Abstract: In a vehicle presence detection system for controlling traffic signal lights at a road intersection, the vehicle detection is performed by targeting vehicles at the location of interest with an FMCW radar beam. The radar can be switched repeatedly between the FMCW mode, for vehicle presence detection, and a doppler mode, for vehicle movement detection. Signal data representing the background of the scene viewed by the radar beam are stored for use by circuitry that determines whether an apparent vehicle presence detect is a true vehicle detect; the background signal data is repeatedly updated, as necessary, as the system cycles. Temperature compensation is provided and entry into the FMCW mode is inhibited if a voltage-controlled oscillator provided for generating the emissions has not settled down after any such compensation.