[hpsdr] SDX Design, HORTON, CASMIR, and GIBRALTAR

[Lyle Johnson]

> Looking some more at the P3E SDX block diagram.
> Are flight test L & U band receivers are existing and are
> being exhibited at Dayton? Or is the hardware still at
> prototyping stage?

Prototyping, proof of concept is my understanding.  Demonstrates the 
functionality.

> Is the design for the receivers available? It might give HORTON design a boost. 

I suspect the design will be available.  Note that the design will be 
optimized for what a spacecraft must contend with looking at a noisy 
earth full of radar, which may be quite different than what a 
terrestrial station contends with...or not.

> The reason behind my asing is this quote fromm the AMSAT-NA website ...
> "A working Software Defined Transponder(SDX) on 2M and 70cm,
> like the one to be used on our EAGLE satellite will be on display."

Yes, a functional prototype should be on display.

> What if GIBRALTAR placed a 10MHz signal onto ATLAS, and then
> MERCURY, HORTON, and CASMIR could use it as a reference signal
> as a basis for whatever local osc frequency was required. For
> Bob's phasing idea, there could be a separate LO bus shared
> between multiple CASMIRs. I worry that we might be introducing
> too much noise into the system if we try to ship a VHF/UHF LO
> onto ATLAS.

10 MHz at 3.3V logic levels ought to be fine.  If you need to pipe LO 
signals, I'd suggest using coax, not ATLAS.

73,

Lyle KK7P


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