Abstract: Disclosed are a device for the detection of S mode responses received by a secondary radar receiver and its use for the filtering of the pulses contained in this response. The device furthermore comprises means to detect a signal S, means for the real-time computation of the mean values of magnitudes characterizing the pulses that belong to the response, and means for the filtration, by comparison, of the values of the magnitudes measured on each pulse detected with the mean value of the corresponding magnitude.

Abstract: A spectrum analyzer comprises a plurality of filters each provided with a low-pass output and a high-pass output both having the same cutoff frequency which is different in the case of the different filters. Switching means are provided for periodically connecting pairs of filters in cascade during a first time interval between one input for signals to be analyzed and a filtered-signal transmission channel assigned to each pair of filters. One of the filters of each pair has a high-pass (or respectively low-pass) output connected to the input of the other filter whose utilization output is the low-pass (or respectively high-pass) output. The switching means also have the function of periodically establishing a cascade connection during a second time interval between pairs of filters which are different from the first pairs. In the case of one filter, the output utilized during the second time interval is different from the output utilized during the first time interval.

Abstract: A physical quantity such as temperature, infrared radiation or smoke is detected by means of a conversion device for emitting an alarm signal whose amplitude is representative of the intensity of the physical quantity. The detector comprises a unit for measuring relative variations of the signal in time, for comparing them with a preset threshold level and for actuating the alarm when they exceed the threshold level.

Abstract: The detector comprises a transducer designed to convert to an electrical signal a physical quantity which is representative of an abnormal phenomenon. The output of the transducer is connected to one input of a comparator whose output is connected to a delay circuit. The output of the delay circuit controls a signal generator, the output of which is connected to the other input of the comparator, the signal delivered by the comparator being representative of the time-dependent variations of the signal delivered by the transducer.

Abstract: A physical quantity such as temperature, infrared radiation or smoke is detected by means of a conversion device for emitting an alarm signal whose amplitude is representative of the intensity of the physical quantity. The detector comprises a unit for measuring relative variations of the signal in time, for comparing them with a preset threshold level and for actuating the alarm when they exceed the threshold level.

Abstract: The connections between the two inputs of an amplifier and the two outputs of a signal source as well as between the outputs of the amplifier and the inputs of a downstream output element into which the amplifier delivers a signal are inverted periodically and simultaneously and integration is carried out between the outputs of the amplifier and the inputs of the output element. In addition, the inputs of the amplifier are short-circuited periodically, the frequencies of inversion and of short-circuiting being multiples of each other.