On 08/27/2010 07:03 PM, Brooke Clarke wrote:
Hi Bob:
The ultimate is a carrier phase GPS Timing receiver. The early work was
done using Ashtech Z12 models that have a provision for an external 10
MHz oscillator. I have a feeling that the units you're talking about are
a refinement of this approach.
The new L5 frequency of GPS, intended for FAA use, will allow for
civilian two frequency ionosphere corrections in a more straight forward
way than the existing methods (squaring, Ashtech) of using L2 without
knowing the P(Y) crypto keys.
http://www.prc68.com/I/DAGR.shtml#GPSs
The L2C alongside L1 C/A and L5 would allow three-frequency
observations. You would always benefit from doing P(Y) observations
along-side. A modern receiver would be able to make at least 5
observations from the most modern birds, 4 from many and just 3 from the
older birds.
Modern receivers may also support GLONASS so an additional 3
observations may be done.
Cheers,
Magnus
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