Hello! In order to lower QRM, increase QSO rate and speed up user education, there are several proposals, all efectivelly blocking QRM transmission in different conditions.
1. one spare FT8 bit is used as KN bit (Do not transmit unless invited) 2. When there are several responses to CQ, implement Aloha principle (repeated retransmissions are randomly blocked) 3. Do not transmit if time left is too short for good decode. For all three cases where TX is automatically disabled, normally red "Enable TX" shall go yellow for duration of blocked TX period. There should be manual override with keyboard, in case operator knows he has to transmit. KN bit (one of spare bits): -------------------------------- For a century KN on the end of CW transmission means "only invited station shall transmit, others stand by). In FT8, quite often we see unwanted transmissions. People call in the middle of the QSO etc, probably overlooking when to press "stop TX". With FT8 HF dominance, it makes sense to use one of three spare bits to indicate KN. WSJTX-X shall add KN bit on all frames but CQ/QRZ (when everyone is invited) and final 73 (where KN omitting is effectively meaning CQ/QRZ). When KN is received, station shall check: - if my call is in the frame, I can transmit. - if I am in the QSO, and about to send final TX lines, I can transmit (messgae without calls, like "TU 73 LOTW") - if originator of KN bit is not in my qso, ignore KN, I can transmit (some other QSO) but: do not send to originator if I am not in the QSO. This shall work even if TX/RX tones are not same, there is no need to call DX in the middle of QSO. Wait till she is listening for another QSO partner. Usage of KN bit is not needed so much in other modes, so it is justified to be "FT8 specific". By checking both calls, we can avoid KN bit misuse to get faster response (sending fake KN message to stop legitimate callers). This is to be considered for wsjtx-1.90, probably. But in some time, most of clients would resoect KN bit (even on CW some stations do not) Aloha ------------- Sometimes even S52D calling CQ receives several answers, similar strength, so no response is decoded. All calling stations just repeat calling. Classic action is: stop calling CQ and wait till somebody stops calling, until one station is decoded. Or send "PSE SPLIT". This can be done automatically: when answering CQ, transmit twice. On third call, use 50% probability to transmit or not (so, it makes it more likely for one answer to get decoded). On fourth and next repetitions, use 33% probability to transmit. Of course, regardless of frequency: there is often congestion on other tones as well. Combined with split, this can help even rare DX to make more QSOs. This is not hard to implement, but can help a lot. Maybe too late for 1.80. Short transmissions ------------------- Very often, I am too late to select next QSO partner, so I start transmitting late. Thus, I generate only QRM, as my transmission can not be decoded. SO, no FT8 transmission starts more then 5 seconds after period starts. This can go to 1.80, it is easy to implement and test. It is mode specific, and again, mostly needed on FT8. Best regards, mni DX, 73 es GL Iztok, S52D s52d FT8 status: 165 DXCC, over 5000 QSOs, K1JT on three bands [http://psn.sdn.si/ts/katalog_jesen_2017_email_podpis.png] <http://www.telekom.si/Documents/PDF%20Prodajni%20katalogi/mali_prodajni_katalog_jesen_2017.pdf?utm_source=mail_podpis> Pravni pogoji / Legal disclaimer Telekom Slovenije, d.d., Ljubljana <http://www.telekom.si/disclaimer> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
