Intruder alarm system for large number of locations - uses mains supply wiring to transmit data between stations

摘要

In each room, building or area to be monitored, a transceiver is connected to manual alarm buttons (1), or automatic intruder alarms, e.g. ultrasound, infra-red, pressure plate types, etc. If an alarm condition exists, a Frequency Shift Keyed-FSK- Keyed - FSK - signal is generated by the input circuit (8), and used to modulate (5) a 150 kHz signal which is then fed to the neutral and earth conductors of the mains supply. At all other stations, the signal is demodulated (6) and fed to a decoder (7) which drives an audible alarm (3) and, via a decoder (11), also drives a numerical indicator (4) to show a location number for the alarm.