AGC ramps up with no audio input

[formtapez]

Hi,
when having absolutely ZERO audio input, FLDIGIs AGC ramps up and opens the squelch, resulting in RTTY decoding garbage.

I´m using virtual audio cable between SDR-Console and FLDIGI to decode RTTY. When SDR-Console´s squelch is closed, we have real ZERO audio input to FLDIGI. After 30 sec to 1 minute FLDIGI is raising the audio level up and up (i think its an internal AGC) and the squelch opens. Then RTTY is decoding garbage characters.

As a workaround i inject very silent noise to the virtual audio cable, so FLDIGI´s AGC stays low.