How does interference between multiple automotive radars affect detection performance?

Interference between multiple automotive radars operating in the same 76-81 GHz band affects detection performance by raising the noise floor at the victim radar's receiver, reducing the signal-to-noise ratio and therefore the maximum detection range and the ability to detect small targets. When two FMCW radars illuminate each other, the interfering signal appears as a short burst of wideband energy in the victim radar's beat signal because the interferer's chirp has a different slope and timing, creating a beat frequency that sweeps rapidly across the victim's receiver bandwidth during the brief time the two chirps overlap. This interference manifests as a raised noise floor (typically 10-30 dB in affected range bins) rather than ghost targets, because the interference energy is spread across multiple range bins. As automotive radar density increases (potentially 10-20 radars per vehicle, hundreds of radars at busy intersections), the probability and severity of interference increases. Mitigation techniques include randomization of chirp start times and chirp slopes to reduce the probability of coherent interference, interference detection and excision in the time domain (blanking the affected samples), CFAR detection with elevated noise floor adaptation, and emerging standards for coordinated waveform allocation.