Sidelobe Suppression Technology Research For Hopped Frequency Waveform

In this paper, studies are carried out to suppress the sidelobes of bothquasi-random/all-random hopped frequency waveforms through both waveformdesigning and signal processing, focusing on the problem of high range sidelobes inhopped frequency radar application.For optimal sidelobe design of quasi-random hopped frequency waveform, therange ambiguity function is entirely decided by its frequencies combination, andthus it is achievable to optimize the signal frequencies combination for sidelobesuppression. By setting sidelobe discrepancy between the matched filtering outputand the ideal expectation as the penalty function, we transform the sidelobesuppression into a minmax optimization. To address the problem, an adaptivegradient search method is proposed, which adjusts the frequencies combinationsaccording to maximum output of the penalty function, and thus reduces the sidelobelevel as much as possible with the signal’s autocorrelation output structurecontrolled. Several key issues for the implementation of the algorithm are discussedwith corresponding solutions given. Extensive simulations show that the proposedalgorithm gives promising results under both cases with discontinuous/continuousspectra.For optimal sidelobe design of all-random hopped frequency waveform,theoretical analysis shows that low sidelobe can be achieved by controlling theoccurrence probability of different frequencies. In this paper, statisticalcharacteristics of the autocorrelation function are analyzed, with the waveformdesign criterion on different cases given. Specifically, weighted window functionand convex optimization are applied under both discontinuous and continuousspectra to design the all-random hopped-frequency waveform with low sidelobe.Simulation results show that by controlling the occurrence probability of differentdiversity pulses, the range sidelobe can be suppressed effectively.From the point of signal processing, this paper utilizes the Adaptive PulseCompression algorithm for sidelobes suppression of hopped frequency waveforms.Stem from mutual interference of different targets, high sidelobes would make anadverse effect on the target detection. The Adaptive Pulse Compression algorithmemploys the range cell estimates form the echo as a priori information to build aunique filter for each range cell, and thus it can suppress the mutual interferencefrom sidelobes of different targets. In this paper, using a discontinuous spectrasignal, we simulate the Adaptive Pulse Compression algorithm under differenttarget distribution. The simulated results validate the Adaptive Pulse Compression algorithm.