Questions regarding APF implementation

  • 3
  • Question
  • Updated 5 years ago
  • Answered
I see there have been several instances already of people having audio issues due to enabling APF then switching to SSB where apparently the APF is still active and causing confusion as to why the audio "is not working correctly".

Is there even a reason for APF to be active in a that's not in CW mode?  Why would SmartSDR bypass APF if not appropriate?


Today APF is a radio-wide CW Transmitter Control setting affecting all slices.  Should it maybe be on a slice-by-slice basis or at least bypassed when not appropriate for the mode?


 - Bob, W1RE

Photo of W1RE

W1RE

  • 95 Posts
  • 18 Reply Likes

Posted 5 years ago

  • 3
Photo of Steve - N5AC

Steve - N5AC, VP Engineering / CTO

  • 1031 Posts
  • 1002 Reply Likes
Official Response
There were a lot of requests for APF and we had a very simple method for adding it using the codec in the radio.  All audio output from multiple channels and modes is demodulated, and then combined according to the volume and fade settings in the radio.  The final composite audio is sent to the codec for output to the speakers and/or headphones.  So we implemented this first pass of APF in the codec, but the draw-back is that it affects all output from every mode.  We rationalized that the serious CW guy using this won't have a SSB receiver on at the same time.  But the better implementation is to perform the work before the codec and only on CW slices.  We didn't have time to switch implementations for v1.1, and felt like it was better to get this implementation in your hands with the caveats rather than pull the feature entirely.  We expect the user controls to be the same so there was no danger in getting folks trained on one thing only to switch to another.