An automatic alarm system with monitoring signal analysis

摘要

A self-testing data communications system suitable for use with an alarm system. In a first aspect the communications system is capable of modifying an operational parameter such as the input signal sensitivity of a receiver located at a monitoring station during receipt of a supervision signal from a remote alarm device, in order to ensure that a non-supervision alarm signal will be properly received when the operational parameter is again returned to its normal state. In a second aspect, the receiving element of the communications system is capable of receiving the message simultaneously at two different sensitivity levels, and during a supervision message, the lower sensitivity path is used in order to ensure that non-supervision alarm messages are received with an adequate signal margin. In a third aspect, the receiving element of the communications system is capable of measuring the signal strength (RSSI) of the received message signal and comparing it, if it is a supervision message, to a predetermined threshold value. When the supervision RSSI signal is above the threshold, the received message is passed to the control as being validly received; when the supervision RSSI signal is not above the threshold, then the message is ignored.