HF hybrid sky-SWR system based on MIMO technology

High-frequency (HF) hybrid sky-surface-wave radar (SWR) is very useful for sea-state extraction, and the rich content echo information is very meaningful. On the basis of the multiple-input–multiple-output technology, a new HF hybrid sky-SWR system is designed. The radar transmits multi-frequency signals and synchronously receives the echoes through multiple channels. By adding linear phase shift between frames of the frequency-modulated interrupted continuous wave, the multi-frequency echo signals can be separated in the Doppler spectrum after two fast Fourier transforms. It expanded the HF hybrid sky-SWR from the single-frequency mode to a simultaneous multi-frequency one. Through this system, the ocean dynamics parameters at different frequencies can be simultaneously obtained. Moreover, multi-angle information can be obtained to use for the inversion of the sea surface current and its temporal and spatial variations. Since the transmitter site and the receiver site of the radar are placed in different areas but synchronously work with multiple channels, it is very universal and convenient for network configuration and extension. As validated by the ocean exploration experiment, this system is feasible and reliable.