Conventional stepped-frequency (SF) waveform utilises the frequency step between pulses to span a wide bandwidth. However, the frequency step size is limited by the width of the pulse to prevent the grating lobes, and...
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Conventional stepped-frequency (SF) waveform utilises the frequency step between pulses to span a wide bandwidth. However, the frequency step size is limited by the width of the pulse to prevent the grating lobes, and the first lobe is about -13dB due to the uniformly sampling in frequency. Modulating the pulses [e.g. phase-coded (PC) modulation or linear frequency modulation] can increase the frequency step size and improve the performance of the sidelobes, but the sidelobes of the modulated SF waveform are still not the best. In this study, a PC frequency-hopping (PCFH) waveform to achieve optimal extend-range correlation sidelobes is presented. The presented waveform applies non-linear frequency evolution, optimal frequency order and different polyphase code to each pulse. In comparison to the SF waveform, the PCFH waveform has much higher degrees of freedom for suppressing extend-range correlation sidelobes. The authors propose a design scheme, which sequentially optimises the interpulsefrequency, the FH order and the intrapulse-polyphase code to achieve the optimal extended-range correlation sidelobes. Simulation results validate the performance of the optimised waveform and the feasibility of the involved design method.
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