On 7/6/13 9:29 AM, Joseph Gwinn wrote:
Code/Carrier Frequency Coherence: The lack of coherence between the
broadcast carrier phase and the code phase shall be limited. The short
term (<10sec) fractional frequency difference between the code phase
rate and the carrier frequency shall be less than 5x10-11 (one sigma).
Over the long term (<100 sec), the difference between the change in the
broadcast code phase (convert to carrier cycles) and the change in the
broadcast carrier phase shall be within one carrier cycle (one sigma).
This is interesting. Does it imply that they regenerate the code on board?
Very unlikely, because then the bird would have to understand every
possible code, including those not invented when the bird was launched.
the class of codes used is pretty restricted (e.g. Gold/Kasami codes
with 10 bit generators), at least for GPS. Most correlator and
generator implementations are somewhat programmable, at least as far as
the tap configuration and the initial load.
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