Modified ISM-based frequency domain broadband satellite beamforming

To solve several deficiencies, such as complex beamforming caused by the coherent signals, inadequate information from the passband signals, and difficulties of accurate source location pre-estimation in the current adaptive beamforming of a broadband satellite system, a frequency domain broadband adaptive beamforming algorithm based on the modified incoherent signal-subspace method (ISM) was proposed. The proposed ISM algorithm used a modified multiple signal classification algorithm to improve the spectral estimation of the sub-band signals. Moreover, the coherence of the received data matrix was eliminated by the forward/backward spatial smoothing technique, which effectively overcomes the coherence of the broadband signals and thus obtains good broadband beamforming effect. Simulation results show that the proposed algorithm can effectively obtain broadband beamforming of the coherent signals and solve the problems of broadband interference and beamforming of the auto-correlation signals. Therefore, it can achieve a good beamforming effect with high resolution.