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Session C5: Modernized and Emerging GNSS

Rapid Synchronization for Spread Spectrum Communication System
Kerry Frohling, Iris Technology
Location: Grand Ballroom E
Alternate Number 1

Peer Reviewed

In satellite navigation systems, Time to First Fix (TTFF) has been a persistent problem since the introduction of the GPS system. In this paper, Iris Technology will present new coding and synchronization methodology that would allow rapid synchronization with a new P code like sequence with no a priori knowledge of the current system time, given the transmitted sequence is a maximal length sequence. If the transmitted sequence is a member of a Gold code family, the receiver can determine the time and which member of the Gold Code family was transmitted.
The solution being proposed implements the Gold Synchronization Algorithm developed by Dr. Robert Gold along with an Iris Technology developed code generator to provide a system that allows rapid synchronization with very long codes with no knowledge of transmitter system time. This system would be able to determine which of a set of Gold codes was transmitted and the phase (time) of the code being received. This system would provide rapid acquisition of precise time estimates and would allow the underlying codes to be changed without modification of the system hardware.
The system proposed would be able to rapidly acquire a precise time estimate from a single transmitter that could be further refined by receptions from other transmitters. This would allow precise time and positions estimates to be obtained in a matter of seconds. Further, if it is desirable to change the code used as the precision code (or equivalent) this could be done on the transmitter end without modification to the receiver hardware as long as the new code is selected from the same set of Gold codes (there are over 8 billion Gold codes in a week long set). This would provide a system that provides both rapid acquisition and code flexibility.



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