[eagle] Re: Eagle 10 MHz Clock

Jim Sanford wb4gcs at amsat.org
Tue Apr 10 17:52:52 PDT 2007


Alan:
This requirement came up in the peer review, and was imposed on the design.

It needs to become a system requirement.  I've separately requested 
draft of such a list of requirements.

Thanks & 73,
Jim


Alan Bloom wrote:

>Is the 10 MHz reference a possible single point of failure?  Has it been
>made a requirement that all subsystems fail gracefully if the 10 MHz
>reference disappears?
>
>Alan
>N1AL at CDS1.NET
>
>On Mon, 2007-04-09 at 20:06, Jim Sanford wrote:
>  
>
>>Bill et al:
>>The requirement for the 10MHz reference descends from the July 2004 
>>meeting in Orlando.  As far as I know, it was never thoroughly 
>>justified, it was stated and made sense at the time.  Still does, to me, 
>>tho I could be convinced on a case basis that we might not need it.
>>
>>73,
>>jim
>>wb4gcs at amsat.org
>>
>>
>>Bill Ress wrote:
>>
>>    
>>
>>>Some very good dialog has been taking place, lead by Juan Rivera as he 
>>>heads up the prototype U Receiver build and test project.
>>>
>>>Several very important questions have been raised but I'd like to 
>>>address just one with this post.
>>>
>>>I've volunteered to design and build the S2 Receiver and the C 
>>>Transmitter and support microwave component efforts on the phased array 
>>>for each. I am finishing efforts on a "prototype" single channel 
>>>(assuming there might be several) S2 downconverter.
>>>
>>>I fully recognize than "many" system design parameters have not yet been 
>>>defined but I'm trying to get that "definition" effort moving along.
>>>
>>>This is the first one I'd like to address.
>>>
>>>In the coarse of designing the LO for the "prototype" S2 downconverter I 
>>>have not been too concerned with use of the 10 MHz satellite clock. But 
>>>I think it's time for "system" project guidelines to be developed for 
>>>this issue since it can affect the design of all LO's. I have looked for 
>>>guidance on the subject in Eaglepedia and have come up short. Point me 
>>>in the right direction if it's there (and I just couldn't find it).
>>>
>>>I hope I'm not rehashing old discussions (I've only been on the team 
>>>since last October) but here are my questions:
>>>
>>>1) What is the reason for requiring all LO's to be locked to a 10 MHz 
>>>satellite system clock or are they?
>>>
>>>2) Have the performance specifications for the 10 MHz clock been 
>>>developed and what are they (in particular phase noise, frequency 
>>>stability, susceptibility to digital hash, and power level available to 
>>>each using subsystem - to name a few)?
>>>
>>>My apologies for sending to the entire Eagle list but I'm not sure who 
>>>has the responsibility for the clock.
>>>
>>>Probably more questions to follow!!!
>>>
>>>Regards...Bill - N6GHz
>>>
>>>
>>>
>>>_______________________________________________
>>>Via the Eagle mailing list courtesy of AMSAT-NA
>>>Eagle at amsat.org
>>>http://amsat.org/mailman/listinfo/eagle
>>>
>>> 
>>>
>>>      
>>>
>>_______________________________________________
>>Via the Eagle mailing list courtesy of AMSAT-NA
>>Eagle at amsat.org
>>http://amsat.org/mailman/listinfo/eagle
>>    
>>
>
>
>  
>
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