Non-uniform sub-bandwidth orthogonal frequency division multiplexing frequency modulation signal waveform optimization method

Abstract

The invention discloses a non-uniform sub-bandwidth orthogonal frequency division multiplexing frequency modulation signal waveform optimization method, and mainly solves the problems that the radar signal detection capability is insufficient and the fixed emission waveform of a radar system is mismatched with the current environment state in the prior art. According to the implementation scheme, the method comprises the following steps of: solving an ideal waveform energy spectrum density epsilon opt (f) under a maximum signal-clutter-noise ratio criterion according to spectrum distribution information of clutter, noise and a target; establishing a relation model between the waveform parameter of the orthogonal frequency division multiplexing linear frequency modulation signal and the energy spectrum density of the orthogonal frequency division multiplexing linear frequency modulation signal; establishing a target function by taking the minimum mean square error between the energy spectrum density of the waveform to be optimized and the energy spectrum density of the ideal waveform as a criterion; and solving the target function to obtain parameters of the optimal waveform. According to the method, the signal-clutter-noise ratio of the output signal is increased, the target detection performance of the radar is improved, the signal waveform has the characteristics of large time width and bandwidth product value and low time domain peak-to-average power ratio, and the method can be used for clutter suppression.

Description

technical field [0001] The invention belongs to the technical field of digital signal processing, and in particular relates to a non-uniform sub-bandwidth OFDM signal waveform optimization method, which can be used to suppress clutter and improve the signal-to-noise ratio of radar output signals. Background technique [0002] An important constraint in improving the performance of traditional radar target detection and recognition lies in the mismatch between the fixed transmission waveform of the existing radar system and the current environment state. Due to the dynamic changes of the environment, it is generally difficult for radar to achieve the expected detection effect. Optimizing the transmission waveform according to the current environmental knowledge will greatly improve the detection performance of the radar system. Clutter is an important interference factor in the radar working environment, so the waveform design work in the clutter environment is extremely impo...

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Problems solved by technology

[0004] Wang Wenqin proposed a method suitable for MIMO SAR in "MIMO SAR OFDM chirp waveform diversity design with random matrix modulation, IEEE Transactions on Geoscience and Remote Sensing, vol.53, no.3, pp.1615-1625, Mar.2015." Orthogonal frequency division multiplexing linear frequency modulation signal waveform design method, which modulates a group of basic waveforms through a random matrix to obtain an orthogonal frequency division multiplexing linear frequency modulation signal waveform with uniform distribution of sub-bandwidth and sub-time width. Although the waveform has It has the advantages of large time-width-bandwidth product, low peak-to-average power ratio in the time-frequency domain and low range-Doppler coupling, but it cannot effectively suppress clutter due to its high time-domain autocorrelation function sidelobe and flat spectrum distribution.

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