Research on direct-path interference suppression for bistatic radar based on GNSS reflected from the ocean surface

The use of global navigation satellite system signals reflected by the sea surface as a remote sensing tool has received considerable attention for over a decade. However, in signal detection processing, the direct-path interference can potentially introduce a bigger obstacle to ocean surface detection than other interferences, such as clutter and radio signals. In order to improve retrieval of the ocean surface parameters, the direct-path interference signals have to be suppressed. The interference suppression based on the improved subspace projection algorithm is put forward in this paper. First of all, the interferential signal is acquired and tracked, then according to the acquired interferential signal parameter, the corresponding disturbance subspace is constructed. Finally, the interference is eliminated using the improved subspace block projection. This method can not only reduce the influence of interferential performance by the tracking error but also decrease computation greatly. It suits the changeable environment and the multi-data sample situation. The analysis of the simulated results has confirmed the validity of this method and provided a basis for the following system optimization design.