On Jun 26, 3:32*am, Paul Keinanen wrote:
Excuse my ignorance, but why on earth do you do some crude analog
filtering and then continue with digital filtering, in which you have
much more alternatives ?

To undersample the signal it must be bandwidth limited which means
some
type of analog filtering. As long as filtering is necessary, it might
as well be a narrow as the widest signal of interest and as sharp as
possible so long as it's convenient and doesn't distort the signal too
much.

why would anyone use the receiver CW filters

Probably a bit narrower than what I had in mind … I'm currently
looking
at 500 KHz wide SAW filters.