Patent ID: 7599452

Claim:
In a receiver, a method of improving sensitivity in the demodulation of a received signal by said receiver over an arbitrary measurement time epoch, said method comprising the steps of: correlating said received signal with a local replica of pseudo noise code in a coherent fashion over a plurality of time intervals in said time epoch creating a correlation signal; creating a trellis of evenly distributed phase state nodes at each time interval, said creating step comprising: defining a plurality of phase states representing phases evenly quantized over 0 to 360 degrees; defining possible state transitions from and to each phase state node; creating paths between phase state nodes in one time interval and phase state nodes in another time interval according to said possible state transitions; assigning a transition probability to each path; and creating a likelihood metric for each path based on a measured phase of the correlation signal and the transition probability for the path, said measured phase of the correlation signal having a random process approximated utilizing a discrete Markov process; and utilizing a Viterbi algorithm on said trellis to perform a maximum likelihood estimation of a phase trajectory of the correlation signal with said quantized resolution of phase states over 0 to 360° throughout the measurement time epoch.