WSJT ("Weak Signal Communication, by K1JT") offers specific digital protocols optimized for meteor scatter, ionospheric scatter, and EME (moonbounce) at VHF/UHF, as well as HF skywave propagation. The program can decode fraction-of-a-second signals reflected from ionized meteor trails and steady signals 10 dB below the audible threshold.
The WSJT software package (incorporating FSK441, JT6M, JT65 and JT2/JT4/WSPR experimental modes) can be downloaded from Joe Taylor K1JT's website.
December 2001 QST Article on WSJT by Joe Taylor K1JT
Meteorscatter Documentation:
Art of Copying MS Pings
The use of WJST (FSK441) in 144 MHz band
A Typical Meteor Scatter QSO Experience
Seven Necessary Steps
EME Documentation
Digital EME Communication
TIME SYNCHRONISATION
All the WSJT modes work on specific timed cycles, and as such it is critical that the PC's time is synchronised very accurately (to within less than a second). You can not successfully have a WSJT QSO without a close synchronization of your local computer's time value to UTC. Period. End of discussion. If you have internet access there is NO EXCUSE for not having a properly synchronized clock.The most popular solution for accurate time calibration is Thinking Man Software's Dimension 4. This is free software, and can be configured to calibrate your PC to an Atomic Time Server at regular intervals.
If you do not have internet access your only option is to try to maintain a manual sync by some broadcast time service. If you can get (and maintain) accuracy within +/- 1 second of UTC you should be able to work other stations. The closer to perfect the better.
Also. Do not assume your PC's clock is stable. Many have highly inaccurate clocks that gain/lose time at a substantial rate.
JT65 ON HF
After many years of VHF-only use, experimentation with JT65 on the HF bands proved that this mode was eminently suitable for weak-signal work on the sub-30MHz bands. A number of useful guides for use of JT65 soon appeared, most notably K3UK's Bozo Guide to HF JT65A and The BARTG guide to starting with JT65A on the HF bands
Despite these guides making the use of JT65 easier, many users longed for a more straightforward solution. This was addressed by Joe Large W6CQZ and his excellent JT65-HF software. JT65-HF is based on the code from the WSJT Project, but utilises a number of unique elements that make it uniquely suitable to HF operation.
W6CQZ also maintains the HF JT65A Logger and a Google Group. Prospective users of JT65-HF are encouraged to join this Google Group.
Some considerations for using JT65 on HF:
JT65 is indeed an FSK mode in that it transmits distinct single tones from a tone set of 65 values. But.. JT65 is NOT TRANSMITTED using FSK. It uses AFSK and this is a critical distinction. Avoid ALC action if possible with an AFSK signal. Much like any other audio input to an SSB transmitter JT65 can generate a poor signal if over driven. JT65 is a weak signal mode. Its primary purpose is to facilitate EME (Earth->Moon->Earth) communications. For use on HF you need to re-think your power levels. Often a few milliwatts will do amazing things. Some situations call for much higher power levels, but in day to day HF usage, 10 to 20 watts is probably enough, if not too much.