Ambiguity Optimization Using Frequency-Hopping Waveforms

Recently, the concept of MIMO (multiple-inputmultiple-output) radars has drawn considerable attention. In traditional SIMO (single-input-multiple-output) radar, the transmitters emit coherent waveforms to form a focused beam. In MIMO radar, the transmitters emit orthogonal (or incoherent) waveforms to increase the spatial resolution. These waveforms also affect the range and Doppler resolution which can be characterized by the ambiguity function. In traditional (SIMO) radars, the ambiguity function of the transmitted pulse characterizes the compromise between range and Doppler resolutions. In the MIMO radar, since many transmitting waveforms are involved, their cross-ambiguity functions enter into the signal design problem. In this paper, frequency hopping codes are used to generate these orthogonal MIMO radar waveforms. A new algorithm for designing the frequency hopping codes is proposed. This algorithm makes the energy in the corresponding ambiguity functions evenly spread in the range and angular dimensions.