David,
If you have not read it, the December 2008 issue of QST contains another
review of the Perseus.
Although I own a Perseus, which I bought for use as a piece of test
equipment, I do not own a K3 thus cannot compare their 'sound'. I can say
though that I have never been comfortable with the 'sound' produced by most
commercial amateur and military receivers which use DSP, but I do find that
the 'sound' produced by Perseus, especially when a CW, SSB or AM signal is
close to the ambient noise floor, is certainly not hard on the ears - it is
quite mellow. Both its NB and NR work well.
73,
Geoff
GM4ESD
David Woolley (E.L) wrote:
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
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--
David Woolley
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