[time-nuts] Disciplining Rubidium

SAIDJACK at aol.com SAIDJACK at aol.com
Thu Apr 24 20:33:01 EDT 2008

Hi guys,
let me play the bad cop here:
  1) Since it is easy and inexpensive to get OCXO's that have  stabilities of 
parts to the E-012 or even E-013 (10811 on Ebay for $50 for  example) over 
time periods of 1/10s out to hundreds or even thousands of  seconds
  2) Since even the best Carrier Phase system won't give you much more  than 
1ns or so accuracy (from the previous threads) per second, and  maybe parts to 
the E-013 over 100s or so - which is worse, or just as good as  our venerable 
OCXO for short time frames.
  3) Since the standard GPS stability seems to overlap our OCXO  stability 
just about at the right point to achieve overall E-012 to E-013  performance at 
about 500 - 2000s intervalls on typical GPSDO's
Then why would we need a carrier phase driven GPSDO? What would  it give us 
in performance that we cannot achieve today with say a good (surveyed  antenna) 
M12M driving an excellent OCXO?
The only advantage I could maybe see is that the carrier phase GPSDO would  
bring us down to E-014 a bit faster than the M12M could?
In a message dated 4/24/2008 14:53:46 Pacific Daylight Time,  
bruce.griffiths at xtra.co.nz writes:


Yes, however you have to do all the required corrections for  ionospheric 
phase delay etc in real time in an external  processor.
These particular receivers have been used in real time arrays to  monitor 
earth deformations of volcanic  fields.


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