Using JT4 for QSO' s (together with WSPR)

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f6irf's picture
Last seen: 8 years 3 months ago
Joined: 2008/04/18 - 12:24
Using JT4 for QSO' s (together with WSPR)

Although the number of requests for WSPR QSO's has decreased, it maybe friendly to have a QSO fm time to time, whith the guys you see beaconning for hours, days, weeks or monthes...

for those QSO's I would like to suggest to use JT4A 'srather than WSPR.
The decoding limit of JT4A is around -25, thus 3dB below WSPR, but it is better than the WSJT-WSPR decoder anyway... taking into account that transmitting period are roughly 1/3 of WSPR period, you may increase your power by 3dB and still have less stress on your transceiver PA.

Compared with WSPR and JT65 the JT4 mode offer the following advantages:
- it is a narrow band mode compared to JT65A, just a bit wider than WSPR
- it uses the same message structure and same 40s period durations as JT65
- periods are easy to identify (unlike WSPR) even minutes 00, 02, etc are first period, odd minutes 01, 03, etc are second
- Unlike WSPR-QSO mode there is no compromise on callsigns transmission (CALL between brackets), so anybody can monitor and identify both stations, even if he missed the beginning of the QSO...
- decoding is fast; so you have near to 20s to get ur message ready for the next period
- and of course a JT4 QSO take half the time of a WSPR QSO

Last but not least
- both programs can run in // using the same TRX frequency - the audio frequency of JT4 is 1270Hz so it won't interfer with the WSPR band segment (1400 to 1600Hz)

From now and until further notice I will run JT4, when running WSPR
- I will reply to CQ's if I am at the station
- If I am not at the station, you'll be spotted on w6cqz page so you have better chances to find a correspondant replying to your CQ

Just a few tips about the auto-spotter:
- Make sure I am not transmitting in WSPR; in this case of course I won't hear anything...
- Freq tolerance is set to +/-100hz around 1270hz (0 DF), so call within those limits if you want to be spotted...

If you hear a CQ
- put WSPR on RX - and select the opposite period of the CQ'er in WSJT
- to get HF standard messages auto-generated (with numerical signal reports), double right click on the call (and it will switch AUTO-ON)
- just after message decoding tick the box in front of the message to be sent next
- That's it ! (if for some reason you did not decode a message, repeat the same message until you get something decoded)

A typical QSO should look like this:

0800 CQ LA3JJ JO59
0801 LA3JJ F6IRF
0802 F6IRF LA3JJ -10
0803 LA3JJ F6IRF R-12
0804 F6IRF LA3JJ RRR (Then the QSO is complete)
0805 TNX JON 73 or LA3JJ F6IRF 73 (something like this is recommended as it confirms that you have received the RRR)

you may add msc infos like (13 characters max)
0806 5W VERT 73
0807 10W 2EL BYE (OR PSE QSY 12M / SUNNY 32C / or whatever you like...)

Please refer to the WSJT manual for further details