Long Distance Target DOA Estimation by MIMO Sonar

A new DOA (direction of arrival) estimator based on MIMO sonar system is proposed to estimate the DOA of long distance targets. First, wideband orthogonal signals are sent out by transmitting sensors and the output of receiving sensors is decomposed into several narrow frequency bands using FFT. The covariance matrix of receiving signals can be expressed as the superposition of the covariance matrices of different frequency bands by exploiting the orthogonal relation of frequency components of the wideband signals. Next, narrowband MIMO method is used to produce the spatial spectrum of every frequency band. Finally, spatial spectrums of all frequency bands are averaged to get source DOAs. Simulations and pool experiment show that this new method produces lower resolution threshold and better estimation performance than traditional phased-array sonar.