> I think Dave and Adrian's conclusion is correct. My take: for a SDR, if no
> signal was converted during the A to D stage, there will be no signal to
> "dig out" during the D to A stage. No amount of signal processing or noise
> reduction will help since there is nothing there. Nothing is buried in the
> noise floor.
>
The A/D will convert any signal that is there. Consider that FT8 can "dig
out" signals well below the minimum signal that can be detected by ear on
CW. I suppose one could adjust the RX gain such that weak signals are
below the MDS, but that is not an SDR issue.
It is interesting that the CW speaker works well for these guys. Having
tried a couple electronic audio filters, I found that the filter ringing
made them not too useful for weak signals. I wonder how these mechanical
filters sound in comparison.
Chuck KM3V
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|