[eagle] Re: Eagle 10 MHz Clock

Alan Bloom n1al at cds1.net
Mon Apr 9 20:53:22 PDT 2007


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
> >
> >
> >
> >_______________________________________________
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> >Eagle at amsat.org
> >http://amsat.org/mailman/listinfo/eagle
> >
> >  
> >
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> Eagle at amsat.org
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