Abstract: For the problem of accurate target parameter estimation in distributed coherent aperture radar (DCAR), a DCAR signal model, which takes the Doppler division multiple access (DDMA) waveform as the transmitting waveform and the grid mismatch filtering into consideration, is firstly established. Then the detrimental effects on the target parameter estimation caused by grid mismatch filtering are analyzed and validated, the results of which would decrease DCAR signal coherence-synthetic performance. Finally, two DCAR target parameter estimation methods based on joint global-local search and sparse Fourier transform (SFT) are proposed, respectively. The joint global-local search method weakens the grid mismatch effects by means of setting refined filters locally. To reduce the computation burden, taking advantages of the characteristic that target frequencies are sparse relative to the whole frequency domain, the search method based on SFT is employed, which avoids the traversal search of filters by the gradient descent method. The effectiveness of proposed method is verified by the simulation experiments.

Key words: distributed coherent aperture radar (DCAR), target parameter estimation, grid mismatch, discrete Fourier transform (DFT), sparse Fourier transform (SFT)