Objective To overcome the problem of the limitation of working bandwidth due to the phase ambiguity caused by the carrier frequency's variation in conventional time-modulated direction finding, a single-channel direction finding method with nonuniform time modulation is proposed in this paper.
Methods By modulating the signals received by different antenna elements at the same time with nonuniform periods, the amplitude information can be separately mapped to the corresponding modulated frequency without aliasing. With the amplitude ratio independently extracted from the harmonics, single-channel direction finding for the incident signal can be achieved using the lookup table method.
Results The feasibility of the proposed method is verified on the basis of the numerical simulation results. Meanwhile, a wideband non-uniform time modulation system available for 2.4 GHz and 5.8 GHz is constructed and its effectiveness demonstrated, with the results showing that the mean of direction finding absolute error is 0.21° and 0.18° respectively.
Conclusions The proposed method can effectively improve the working bandwidth and has such advantages as a simple structure, low cost, low signal processing complexity and wideband direction finding.
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