Identifying ship echoes in CODAR HF radar data: A Kalman filtering approach

Abstract

Coastal nations have an interest in maritime domain awareness for applications in national security, coastal conservancy, fishery and stewardship of the exclusive economic zones (EEZs) along their coastlines. Maritime situational awareness involves knowing the location, speed and bearing of ships and boats in the EEZ. HF radar is a useful tool in providing ship information in real time. It is especially effective when combined with ship-borne AIS beacons. Our previously developed HF radar and AIS ship detection models estimate signal to noise ratio (SNR) as a function of range, including ducted propagation for the AIS radio signals. However, ship detection is hampered by the high variability of HF echoes from ships. This is due in part to the aspect dependence of ship radar cross-section and to the presence of clutter bands at known Doppler shifts from both the ground and ocean waves. Tracking ships using their HF radar echoes becomes the means for effectively monitoring the presence of ships in the coastal ocean. We explore the application of Kalman filtering to the ship tracking problem, following the techniques described by J. V. Candy. This approach is described and demonstrated with a simple example.

Applying an Adaptive Signal Identification Method to Improve Vessel Echo Detection and Tracking for SeaSonde HF Radar

“…In the same year, Vesecky, J. F (2010) [25] mentioned that the HF radar and AIS ship detection models developed in the past estimate the signal-to-noise ratio (SNR) as a function of range, including the pipeline propagation of AIS radio signals. However, the high variability of HF prevents ships from detecting ship echoes.…”

“…However, the high variability of HF prevents ships from detecting ship echoes. This is due in part to the aspect dependence of ship radar cross-section and to the presence of clutter bands at known Doppler shifts from both the ground and ocean waves [25]. Based on the above interference, the Kalman filtering approach is used to recognize ship signals without changing the radar hardware equipment in the exclusive economic sea area of the United States.…”

High frequency radar for coastal marine monitoring of currents and vessels

“…The Kalman filter approach is one such method. The motivation for this approach and its implementation in the case of SeaSonde-based vessel tracking is described in detail by [10]. Here, only the essential elements are reproduced.…”

“…Each HF radar configuration has its own requirements for identifying potential vessel returns in the Doppler spectra, but the basic requirements to identify individual returns in the spectra, to geolocate the source of the returns, and to associate those returns with subsequent reflections whose movements are consistent with vessel movements are shared by all HF radar systems. To identify a compact target, every HF radar must determine echo strength, range, azimuth and Doppler shift, which is proportional to the target's radial speed [10].…”