A detector for indicating reception disturbances during ultrashort wave broadcast reception by demodulating of intermediate frequency signals has a frequency modulated demodulator with a demodulation characteristic line formed so that a controlling region within which the output signal increases with increasing frequency deviation from a carrier frequency extends advantageously over the entire band width of the ultrashort wave intermediate frequency channel and is significantly greater than the maximum frequency deviation of the intermediate frequency carrier modulated with the basic band signal in the frequency, and the output signal of the frequency demodulator is supplied to an evaluating circuit at whose output the exceeding of a predetermined frequency disturbance deviation threshold is indicated by a logic signal.