[time-nuts] GPS Locked and Unlocked Performance Comparison

[SAIDJACK at aol.com]

Hi Tom,
 
I wonder how the Miller unit would perform if the GPS is kept alive during  
holdover.
 
If the Jupiter continues to generate the 10KHz and 1PPS from it's  internal 
TCXO even without GPS reception then I would expect the holdover  performance 
to degrade to that of the TCXO if the unit goes into antenna-related  holdover?
 
Unless the Miller design removes the 10KHz reference from the PLL if there  
are less than a certain number of sat's received etc. Should be possible to add 
 that feature by monitoring the RS232 output, gating the 10KHz, and clamping 
the  EFC control voltage -  if that feature is not already  there.
 
That's a nice behavior trait of the Motorola receiver: it shuts off it's  
1PPS when there are less than 4 Sats etc (in TRAIM mode).
 
It's surprising what kind of performance can be achieved with the 10KHz  
locking the OCXO through an Exor gate. Then again that design get's to compare  
phase 10.000 times more often per second than all of the other 1PPS based PLL's  
:)
 
bye,
Said
 
 
In a message dated 2/13/2008 10:47:44 Pacific Standard Time,  
tvb at LeapSecond.com writes:

The  other is to remove the power/data connector to the Jupiter
board (which is  what I did).





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