TDOA/FDOA estimation algorithm of frequency‐hopping signals based on CAF coherent integration

The estimation accuracy of time difference of arrival (TDOA) and frequency difference of arrival (FDOA)is determined by the frequency and time distribution, signal energy and noise. TDOA estimation is mainly decided by frequency distribution, while FDOA estimation generally relies on time distribution. Frequency‐hopping (FH) signals have broad distribution in frequency and time domains, the problem of low estimation accuracy for TDOA and FDOA of single‐hop signal can be overcome through multi‐hop coherent integration to improve the use of efficient bandwidth and duration. Focus on the TDOA/FDOA estimation problem of FH signals; this study proposes a high accuracy TDOA/FDOA estimation algorithm, which will conduce high precision of localisation. The cross‐ambiguity function (CAF) of single‐hop baseband signal is first analysed, then the CAF of each hop signal is deduced, and the phase relationship of each CAF is revealed through TDOA and FDOA dimensions. Coherent integration is realised by FDOA normalised compensation and phase compensation. The theory performances of TDOA/FDOA estimation for FH signals are derived, and the influence of the signal parameters on TDOA/FDOA estimate accuracy is indicated. Monte Carlo simulations validate that the performance of proposed coherent integration TDOA/FDOA estimation algorithm for FH signals gets greater improvements than that of single‐hop signal, and the performance improvements accord with the theory analysis well.