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.

• “pings” heard at K1UHF • Transmit CQ • Transmit Multi Tone 73s • Transmit Single Tone 73s

WSJT FSK441 MODE

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.

• • • AH6LE on JT44 Calling AH6LE Sending rogers

WSJT JT65

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