Evaluation of an HF-radar ship detection and tracking algorithm by comparison to AIS and SAR data

Since several years, High Frequency (HF) Over-The-Horizon (OTH) radar is used to measure océanographie parameters, such as currents, waves, and wind direction over large areas up to 200 km off the coast. Cost effective low power systems transmitting less than 50 Watts have been developed, e.g. the WERA (WEUen RAdar), and are now commercially available. Besides their applications in oceanography within coastal monitoring systems, these systems can also be used to detect and track ships, if they are modified for this functionality. A ship detection and tracking algorithm for HF-radar has been developed at the University of Hamburg (UHH) in cooperation with the Technical University of Hamburg-Harburg (TUHH). A first evaluation of this algorithm has been done using a data set acquired at Figueira, Portugal, using an 8 MHz WERA system. In May 2009, the NATO Undersea Research Centre (NURC) initiated a measurement campaign in the Ligurian Sea off La Spezia, Italy, which involved two WERA HF-radar systems operated at 12.5 MHz, one directional waverider and a meteorological buoy. In addition AIS data were recorded and satellite borne synthetic aperture radar (SAR) images were acquired. This paper presents preliminary results which show the effectiveness of the HF-radar as a long range (~130 km) continuous-time coverage surveillance system, despite of its low spatial resolution of 1.5 km. The performance of the HF-radar ship detection and tracking algorithms are evaluated by comparison to AIS and SAR. The detection error found for this data set is less than 1 km for ~68% of the comparisons between HF-radar and (AIS) reported locations, which is comparable to previous results from the Figueira data set.