Thanks Jan
It doesn't show up here as under/overruns in the status page - but I'm pretty sure that the resampling is needed to match the microphone incoming stream to the outbound IQ stream as that channel is usually the cheapest interface. Sometimes switching microphone interface devices changes the clicking behavior here - presumably because the two cards have slightly different data rates
I find the clicks far more noticeable in NBFM mode and I too got reports of clicking from local repeater users. At first I ignored them and tried to deal with them by keeping the microphone input high as I thought it was PL tone leakage, but later when I investigated more closely I could clearly see and hear them in the transmitted signal. I think people don't notice them as much in SSB due to normal atmospheric noises.
They are often bad on FT8, but I think that depends on vagaries of Pulse Audio (which I see has been completely removed by the Raspbian developers in Bookworm!), Again, however digital users have no way to report them back to me even if they could tell they came from my signal and not those of the rest of the pack. When they're present they're quite audible and measurable in a local receiver.
On CW, the sine wave is generated locally and is usually clean and in sync - however sometimes if another mode has been in use the clicks appear for a little while during the first key down until things get settled.
I guess ideally, the incoming streams would be adjusted rather than the outbound IQ since there's certainly an LPF early in input streams. I can see why it's not been done that way, however as there are a lot of inputs of different sorts that would need to be adjusted and kept track of. It might be very messy....
I still haven't got back to work on using my codec clock synthesizer to resync the output stream as I'm in the midst of chaos from new computers and a roof replacement going on all around me, but I'll try to get back to it next week. It won't really fix quisk, but might provide a useful data point for comparison and it would solve my immediate problem.
M
