A Joint Estimation Method of Time Difference and Velocity Difference for Wideband Frequency Hopping Signal Based on Coherent Accumulation

‍ ‍It was impossible to directly estimate the Doppler frequency difference of the frequency-hopping observation signal containing multiple pulses in the passive positioning scenario of moving multi-station because the wideband frequency-hopping communication signal’s carrier frequency hopping results in a changing Doppler frequency shift. If only the single-hop signal’s time-frequency difference is evaluated， the estimation precision won’t be sufficient for locating. This study suggested a joint time difference and Doppler velocity difference estimation approach for coherent accumulation of multi-pulse coherent accumulation of frequency hopping signals in order to address this issue. Firstly， a time difference-Doppler velocity difference model was established for the wideband frequency hopping observation signal. Then， each pulse pair’s frequency domain conjugate product was phase-compensated and accumulated. Finally， by looking for the two-dimensional peak value of the cost function， the predicted time difference and Doppler velocity difference of the multi-pulse frequency hopping signal were discovered. The simulation results demonstrated that the method proposed in this paper had a significant improvement in estimation accuracy compared to the single-hop method and the multi-pulse non-coherent accumulation method， and can be close to CRLB under the condition of medium and high signal-to-noise ratio. This demonstrates the correctness and precision advantages of the proposed method.