Abstract: A method is disclosed for enforcing a speed limit in a zone of a roadway, such as a construction zone, where the ability of an officer to stop a speeding vehicle may be limited. A Doppler traffic radar unit and a video camera are set up at an off-road surveillance site typically adjacent the zone, and aimed at a common target area in the zone through which vehicles will sequentially pass. The speed information, Doppler audio and video are transmitted from the surveillance site to a more distant off-road location (remote site) that is accessible from the roadway, where a patrol car is located. The patrol car at the remote site receives the transmission and is equipped with an in-car video/audio system having a video buffer and a record mode.

Abstract: A traffic radar captures the patrol vehicle return signal by saving the patrol return when the radar system is placed in a standby state. If the radar is in standby for more than a predetermined period of time before reentering a transmitting mode, the system searches for a new patrol signal within a speed window around the saved patrol signal speed. If the radar is in standby for less than the predetermined period of time, the system initially searches for a new patrol signal over a range that excludes an interval around the saved patrol signal speed. If the new patrol signal is not found, then in a subsequent search the interval is included in the searched spectrum.