[hpsdr] Excalibur/PowerSDR/HPSDR behavior questions

[Graham / KE9H]

Dan:

John is correct. 

The current and recent versions of both Mercury and Penelope
will free run in the absence of a reference clock.  There is no 
indication or alarm
if they are not locked.  Even when free-running they seem to stay within 
about 30
to 100 Hz of the indicated frequency.  If a 10 MHz signal is present on 
Atlas bus line
C16, they will lock to it, whether it comes from Mercury, Penny, or an 
external
source like Excalibur. 

Just don't have multiple 10 MHz sources feeding the bus simultaneously.  
I don't
think it will break anything, but it things will behave strangely.

Very early versions of the Mercury and Penelope software would lock up and
stop operation in the absence of a reference.

--- Graham / KE9H

==

John Ackermann N8UR wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Dan, I *think* that Merc and Penny use the 10 MHz signal to lock their 
> on-board 122.88 MHz oscillator.  If the 10 MHz goes away, the 122.88 
> TCXO keeps free running, but the frequency may jump noticeably and 
> Merc and Penny will no longer be locked together in frequency.
>
> John
> -----
>
> Dan Quigley said the following on 11/17/2009 08:36 PM:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>>
>> ------------------------------------------------------------------------
>>
>> Happy to report that Excalibur is working great here in my shack.  A 
>> big thank you to Graham and the rest of that team.   I have a couple 
>> questions about how the PowerSDR/HPSDR system handles the 10Mhz 
>> reference clock.
>>
>>  
>>
>> What happens if Excalibur stops broadcasting its 10Mhz reference 
>> clock onto the Atlas bus?   I didn’t see an indication on PowerSDR or 
>> notice that Mercury stopped receiving.   Is there a way in software 
>> to detect and indicate what card is supplying the clock?
>>
>>  
>>
>> Best 73’s
>>
>> Dan (N7HQ)
>>
>>


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