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US 5,850,178 AGranted
Alarm system having synchronizing pulse generator and synchronizing pulse missing detector
AssigneePittway Corporation
InventorsSimon Ha, Andy Chud
Life of this patent
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Abstract
A pulse detection circuit to be used in combination with a generator of a train of synchronizing pulses. The detection circuitry remains in a first, inactive state in the presence of an ongoing sequence of synchronization pulses. In the event of a detected absence of synchronizing pulses for a predetermined period of time, the detection circuitry changes state and generates an electrical output signal indicative of one or more missing synchronizing pulses. The detection circuitry can incorporate either digital or analog timing circuitry.
Claims4
An alarm system comprising:
- a control unit;
- a plurality of ambient condition detectors coupled to the control unit;
- a plurality of alarm indicating output devices;
- a pulse generator coupled to the control unit and to the output devices wherein the generator, at least during an alarm condition, generates a train of synchronizing pulses for at least some of the output devices;
- and
- circuitry coupled to the control unit and to the output devices for detecting an absence of the synchronizing pulses and for coupling an electrical signal indicative thereof to the control unit.
3 more elements
Dependencies are inferred from the claim text.