A code Doppler compensation algorithm in acquisition for high dynamic spread spectrum signals

In high dynamic circumstance, high-speed relative movement between spacecraft and receiver causes not only the carrier Doppler frequency offset but also the code-frequency offset. To tackle the problem of linear code phase drift in fast acquisition, this paper proposes a novel acquisition algorithm based on compensating the code-frequency offset. In the proposed algorithm, the carrier Doppler frequency offset is searched by fixed frequency step, then the code-frequency offset compensation for each dwell in Tong detector can be calculated to eliminate the impact of code phase drift. Furthermore, to reduce the computational complex and hardware resources, a folding structure is adopted in the parallel code phase search. Theoretical and simulation results verify the effectiveness of the proposed algorithm.