AN INTRODUCTION
TO WSJT
Let’s go fishing, you never know what
you will catch.
YOU NEVER KNOW WHAT YOU WILL
CATCH.
• Amateur Radio in its purest form is about radio and
radio propagation.
• Many of us entered into this hobby because of our
fascination with radio and radio propagation.
• The unpredictable nature of radio propagation keeps
our interest. You never stop learning.
• This unpredictable nature is like fishing. You never
know what you will catch.
• If every time you threw in your line, you caught a big
fish, it wouldn’t be much fun would it?
WSJT SOFTWARE by K1JT
• WSJT is the name of a computer program. The name
stands for “Weak Signal communications by K1JT.”
• WSJT has four modes of operation intended for VHF,
UHF or microwave communication.
• K1JT provides this program for free!
• Source code is also available for free!
• It is available on the web at: K1JT’s WSJT page:
http://pulsar.princeton.edu/~joe/K1JT/
JOE TAYLOR K1JT
• Joe Taylor, K1JT, the author of WSJT, obviously
shares a fascination with radio as do most hams.
• K1JT is a Nobel prize winning radio astronomer, well
qualified to write software like WSJT.
• K1JT’s knowledge of detecting extremely weak radio
signals is apparent in the function and performance
of WSJT.
• Joe wrote WSJT and he operates WSJT often. He is
an active VHF operator on WSJT and the other VHF
and above weak signal modes.
WSJT’s FOUR MODES
• FSK441: VHF communication via meteor scatter using
reflections from very small meteors. A meteor shower is not
needed, it works 24/7.
• JT6M: The same purpose as FSK441 but optimized for
6 meters. It is slower in speed but 10 dB more sensitive.
• JT65: Communication with very weak signals of roughly
constant strength. Troposcatter and Earth-Moon-Earth (EME)
communications, VHF, UHF and SHF.
• EME Echo: Tests station performance by detecting and
measuring EME echoes. Noise measurements and path
calculations.
FSK441
• Designed for VHF high speed communication using
very brief “pings” of signals reflected from very small
meteors, between the size of dust and a grain of sand.
• These meteors ionize the E layer at about 100 km, and
support communication from 400 to 1500 mi.
• These small meteors are present 365 days a year and
QSOs may be made 24/7. A shower is not required.
• A good 100 ms reflection will decode a full set of calls!
A 20ms “ping” will decode 3 characters.
JT6M
• Also for high speed meteor scatter, but
especially optimized for the 6-meter band.
• Meteor reflections on 6 meters are stronger
and longer.
• JT6M is slower, taking advantage of the
longer reflections while providing 10 dB
better sensitivity than FSK441. Shannon's
Theorem.
• It is not appropriate for use above 6 meters,
FSK441 is better on 144, 222 or 432 MHz.
JT65
• For extremely weak but slowly varying signals such
as those found on troposcatter and EME paths.
• JT65 can provide a 15 dB improvement over a
skilled EME operator on CW!
• A 15 dB improvement is like having a array of least
sixteen antennas instead of one, or a kW instead of
30 watts!
• It makes EME possible with a small station and for
operators that are not proficient at CW.
• WSJT does NOT do everything for you! EME is still a
challenge.
EME ECHO
• EME echo testing without this software is difficult
using only your ears.
• WSJT provides a qualitative way to measure your
station performance.
• In the EME echo mode WSJT will measure noise from
the Sun and other sources.
• It is easier than other ways of performing noise
measurements.
• This testing ability allows a weak signal operator to
establish a baseline for station performance and
evaluate changes.
OK, LET’S GO FISHING
• You probably already have the radio and the
computer. The expensive part.
• You need more than just the tackle box.
• You can’t go fishing without a pole! You will
need an antenna.
WSJT FSK441 MODE
• “pings”
heard at
K1UHF
• Transmit
CQ
• Transmit
Multi Tone
73s
• Transmit
Single Tone
73s
A SMALL POND:
METEOR SCATTER
• 2 meter meteor scatter contacts from K1UHF, FN31fh.
A FISHING POLE TO CATCH
METEORS?
• You don’t need much aluminum.
• With a loop antenna or 3 element beam and only 25
watts you can work bigger stations.
• 1000 mile FSK441 signals have been heard with a
vertical! From Connecticut, K1UHF has worked five
stations West of the Mississippi that had less than 25
watts and 3 element beams or smaller.
• Bigger may not be better. Meteors sweep across the
sky. An antenna with a tight horizontal pattern may not
always help.
WHAT OTHER FISHING GEAR?
• A 6 or 2 meter multi-mode (USB) radio.
• A computer with Windows 98 or higher and a Pentium
75 or better.
• A sound card interface, such as a RIGblaster.
Microphones in front of speakers will work for
starters.
• A free copy of WSJT.
• Accurate frequency calibration, + - 200 Hz.
• Accurate computer clock. SNTP, Dimension 4.
FISHING TECHNIQUE
• You can make contacts 24/7 with FSK441 MS
• There are almost always enough good meteors to
make a contact during a 1/2 hr sked.
• Late evening to midday is better.
• WSJT doesn’t work well during a shower, pick up you
microphone and switch to SSB.
• It is unlikely you are going to tune around and find
someone calling CQ on MS.
FISHING TECHNIQUE
• Most contacts are made with skeds.
• Random contacts can be made with WJST during a
contest or minor shower.
• CQs are done on the random calling frequencies of
50.270 or 144.140 MHz.
• Use W0UK’s Ping Jockeys web page to make a sked
or to monitor activity:
http://www.pingjockey.net/cgi-bin/pingtalk
PING JOCKEYS
FISHING TECHNIQUE
• Set WSJT up with you call, 6 digit grid square and for
PTT activation.
• Tune in a clear frequency and click “monitor” wait a
few seconds then hit “stop” to measure and set the
WSJT receive audio level.
• Go to the Ping Jockeys web page find skeds in
progress to “monitor” (receive).
• Set your USB receiver dial reading to the sked
frequency and watch the “DF”.
• You will hear the pings. Wait a bit and WSJT will
decode the signal.
YOUR FIRST CATCH
• To monitor other QSO’s be sure to listen to a station
500 to 1000 miles away.
• Type his call in to the “To radio:” box and click
“Lookup”, WSJT will show your beam heading and
the distance.
• You found the fish now catch one, make a sked.
• But first: Read Ping Jockey’s “You must read this”,
also read the WSJT manual and help files.
• To make your first sked find a big station, type that
you want your first sked on Ping Jockeys.
YOUR FIRST CATCH
• Coordinate the time, frequency, who transmits first
and if A B or C tones will be used. For example,
post: “W8WN 144.128, 0230 Z, your 1st A”. The
Westerly station is usually first in North America.
• Type in the other stations call, aim your antenna.
Select “TX First” or not and “ST Msg” or not.
• Hit a tune button and check for transmit audio
reaching the radio at the proper drive level.
• Turn “Auto” ON to start WSJT’s transmit/receive
sequencing.
YOUR FIRST CATCH
• Sit back and listen for a meteor ping.
• If you hear a good meteor WSJT should decode on
the next over.
• If you get good copy during a sequence MAKE SURE
that you change your transmit message to the next
APPROPRIATE message.
• BTW you may change the message during transmit.
ENJOY YOUR MEAL
• Exchange call signs, signal reports, rogers and 73’s
and you have made your first valid QSO.
• Log it! You’re a Ping Jockey!
• Congratulations: you never know what you will catch.
• You are probably hooked.
• You could spend the next few years working all the
stations within MS range but how about some more
distant contacts?
CATCH THE BIG ONE
• JT65 EME will take a bigger fishing pole and better
tackle (more power) than FSK441 MS.
• EME is the ultimate DX, don’t think it is easy.
• EME requires that you station performs perfectly.
• JT65 EME contacts don’t need anything near as much
as a CW station but you do need a good setup.
• JT65 EME will be a rewarding accomplishment.
• It is possible to work another 2 meter station if you
both have only a single long yagi and 100 watts.
WSJT JT65
• AH6LE on
JT44
• Calling
AH6LE
• Sending
rogers
CATCH THE BIG ONE
• Put a good GaAs FET preamp ahead of your receiver.
• Use low loss feed line, preferably after the preamp.
• You may wish to use a simple antenna setup near the
ground. Manual azimuth and elevation rotation by
bore sighting the Moon is cheap and effective.
• If you already have a large beam up high with only
an azimuth rotor you will be limited to operating
near Moonrise or Moonset.
• When you think you have everything set up properly
use the WSJT Echo Mode and check your echoes.
CATCH THE BIG ONE
• You may not find your own echoes with WSJT but you
should be able work the larger stations.
• Go to the Ping Jockeys JT65 page and monitor some
skeds, pick the big stations first.
• Keep your antenna pointed at the Moon, it moves.
• Make sure you time and frequency are calibrated as
well as you can.
• If you are decoding signals with success you should
be ready to try a sked.
CATCH THE BIG ONE
• Make a sked on the Ping Jockey’s JT65 EME page.
• Again get all the details correct between both
stations.
• If you both transmit and receive during the same
sequence it does not work well. “BTDT”
• The station that has Moonrise first transmits first,
opposite MS.
• You may have a one way path, the craters on the
Moon do funny things. Actually Faraday rotation.
• A full Moon is always better, there is more reflecting
surface, right?
CATCH THE BIG ONE
• Got you didn’t I! It is actually worse, more Sun noise.
• It is better to operate on an “EME weekend” when the
Moon is at perigee and degradation is low.
• JT65 has message averaging. It lets you decide
whether to “Include” “Exclude” or “Fold” messages.
• The JT65 message averaging can make a big
difference if used properly.
• Once you have made you first contact, you will think it
was worth it: 500,000 mile DX.
• With a small station, QSO’s are difficult, but once you
get the bug you will put up that big array.
WSJT RELATED WEB LINKS
•
•
•
•
•
•
K1JT’s WSJT page:
http://pulsar.princeton.edu/~joe/K1JT/
WOUK’s Ping Jockeys real time chat page:
http://www.pingjockey.net/cgi-bin/pingtalk
WA5UFH’s meteor scatter etiquette page:
http://www.qsl.net/wa5ufh/DOS/Etiquette.htm
W8WN’s meteor scatter page:
http://www.qsl.net/w8wn/hscw/papers/hscw-sop.html
WB5APD’s JT44 EME tips page:
http://www.qsl.net/wb5apd/jt44-eme-tips.html
WEST MOUNTAIN RADIO, RIGblaster sound card interfaces home page:
http://www.westmountainradio.com