Under the $6.5 million contract, Raytheon will develop and test advanced mitigation algorithms within its S-band approach and L-band en route primary surveillance radars. Raytheon will also develop and test advanced post-processing tracking algorithms, along with a full PSR modeling and simulation capability that validates enhancements and serves as a tool for rapid development of future improvements.   

Wind turbine farms are prohibited within line of sight of Primary Surveillance Radars and in close proximity to Royal Air Force (RAF) Airfields.  A study was conducted by the UK Government Air Command and Control Operational Evaluation Unit to determine the effects of wind turbine farms on Air Traffic Control Primary Surveillance Radars.  

The study used a scoping exercise over the period from November 3-4, 2004, utilizing the Watchman radar at RAF Valley and the Trysglwyn and Rhyd-y-Groes wind turbine farms. Stage 2, the start of the main trial, was conducted in the period November 23-25, 2004 utilizing the Llandinam (P&L) wind turbine farm in South Wales.  

A Watchman Radar was deployed to a privately owned site in Shropshire, slightly south of the National Air Traffic Services Radar Site at Clee Hill. This deployment provided medium-range data from within the main beam of the radar. Stage 3 was conducted during the period December 13-14, 2004, utilizing the P&L wind turbine farm but with the Watchman Radar on a soft-field site at Llanbister. This provided short-range data from within the auxiliary beam of the radar.

The aim of the Trial was to determine the effects of wind turbine farms on the ATC area and airfield primary surveillance radars. This was achieved by tasking scripted sorties with a variety of aircraft types to over-fly the subject wind turbine farms. The radar video display was assessed during the Trial and radar video output was captured for analysis. The research revealed a shadow region behind the wind turbines within which primary radar responses would be masked. The precise technical reason for this shadow remains unproven. This trial confirmed the presence of this effect for the Watchman. Throughout the Trial, clutter was displayed to the operator as a result of the motion of the wind turbines.  

This displayed clutter was assessed as highly detrimental to the safe provision of Air Traffic Services. ATC operators were unable to differentiate between returns from the turbine blades and those from real aircraft. Therefore, for the purposes of achieving separation, the ATC operator would be obliged to treat turbine-induced returns as though they were aircraft. Finally, the Probability of Detection (PD) of aircraft by the Watchman Radar was considerably reduced when aircraft were overhead, or in close proximity to the wind turbines.