[time-nuts] Need 10 MHz for DSN space-probe hunting

Charles Steinmetz csteinmetz at yandex.com
Wed Sep 14 12:01:09 EDT 2016

> Just wanted to add, their US distributor has one with a custom xtal that claims even lower phase noise and has provided a plot comparing the two

I see the US distributor says the "custom" unit's phase noise 
"improv[es] on an already impressive figure" of the stock unit.  But in 
reality, even the custom unit doesn't have an "impressive" PN figure -- 
the phase noise is still at least 10dB worse than a real GPSDO.  It 
appears that the outputs are generated by a DDS or similar, so that is 
not surprising.  Good for frequency agility, lousy for frequency 
stability and spurious outputs.

This thing has its place in the world of clocks, but it is *not* a 
precision GPSDO.  It is not even in the league of a number of hobbyist 
and DIY designs.  I wish people would stop recommending it to people 
whose application calls for a real GPSDO (such as multiplying up to the 
GHz region).

Best regards,


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