[hpsdr] Gibraltar fanning out clock and 1pps to HORTON/CASMIR/MERCURY/..

[Eric Blossom]

On Mon, Jul 10, 2006 at 03:41:52PM +0200, Achim Vollhardt wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Dear HPSDR group,
> I would like to remind people about the coherent system approach Bob and
> others mentioned some while ago:
> 
> IF we manage to derive all signal path clocks from a single source
> (let's assume a 10 MHz GIBRALTAR for now), this system will be able to
> PRECISELY time any recorded signal to the sub-100 ns level!

Coherent processing will be very useful.  However, sub-100 ns is way
too sloppy if you're dealing with 100 MHz sampling clocks.  That could
be 10 samples!  Accounting for aperture jitter at those rates, the
specs get even tighter.

It seems to me that for any serious coherent processing, clock
distribution is *not* going to happen across the ATLAS bus, but rather
through equal length coax or LVDS/LVPECL in some kind of star configuration.

If I'm wrong, please set me straight, and explain to me how you plan
on handling a system with say 4 MERCURY's, or 4 HORTONs for that matter.

Eric, K7GNU

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