| 摘要 |
A system for transmitting data between a subscriber site and at least one monitoring station, comprising a sensor circuit for generating data responsive to an event at the subscriber site, a first transmission circuit responsive to said sensor circuit and being operable to transmit data in packet form from the subscriber site to the monitoring station over a cellular digital packet data telecommunications network, a second transmission circuit responsive to said sensor circuit and being operable to transmit data from the subscriber site to the monitoring station over a second telecommunications network. A fault detect circuit is coupled to the first transmission circuit for continuously monitoring the operation of the first transmission circuit and the integrity of the cellular digital packet data telecommunications network. A control switch is coupled to the fault detect circuit and controlled thereby for automatically creating a signal path between the sensor circuit and the second transmission circuit. |
