Antitheft system
First Claim
1. A method for detecting triggering of an alarm sensor, the method comprising:
- measuring in a first envelope signal a first plurality of time periods during each of which a predetermined number of signal pulses are received;
comparing a duration of each of the first plurality of time periods;
determining if each of the durations for each of the first plurality of time periods are within a predetermined time range;
measuring in a second envelope signal a second plurality of time periods during each of which the predetermined number of pulses are received, if each of the determined durations for each of the first plurality of time periods are within the predetermined time range;
comparing a duration of each of the second plurality of time periods; and
providing an alarm indication if each of the durations for each of the second plurality of time periods are within the predetermined time range.
4 Assignments
0 Petitions
Accused Products
Abstract
The present invention provides a burglar alarm system capable of accurately discriminating an alarm from a disturbance noise approximate to the alarm such as background music, ambient noises, etc. In a burglar alarm system comprising an alarm unit attached to an object to be protected from theft to emit an alarm of a particular frequency and an alarm sensor device for issuing an alarm signal upon sensing an alarm from the alarm unit, the alarm sensor device counts a predetermined number of waveform pulses of a received sound (S2, S5) more than once (S1˜S3, S4˜S6), determines, if it transpires that a differential between counted values falls within a predetermined time range, that the received sound is an alarm and issues an alarm signal (S7).
7 Citations
20 Claims
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1. A method for detecting triggering of an alarm sensor, the method comprising:
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measuring in a first envelope signal a first plurality of time periods during each of which a predetermined number of signal pulses are received; comparing a duration of each of the first plurality of time periods; determining if each of the durations for each of the first plurality of time periods are within a predetermined time range; measuring in a second envelope signal a second plurality of time periods during each of which the predetermined number of pulses are received, if each of the determined durations for each of the first plurality of time periods are within the predetermined time range; comparing a duration of each of the second plurality of time periods; and providing an alarm indication if each of the durations for each of the second plurality of time periods are within the predetermined time range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for detecting an alarm condition of an anti-theft system, the method comprising:
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measuring after a predetermined time period a plurality of time periods during each of which a predetermined number of signal pulses are received; comparing a duration of each of the plurality of time periods; determining if each of the durations for each of the first plurality of time periods are within a predetermined time range; and providing an alarm indication if each of the durations for each of the plurality of time periods are within the predetermined time range. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An anti-theft system comprising:
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an alarm unit configured to emit an alarm signal; an alarm sensor device configured to; detect signal pulses; measure in a first envelope signal a first plurality of time periods during each of which a predetermined number of the signal pulses are received; compare a duration of each of the first plurality of time periods; determine if each of the durations for each of the first plurality of time periods are within a predetermined time range; measure in a second envelope signal a second plurality of time periods during each of which the predetermined number of pulses are received if each of the determined durations for each of the first plurality of time periods are within the predetermined time range; compare a duration of each of the second plurality of time periods; and provide an alarm indication if each of the durations for each of the second plurality of time periods are within the predetermined time range indicating that the signal pulses define an alarm signal emitted from the alarm device. - View Dependent Claims (17, 18, 19, 20)
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Specification