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Vessel tracks detected by HF radar
High Frequency Surface Wave Radar (HFSWR) has the unique ability to remotely sense targets and environmental parameters over the sea beyond the horizon limit associated with conventional radar systems.
This capability can provide round the clock surveillance of naval vessels, aircraft and weather conditions beyond the horizon, a capability which cannot be offered by satellite or other sensors. The systems is ideal for homeland defence, i.e. day/night operation, long endurance, all weather and large area search capability.
The Advanced Technology Centre has had a long term interest in HF radar and in recent years has designed and built an HFSWR demonstrator for use in maritime surveillance and sea-state sensing. The radar's capabilities and performance offer a unique facility for maritime and off-shore operations, providing both a vessel tracking and a real time environmental monitoring capability.
The demonstrator is currently deployed on the Essex coast looking out over the Thames Estuary and North Sea, and is used as a demonstration tool and to support on-going research. The radar is fully automated and uses advanced digital signal processing. A 32 element receive antenna array with digital beam forming is used to provide fine azimuth resolution of targets in the coverage area. Adaptive algorithms are employed to automatically detect and track targets, and extract environmental parameters from the Radar Doppler spectrum. The radar data products include vessel plots and tracks, surface current vectors, wind vectors, wave height and wave period.
The radar track display provides a geographical view of vessels in the coverage area. Each track is shown as a track vector indicating the direction and speed of the vessel track, with a persistence trail indicating the track history.
A point and click interface is used to pull up detailed track parameters in a track tote.
The demonstrator uses only 36watts mean transmit power, and is designed for detection and tracking of vessels at up to 80km from the radar site, well beyond the radar horizon. Alternative configurations can extend the operational
range to 200km and beyond. High quality vessel data is produced, with range and azimuth uncertainties of 520m and 0.69degrees respectively at the plot level.
The radar is fully automated and is operated remotely, via an ISDN digital data link, by an operator's console located at the ATC. The operator's console is a high performance computer workstation, which processes and displays the radar data in real time. The point and click interface provides a simple and effective interface to the radar displays and control panel.
Digital data recording and playback is also incorporated.
The antenna site is not manned and the radar requires little maintenance, hence the system is ideally suited to marine surveillance duties located at a central operation centre. The radar display is easily networked to additional display terminals and using a standard ISDN telephone line, the display can be placed at an operation centre almost anywhere in Europe.
The environment and monitoring capabilities of the radar allow real time measurement of the sea surface and wind conditions in the radar coverage area, simultaneous with normal vessel surveillance.
Measured environmental data is presented on a 5km square measurement grid, making assimilation into oceanographic and meteorological models very straight forward.
The wind speed and direction are displayed on the 5km square grid using a stick vector to indicate strength and direction. The vectors are colour coded to indicate the measurement quality factor.
The surface current is also displayed on the 5km square grid using a stick vector. Using one radar system only the strength of the radial current, toward or away from the radar, is shown. Using two systems the full current vector can be obtained. Significant wave height and wave period are also measured.
The radar system provides a unique combination of vessel data, and data on the environment the vessel is working in,
at ranges beyond the radar horizon. This combination is ideally suited to many types of marine operation. Application areas include:
- Economic exclusion zone monitoring.
- Fisheries protection.
- Off-shore oil and gas production.
- Marine emergency management.
- Coastal planning and environment management.
- Oceanographic and meteorological.
