[time-nuts] Building a GPSDO & trouble using Jupiter-T

Hal Murray hmurray at megapathdsl.net
Fri Feb 3 01:49:53 UTC 2012

> Remarkably, the simplest and still one of the best GPSDO I've tested was the
> 10 kHz Jupiter and analog PLL-based standard by James Miller. It performed
> superbly. It's the 4th GPSDO at: http://www.leapsecond.com/pages/gpsdo/ 

In hindsight, that doesn't seem too surprising.

I'm not a Juniper wizard.  I could be way off here.

I'm assuming the Jupiter does phase jumps every second and uses DDS like 
mechanisms within each second.

The DDS will make spurs.  A simple analog filter will get rid of most of 
them.  What gets through will be close in.  The phase jumps turn into close 
in phase noise where "close" is under 1 Hz.

How would you measure that sort of phase noise?

These are my opinions, not necessarily my employer's.  I hate spam.

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