[Premium-Rx] SDR as a means of decoding low-frequency IF output of premium receivers

[F3WT]

Hi gents,

Recently I posted a question on  the Siemens E311 series. Although not  
satisfying 
admission /criteriae/ for this Group, I was told, I got 2 nice replies 
though.
Meanwhile I got a E311b1b. All I can say is it is very very quite ( very 
less noisy ) compared with my TS590 even with its  digital NR1 or 2 on .

Nevertheless: This receiver has an IF ouput jack (of 30kHz). Rather than 
using an SDR with Tayloe QAD detector, I am looking now
for a direct input of that signal into an A/D converter and 
processing/decoding most modes ( to be honest, CW in my case with 
digital filtering).

Most modern receiver do this on their last - and still low - IF ( as 
does a TS590 for instance).

While one finds very many references about Tayloe based SDRs , it seems 
to me few litterature describes  practical homebrew implementation of
the latter case ( direct digital processing ).
Does anybody have references to this.
I would be very gratefull for any hint.
It seems to me  also since  this would apply to those many premium 
receiver with IF outputs on their back, there should be quite a few  cases 
where external direct digital IF processing  has been done and published.

Thanks in advance.

Pierre, F3WT