Synchronization of noncooperative bistatic radar receivers.

摘要

A non-cooperative bistatic radar employs a transmitter-receiver pair which is not designed to be operated together as a system. The transmitter and receiver are physically separated and do not share any kind of communication link. For proper operation, the receiver must be synchronized to such transmitter parameters as waveform, pulse repetition frequency, antenna steering, polarization, and coherent dwell time. Since most, if not all of these parameters are unknown to the receiver a-priori, they must be estimated by monitoring the direct-path signal between the transmitter and receiver.; Bistatic radar fundamentals are reviewed and the synchronization required for proper bistatic radar operation is discussed. The effects of noise and clutter on the use of the direct-path signal for matched filtering are analyzed. Schemes for mitigating those effects are presented. Mechanically-scanned antennas employed by typical host radar transmitters present additional difficulties. The losses in signal-to-noise ratio and offsets in target Doppler measurements created by the antenna pattern nulls and phase reversals are described along with possible techniques for their reduction. Expressions are derived for the accuracy of bistatic range and Doppler measurements in the presence of a corrupted direct-path signal. The introduction of unwanted Doppler frequency components due to a mismatch between the receiver sampling rate and the transmitter pulse repetition frequency are explained and means for synchronizing the sampling rate are discussed. Finally, the effects of digital baseband receiver in-phase and quadrature channel mismatch on bistatic radar performance are examined. Recommendations for future work are presented.