The search to provide continuous but affordable shore based surveillance beyond the 200 nautical mile limit led to a reassessment of the potential application of High Frequency (HF) Radar, a technology first implemented in the 1930's and initially used at the beginning of the Second World War. Unlike microwave radars, which are limited to line-of-sight operation, HF radars can achieve true over-the-horizon performance. The early systems were quite rudimentary, needed a great deal of experience to interpret and as a result, never saw practical application once the war was over. The technology is now a practical and affordable surveillance asset because of advances in affordable signal processing power, detection and tracking algorithms, and interference suppression techniques. HFSWR also has applications in fields other than detection of surface and airborne targets including ocean remote sensing, search-and-rescue, iceberg tracking, and managing marine oil spills.

In the first part of my presentation, I will talk about the fundamentals of HF radar technology and describe the way it is operating and show how to validate its performance. It is important to note that HF radar can operate in both sky wave and surface wave modes. I will focus on HF surface wave radars (HFSWR) and talk about the role of this radar in an Integrated Maritime Surveillance System (IMS) introduced by Raytheon.

In the second part, I will talk about noises and clutters that limit the radar target detection range. The HFSWR operates within the congested HF band. Both external interference sources (including co-channel interference, atmospheric noise, and impulsive noise) and self-interference sources (including mainly ocean and ionospheric clutters) affect the received signal. This leaves many challenges for HFSWR's signal processing apparatus to perform properly. The broad variety of interference and noise sources makes HFSWR an attractive benchmark for developing and testing new signal processing techniques. I will show how noises and clutters limit the radar target detection range and then introduce some signal processing techniques to suppress these noises and clutters. The further challenges and work topics to improve the radar performance will also be discussed.

Finally, a short video from two SWR-503 HFSWR systems, operating on Canada's East Coast will be shown. These radars provide simultaneous, all weather, coverage of ocean going vessels and aircraft throughout the 200 nautical miles Canadian EEZ.

Dr. Reza Dizaji is a Senior Research Scientist from Raytheon Company in Waterloo, Ontario. Raytheon's Waterloo facility is a registered center of excellence in the fields of solid-state primary surveillance radars (PSR) and high frequency surface wave radar (HFSWR) technology (nominated for FPTT award), and has been a major supplier of different radar systems for over 40 years.

Dizaji has been responsible and group leader for design and implementation of advanced DSP algorithms for HFSWR and PSR radar systems. He received his Ph.D. (honour) degree in Electrical Engineering from the University of Victoria, British Columbia, Canada. He has developed four US/international patents since year 2000, and has published more than 25 refereed journal and conference papers on different signal processing applications. He held an adjunct professor position at the University of Victoria during 2000-2003.

His main research interest includes sensor array processing, adaptive interference cancellation, clutter suppression, high resolution beam-forming, target feature extraction & classification, and radar pulse coding.