Extra decoders are set in the Modem config tab in the Add Rx n pairs
box.
These are not needed on FM. On SSB tuning has to be within about
30Hz for packets to decode successfully. This amounts to a TX to RX
accuracy of around 2 parts per million on 20 Meters. Modern rigs are
usually that stable, but do not always have that accuracy. So QtSM
can add extra decoders tuned +- 30 Hz from the nominal. I find two
pairs (a total of 5 decodes) is usually enough for normal HF
operation. Each extra pair adds to the cpu load so if you are
running several modems on a relatively slow platform like a Pi 3 you
may need to check that you aren't overloading the cpu.
QtSM reports the success of each decode in the form [--+++]. This
shows that the top 3 decodes were successful, suggesting the station
was around 30 Hz high. If all stations appear either low or high it
may mean you are a bit off frequency. If you see stations that are
always? on the edge (eg [----+] than maybe you need more decodes (or
to persuade the other station to move a bit!)
73,
John
On 18/05/2023 23:28, Matthew 2E0SIP
wrote:
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Hi Red,
Thanks for the debugging tips.
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Make sure you¡¯re only running 1 extra pair of decoders per
port on QtSoundModem if running on SSB
I'm not sure where this is configured? I've not enabled any.
Make sure IL2P isn¡¯t enabled as well as FX25 on a single
port.
IL2P is disabled on both sides (QTSM and the NinoTNC)
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Try fiddling with the extending the TXDelay in normal AX25
mode.
I set it to 500ms to rule out any issues and it didn't help.?
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I've attached the WAVs. Both are the string "Hello" sent 3
times.
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Thanks
Matthew
2E0SIP
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