Fldigi used to work fine, but recent updates may have caused me to drop off the face of the (radio) earth. What it seems to be doing — and I don’t find this at all plausible — is causing interference with its own audio stream when its window has focus, but receiving perfectly when the program window is hidden. As Fldigi is a highly interactive program, this is not much use. Here’s an audio sample showing what I mean: fldigi-psk14070-VA3PID-201206092107z. It’s about 45 seconds long, a sample of the 20m PSK31 band this afternoon, and comprises:
- 0-15 seconds: fldigi’s window is in focus. None of the traces in the waterfall resolve to meaningful text.
- 15-30 seconds: I changed focus to another program. The waterfall traces snap into focus; QSOs become readable. The conversation at 2383 Hz goes from line noise to a very clear “… 73 73 Jim and thanks for ans[w]ering the cq …”
- 30-45 seconds: fldigi’s window is back in focus, and all decoding is cut off.
I’m running fldigi 3.21.43-1~kamal~precise from the Ubuntu Amateur Radio Software Updates repo. Hardware is a Thinkpad R51 (a bit old), latest Ubuntu 12.04 LTS, a FT-857D into a Signalink USB, and the audio’s being handled by PortAudio. I’m stumped!
Update: It was a volume thing. Linux had decided that I didn’t need my main system volume above 10%, so fldigi was picking up noise only.