ed Hare, W1RFI
http://www.arrl.org/catalog/?item=6621
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