Zero-bias mitigation method based on optimal correlation interval for digital code phase discriminator

In time synchronisation systems, the code phase of the spread spectrum signal is an important characteristic that can provide users with high-precision and unambiguous observation results. However, digital code phase discriminators have limited sampling frequencies that distort the signal correlation peak and generates a zero-bias code-phase estimate. In this Letter, the authors evaluate and analyse the zero-phase deviations of digital code phases. An optimal correlation interval design method, based on a code phase discriminator that can effectively suppress the zero-crossing deviation, is also proposed. The simulation results show that the proposed algorithm can reduce the deviation of 96.5% and effectively improve the measurement accuracy of the code phase.