Passive direct position determination of multiple emitters transmitting unknown LFM signals

The direct position determination (DPD) method advocates estimating the location of target by processing the raw signals from receivers in central processor, and was shown to outperform the traditional two-step methods, such as the DOA/TDOA approaches. The DPD method has been proved to be effective to locate single emitter in passive radar systems, while the multi-emitter case encounters more commonly in practical problem. In this paper, we consider a passive direct positioning method for multiple emitters transmitting unknown linear frequency modulation (LFM) signals based on short time Fourier transform (STFT) and Hough transform (HT). By applying HT, the unknown number of emitters is determined, then the location and the signal parameters of each emitter can be estimated by a six-dimensional grid search. However, it is still computationally intractable thus limited in many realistic applications. By additively combining with the STFT, one applied and efficient method, i.e., HT-DPD-STFT, is designed. Simulation results show that the proposed HT-DPD-STFT approach obtains efficacy and advantageous localization accuracy.