Double-differential direct-sequence spread spectrum receiver in underwater acoustic channel with rapidly time-varying Doppler shifts

The Doppler effect is a significant factor that limits the performance of direct-sequence spread spectrum (DSSS) communications. Although constant Doppler can be mitigated through double differential modulation, time-varying Doppler still severely impacts communication performance. The rapid variation in Doppler frequency shift leads to performance degradation in conventional receivers. In this paper, we have enhanced the Doppler estimation algorithm within the conventional receiver, achieving high-precision Doppler estimation results by utilizing the amplitude and phase information from autocorrelation. Data from the lake test demonstrate that the proposed receiver can effectively estimate the time-varying Doppler of the signal and has resulted in improved communication performance.