On Fri, 2006-04-07 at 15:33 -0700, John Nason / NA9U wrote:
> The Weaver method is sometimes called the third method
> of generating SSB. Phasing and filtering being the
> other two. In a weaver you down shift the baseband
> signal so that the center is at DC and then put the
> signal through low pass filters which are easier to
> build digitally. The system then upshifts the signals
> back to IF and adds/subtracts them to get IF output.
>
> Weaver wrote a paper on this in 1956. The appeal of
> the Weaver is the low pass filters in lieu of bandpass
> filters which are used is a normal phased system.
>
> Smith shows one in block diagram form in his book
> "Digital Signal Processing" on page 5-10.
>
> 73,
> John NA9U
>
I believe Weaver's original article was in the December 1956 issue of
the proceedings of the IRE that was dedicated to SSB. Most everything
developed since has had basis from that tome. I have it in my library
somewhere.
One of the faults of the Weaver method is that faulty phasing and faulty
filters lead to fold over products (inverted audio) in the pass band. I
think it was claimed that the trash didn't show up in the opposite
sideband or nearby like the typical straight phasing rig or filter
blowby in the filter rig.
I've not tried to make the Weaver method work, I have tried phasing and
filter and I like filter better than phasing but I'm willing to try
phasing with DSP one of these days.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|