A Residual Frequency Offset Estimation Method Based on Range Migration Fitting

Recently, researchers have proposed an emitter localization method based on passive synthetic aperture. However, the unknown residual frequency offset (RFO) between the transmitter and the receiver causes the received Doppler signal to shift, which affects the localization accuracy. To solve this issue, this paper proposes a RFO estimation method based on range migration fitting. Due to the high frequency modulation slope of the linear frequency modulation (LFM)-modulation radar signal, it is not affected by RFO in range compression. Therefore, the azimuth time can be estimated by fitting the peak value position of the pulse compression in range direction. Then, the matched filters are designed under different RFOs. When the zero-Doppler time obtained by the matched filters is consistent with the estimated azimuth time, the given RFO is the real RFO between the transceivers. The simulation results show that the estimation error of azimuth distance does not exceed 20 m when the received signal duration is not less than 3 s, the pulse repetition frequency (PRF) of the transmitter radar signal is not less than 1 kHz, the range detection is not larger than 1000 km, and the signal noise ratio (SNR) is not less than –5 dB.