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

[Achim Vollhardt]

Dear Eric and Bob,
I am not an expert on coherent techniques, but my understanding is, that
you need stbale and reproducible phase relations, not necessarily
phase_difference=zero.

Also to Bob: I was guessing my sub-100 ns was a little bit
conservative.. that's what my limited experience taught me up to now..
Anything else about Interferometry, I'll leave up to somebody with more
experience, but I had the feeling to point out the importance of
desiging HPSDR with the punch to go coherent, if needed.


This looks more exiting with every minute.. right now, literally :)

73s Achim, DH2VA


Eric Blossom wrote:
> 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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    Dr. Achim Vollhardt
    Universitaet Zuerich
    Physik Institut, 36H24
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