Patent ID: 6914931

Claim:
A method for carrier tracking and spread spectrum code tracking in a spread spectrum communication system, the method comprising the steps of, receiving a spread spectrum input signal having inphase and quadrature components communicating a spread spectrum code modulating a carrier, carrier generating quadrature demodulation signals referenced to a local reference, the quadrature demodulation signals having a carrier phase referenced to the carrier, demodulating the spread spectrum input signal by the quadrature demodulation signals for generating the inphase and quadrature components, code generating early and late code replicas of the spread spectrum code, the early and late code replicas having a code phase referenced to the spread spectrum code, correlating the inphase and quadrature components by the early and late code replicas for generating early and late inphase and quadrature correlation signals, residual generating a residual from the early and late inphase and quadrature correlation signals and from a code phase error state and an amplitude state and a carrier phase error state, calculating a code phase error and an amplitude and a carrier phase error and a carrier frequency error from the residual and a state error covariance matrix and the code phase error state and the amplitude state and the carrier phase error state and a frequency error state, propagating the code phase error state and the amplitude state and the carrier phase error state and the carrier frequency error state from the code phase error and the amplitude and the carrier phase error and the carrier frequency error, Riccati estimating the state error covariance matrix from the code phase error state and the amplitude state, carrier phase adjusting the quadrature demodulation signals by the carrier phase error for reducing the carrier phase between the carrier and the quadrature demodulation signals for tracking the carrier, and code phase adjusting the early and late code replicas by the code phase error for reducing the code phase between the spread spectrum code and early and late code replicas for tracking the spread spectrum code.