[time-nuts] 5370B on eBay, carrier phase tracking GPS receiver
brooke at pacific.net
Sun Feb 18 22:36:22 EST 2007
Is there a paper describing the method?
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
Dr Bruce Griffiths wrote:
>Brooke Clarke wrote:
>>Many GPS receivers output carrier phase data but it's usually used in
>>post processing to get survey grade position accuracy. Since the code
>>phase position accuracy is larger than a wavelength the receiver does
>>not know how many integer wavelengths to add. But because of satellite
>>movement this can be figured out later.
>>The exception is the "in development" carrier phase timing which as far
>>as I know can only be done using the Ashtech Z12.
>>The Motorola GPS receivers have carrier phase data available, but when
>>the 8 channel models were current there was no way to use it without
>>spending a small fortune. I think today there's a Motorola binary to
>It is not necessary to use a dual frequency phase tracking receiver to
>significantly improve the disciplining of an OCXO over the performance
>with a timng receiver.
>A single frequency phase tracking receiver is more than adequate.
>The largest problem is determining the ionospheric delay.
>However this can be done by exploiting the difference between the phase
>and group velocities in a dispersive medium (like the ionosphere).
>Carrier phase measurements can be combined with code tracking
>measurements to derive the difference between the phase and group delays.
>Commercial implementations of this technique are available from Quartzlock.
>They use a single channel receiver, which switches between satellites.
>Disciplining an oscillator frequency is an easier problem than deriving
>a geodetic solution, constant time offsets are of little consequence.
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