[hpsdr] AF gain / RF gain what is the difference?

[David Woodhead]

Can someone explain to me how the AF and RF gain controls are
implemented in Power SDR? How does one optimize the adjustment of each?

I do understand what these controls do in a classical receiver but not
in the SDR where they are both implemented in the digital domain. 

Ultimately I'd like to explain the strange noise I hear with the RF and
AF gain at ~50% with Janus/SDR1000 that I do not hear with the
D44/SDR1000.

Thanks!

David
KM5TZ