[hpsdr] Proposal for a 'low-end' RX/TX board for HPSDR

[Ahti Aintila]

On 21/07/06, Ray Anderson <ray.anderson at xilinx.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> >Hi Ray,
>
> >Sounds good.
>
> >I have a circuit for a proposed QSD-like design (actually a sampling
> >integrator) using some simple components.  If you are interested I can
> >email you a schematic.  I think Bob N4HY has been working on a QSD
> >also.
>
> >73 de Phil N8VB
>
> Phil-
>
> Sure, send it on over. I've been looking at several QSD based designs
> trying to pick the best features from the mix. I'd like to see what you
> are thinking of.
>
> 73 de Ray       WB6TPU
>

Hi Ray, Phil_C, Phil_H, Bob, et al,

Bob's idea of a potential QSD (July 07, 2006) with fast analog
switches is very interesting. There might be a small error, though.
Pin 2 of U5 obviously should go to Pin 1 of U2?
<svn://206.216.146.154/svn/repos_sdr_hpsdr/trunk/N4HY/Horton/QSD.pdf>.

Using those components I figured out another configuration. Instead of
using 90° narrow sampling pulses, I plan to use 180° wide pulses in
quadrature. Transformer coupled dual line receivers split the I and Q
signals from the DDS to pair of opposite pulses with minimal skew and
timing errors.

See this and tell me what I possibly missed:
<http://kotisivu.dnainternet.net/ahti/sdr-1000/newmix2.pdf>

Ahti OH2RZ

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