For improving the performance of multiple-target detection in a colocated multiple-input multiple-output (MIMO) radar system, a constant-modulus-waveform design method is presented in this paper. The proposed method consists of two steps: simultaneous multiple-transmit-beam design and constant-modulus-waveform design. In the first step, each transmit beam is controlled by an ideal orthogonal waveform and a weight vector. We optimized the weight vectors to maximize the detection probabilities of all targets or minimize the transmit power for the purpose of low intercept probability in the case of predefined worst detection probabilities. Various targets’ radar cross-section (RCS) fluctuation models were also considered in two optimization problems. Then, the optimal weight vectors multiplied by ideal orthogonal waveforms were a set of transmitted waveforms. However, those transmitted waveforms were not constant-modulus waveforms. In the second step, the transmitted waveforms obtained in the first step were mapped to constant-modulus waveforms by cyclic algorithm. Numerical examples are provided to show that the proposed constant-waveform design method could effectively achieve the desired transmit-beam pattern, and that the transmit-beam pattern could be adaptively adjusted according to prior information.

The feasibility of one-bit quantization in coast-ship bistatic high-frequency surface-wave radar (HFSWR) is mainly discussed in order to enjoy the advantages of simplicity, low cost and low power consumption. Our theoretical derivation shows that the received signal after one-bit quantization can be expressed as a linear combination of infinite components. These components include the original component and the high-order components that can be regarded as the interference terms. Then, the variation of the magnitude of each component with the signal-to-noise ratio (SNR) is given. To reduce the negative impact of these high-order components on the radar system, the detailed signal forms are analyzed. Furthermore, some comparative simulations of one-bit quantization and traditional high-precision quantization are provided to verify the correctness of our theoretical analysis. Both theories and simulation results indicate that the high-order components can be ignored in coast-ship bistatic HFSWR and that one-bit quantization is effective. Finally, real data analysis also validates the efficiency of one-bit quantization in practice. INDEX TERMS One-bit radar, bistatic high-frequency surface-wave radar, MIMO radar.

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