[EMAIL PROTECTED] wrote: > 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. > Wildly inaccurate statement #2. A carrier phase system gives can have noise as low as 20 picoseconds over the 1-100s time interval. Upper time interval limit may be a little larger. > > 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? > > They can be almost 2 orders of magnitude better than you assume for short time intervals. 8E-14 performance from 2 to 20 s with 1E-14 at 1 day has been claimed when carrier phase disciplining a BVA 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? > > Carrier phase disciplining should allow very good performance even with lower spec OCXOs. > bye, > Said > > Bruce
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