Magnus Danielson wrote: >> http://tycho.usno.navy.mil/ptti/ptti99/PTTI_1999_405.PDF >> > > There is another paper just before it. There is also a patent for a > specific > form of implementation. > > >> Note they used an Oncore VP, the Superstar has a better carrier phase >> tracking.performance. >> > > What they did was that they hooked their Oncore VPs up to cesium beams > for > test purposes. Locking that clock with a not-so-perfect but sufficient > for > the task ratio. > > You can do about the same without too much difficulty, but the Allstar, > Superstar and Superstar II receivers belong to those that is built out > of the > Zarlink chipsets An interesting product originating from Mitel (Mike and Terry's lawnmowers later became MITEL - according to their local rep about 20 odd years ago) > which all feature an interesting issue, the use of a 10 MHz > TCXO. Now, this frequency should be fairly know to us time-nuts, no? ;) > > Wiring in an externally supplied 10 MHz should not be all that difficult. > The receiver is now effectively a high resolution phase comparator > between the > selected sats and the timing source used for reference. The PPS output > of the > receiver is not used for reference, but rather the carrier phase > pseudo-ranges. > Either you tap the pseudo-range data out and do the dirty stuff > outside, or > you have the receiver do all the calculations. Having a reciever do some > interesting corrections on pseudoranges may be a bit harder thought. > > Anyway, if you do things properly, it will be a much better solution than > looking at that PPS. > > However if all you have is a 10811 it will limit the short term satbility of such a GPSDO. The phase carrier measurements will have a lower noise floor than the 10811 for tau > 10s or so. A better oscillator (FTS1200, FTS100 Oscilloquartz OSA8607 etc.) will have a significantly lower noise floor. However since the latter generally have 5MHz outputs a low phase noise frequency doubler is required. > Cheers, > Magnus > > Bruce
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