Self-Organized Synchronization Based on a Chirp-Sequence Waveform for an HF Ocean Radar Network

HF ocean radars are usually installed along the coast and deliver remote sensing information by transmitting a radio signal with an operating frequency between 3 and 30 MHz. The frequency band allows for a large coverage of ocean surface that could extend more than 200 kilometers offshore depending on the transmit frequency and other operating conditions. To provide a dense coverage of the sea surface, the installation of ocean radars in a radar network may require that the transmitting and receiving units of a radar network demand time synchronization between the units to perform correct space-time measurements of ocean parameters. In this paper, a self-organized synchronization for HF ocean radars is considered without the use of Global Positioning System (GPS) devices. In the case of multiple transmitters, the power peaks are observed in spectra simultaneously for each of the transmitters; hence the time shift can be estimated separately for each of them. The self-organized approach is very useful for the case of multiple transmitters and receivers in a radar network as well as in multiple-input-multiple-output (MIMO) radar configurations, which utilize the feasibility of occupying less space for a HF radar receive antenna while maintaining the high spatial resolution of the radar data.