Abstract: A security apparatus having two control and communications units adapted to monitor a system and to establish communications over a connected telephone line and to transmit an alarm upon the occurance of a predetermined event in the system. The first control and communications unit produces a characteristic signal when it is operational; and the second control and communications unit is adapted to monitor the characteristic signal produced by the first control and communications unit and to establish communications over the connected telephone line and transmit an alarm upon interruption of the characteristic signal. The characteristic signal is preferably a tone of predetermined frequency.

Abstract: A personal security system includes at least one movable transmitter adapted to produce an emergency signal transmission when activated and a plurality of transceivers adapted to receive emergency signal transmissions from the movable transmitter. The received strength of an emergency signal received by one of the transceivers is compared with the received signal strength of an emergency signal received by other of the transceivers, and an alarm signal is produced by a transceiver in response to receipt of a transmission whose signal strength is stronger than any other transmission signal strength to which it has been compared. The alarm signal may include a code identifying both the activated movable transmitter and the transceiver producing the alarm signal.

Abstract: An intruder detection system includes a self-supervision feature which, on the basis of detecting authorized pedestrian traffic within a region under surveillance, alerts the system user of potentially faulty system components. Such system comprises a programmable timer which is repeatedly reset to a programmed maximum time interval by each occurence of an alarm-producing event, such as a disturbance of standing microwaves and/or a slight increase in ambient temperature in a region under surveillance. During "disarm" periods when the system alarm is intentionally deactivated to enable use of the protected region without the production of any alarm signals, each occurence of an alarm input to the system alarm (as produced by authorized traffic within the protected region) is used to repeatedly reset the timer to its preselected time interval (e.g., 1,4,8 or 16 days).

Abstract: A multizone intruder detection system comprises a supervisory circuit for verifying, while the system is disarmed, that each of a plurality of intrusion sensors is, indeed, functional. The supervisory circuit inhibits rearming of a disarmed system until it determines that each sensor has successfully operated within a relatively brief time interval just prior to the time an attempt is made to arm the system. A timing circuit, activated by a preliminary arm signal, operates to establish a time window (e.g. 10 minutes) within which the operability of each sensor must be verified (i.e. walk-tested) as a precondition to system arming. Preferably, the timing circuit is reset by each sensor alarm output, whereby the system user is given the full time window to walk-test each sensor. By virtue of the invention, sensor sabotage in a disarmed system can be mitigated.