In this paper, we compare the performance of different phase modulated frequency hopping (FH) multiple-input multiple-output (MIMO) radar waveforms. The communication symbols are embedded into the FH waveforms under the auspices of dual-function (DF) radar and communications system. In the proposed scheme, each embedded symbol is represented by a sequence of phases. The phase modulated sequence is embedded through multiplication with the radar hops and is transmitted through a MIMO radar platform. Using this scheme, we consider information embedding in MIMO FH radar implementing different types of phase modulated sequence, including phase shift keying (PSK), differential phase shift keying (DPSK) and continuous phase modulation (CPM). We analyze the corresponding ambiguity functions (AFs) in terms of reducing or increasing range and Doppler sidelobes compared to the FH radar without any signal embedding. The spectral sidelobe levels and the complexity of the demodulator at the communication receiver are also examined. It is shown the proposed embedding scheme for DPSK and CPM minimizes the frequency leakage outside the radar signal bandwidth. To demonstrate the effectiveness of proposed scheme, we compare its performance with existing embedding schemes, all for FH radars. It is shown that our approach, in its significant reductions of range sidelobes, permits high data rate transmission. This is made possible because the FH radar can now afford using duplicate hopping code values without the penalty of incurring high correlations, or range sidelobe levels.
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