[Elecraft] K3 vs. HPSDR Mercury receiver

[David Woolley (E.L)]

Dave G4AON wrote:
> Members of the RSGB may wish to sneak a preview of the December
> RadCom article on SDR where the authors compare a K3 with a HPSDR
> Mercury receiver and explain why the SDR sounds better than the K3
> (noise through a crystal filter causing phase changes).

I've read the article and it is really comparing two types of SDR 
receiver, rather than SDR and analogue.

The type they are claiming the benefit for is one in which digitisation 
is performed at signal frequency.  The other type is the design used by 
both SoftRock and K3, in which the signal is first mixed down before 
being digitised.

The sort of noise they are talking about is impulsive noise, 
specifically atmospherics due to global lightening.  A filter with 
non-constant group delay will turn these from clicks to chirps.

It is possible the SoftRock will do better in this respect, because 
typical sound cards have a constant group delay anti-aliasing filter.
> 
> http://www.rsgb.org/membersonly/radcom/techfeatures/sdr_1208.pdf
> 
> </div>


-- 
David Woolley
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