[time-nuts] 5370B on eBay, carrier phase tracking GPS receiver

[Dr Bruce Griffiths]

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