Abstract: A monitor receiver incorporating a device for reducing the false alarm ratio comprises a frequency changer, a wobbulated oscillator, two band pass filters of which the central frequencies are constant and staggered, two logarithmic amplifiers and two energy detectors, which makes it possible to measure the energy on two staggered frequencies. The logic alarm signal supplied by the comparator is transmitted via a gate inhibited by means for detecting pulsed noises having an energy level greater than a value S', and validated by means of detecting signals of higher energy than a value S". The threshold values S' and S" are calculated by calculator means as a function of the mean value of the energy of the medium and long term persistent noise on frequencies close to the frequency monitored.