Abstract: Monitoring and/or alarm device and process including a central unit, at least one intrusion detection peripheral facility, signalling elements and radio link elements allowing radio links on several redundant channels between the central unit and at least one intrusion detection peripheral facility, via which channels this peripheral facility is able to transmit signals to this central unit and wherein elements check the capacity or availability of each of the link channels to transmit the expected signals, elements count the number of available channels and/or the number of unavailable channels and transmission elements transmit to the signalling elements a control signal corresponding to the number of available channels and/or to the number of unavailable channels so as to selectively activate these signalling elements as a function of the state of the control signal.

Abstract: Process and device for receiving radio signals include a receiver having an antenna and a reception circuit exhibiting a received-signal output. Sampling elements make it possible to endow the receiver with reception phases separated by phases of absence of reception. Adjustment elements make it possible to operate the reception circuit on particular frequencies of operation. A generator delivers a reference signal on a nominal frequency. Sensors act on the adjustment elements so that the reception circuit operates, during a sensing period, successively on frequencies including the nominal frequency. Drive elements divide the sensing period into sensing phases (Ps), the duration of each of which is at most equal to the duration of the phases of absence of reception of the reception circuit and actuate the signals generator and the sensors during these sensing phases.

Abstract: Monitoring and/or alarm device and process including a central unit, at least one intrusion detection peripheral facility, signalling elements and radio link elements allowing radio links on several redundant channels between the central unit and at least one intrusion detection peripheral facility, via which channels this peripheral facility is able to transmit signals to this central unit which are expected by the latter and wherein elements check the capacity or availability of each of the link channels to transmit the expected signals, elements count the number of available channels and/or the number of unavailable channels and transmission elements transmit to the signalling elements a control signal corresponding to the number of available channels and/or to the number of unavailable channels so as to selectively activate these signalling elements as a function of the state of the control signal.