In a wireless communication system, the communicating stations reduce their transmitting power level when they detect interference exceeding a certain level. Interference is detected by down-shifting the received signal to place the desired signal in the baseband, then sampling the down-shifted signal, first at a sampling frequency high enough to catch the interference, then at a lower sampling frequency that excludes the interference. This system is useful for vehicle-to-vehicle communication in an environment in which vehicle-to-roadside communication may also be present at various nearby frequencies, because it does not require exact knowledge of the interfering frequencies and allows communication to continue even when interference is present.