Bit synchronization methods and their performance for HSGPS receivers

One problem with the high sensitivity global positioning system (HSGPS) receivers is that the bit edge detection rate decrease dramatically when use the traditional bit synchronization procedure which is called histogram method (HM) in weak signal environment. We propose a hard decision method (HDM) a soft decision (SDM) to enhance bit synchronization efficiency of HSGPS in weak signal situations. Simulation results shown that when the bit detection time is 2 second and the frequency error is 0 and C/N0=19 dB-Hz, an edge detection rate of 85% for HDM can be acquired. when the frequency error is 100 Hz, C/N0= 21 dB-Hz, and other situation remains the same, the edge detection rate is 92%, in both situations SDM is 1 dB better than HDM in bit synchronization sensitivity.