DOA Estimation for Wideband Chirp Signals

Conventional DOA estimation approaches suffer from low-angular resolution or relying on a large number of snapshots which are unavailable in numerous practical applications such as underwater array processing. The sparsity-based IAA can work with a few snapshots and has high resolution and low sidelobe levels, but it is only applied to narrowband signals. To solve the above problem, a new FrFT-IAA method was proposed to estimate the DOA of wideband chirp signals with high resolution based on a few snapshots. First, the wideband chirp signal was taken on the Fractional Fourier Transform (FrFT) under a specific order so that the chirp wave in time domain could be converted into sine wave with a single frequency in FrFT domain. Then the steering vector of the received signal can be obtained in FrFT domain. Finally, IAA algorithm was utilized with the obtained steering vector to estimate the DOA of the wideband chirp with a few snapshots. The simulation results demonstrate the effectiveness of the proposed method.