Offshore Surface Surveillance with HF Radar
Abstract
HF groundwave radars are routinely deployed for ocean roughness and current monitoring. These low-powered radars see ship traffic as annoyance echoes, and they employ filtering techniques to remove ship and boat echoes. A simple processor addition to such radars could provide surface target tracks out to the tens of miles distances. Neptune in the UK and the Moscow Institute of Long-Wave Radiowave Communications offer radars for harbor management and monitoring coastal traffic. In this report, the performance of HF groundwave radar for surface targets is predicted for over the sea paths. The radar antenna location is taken to be at the shoreline and well coupled to a sea with typical ocean salinity. The radar parameters selected are easily achieved. The nominal 10 MHz operating frequency is a compromise between large antenna size required by low frequency operation and higher path losses experienced at higher frequencies. A transmitter average power of 1 kW 30 dBw) and a transmitter-receiver antenna gain product of 30 dBi are selected; these values are somewhat less than were suggested in a sales brochure. At square-meter target yields a 20 dB signal to noise ratio (SNR) at 40 nmi. At slow speeds, the target can be obscured by the sea echo (dependent upon the spatial resolution cell size); this emphasizes that for small targets, resolution cell size is more important than energy density. Under relatively calm conditions, the target would be detectable at all speeds except zero, where the target might be obscured by land returns from antenna side lobes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 16, 2001
- Accession Number
- ADA398493
Entities
People
- James M. Hendrick
Organizations
- United States Naval Research Laboratory