US4737771A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Security system with interference detection
Assignee: Emhart Industries Inc
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Filing: 1986-07-23
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Granted: 1988-04-12
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Expires: 2006-07-23
Abstract
Abstract A security system having one or more sending units for transmitting an electromagnetic signal representative of a condition such as fire, smoke, intrusion, battery condition, an emergency or other condition to a central receiving unit. Upon reception of an electromagnetic signal, the receiving unit provides an electromagnetic carrier detect signal to a microprocessor. A software timer within the microprocessor keeps track of the time over which the carrier is detected. If the carrier detection continues for a time longer than about 20 seconds, then a jamming indication signal is provided to one or more outputs. While the system is being jammed, alarms are ignored thus avoiding false alarms due to interference.
Inventors
- 👤 Ronald J. Coash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:50
CPC Classifications
H; H04; H04K; H04K3/00; H04K3/80; H04K3/88; G; G08; G08B; G08B25/00; G08B25/01; G08B25/10; G08B29/00; G08B29/18; H04K3/20; H04K3/22; H04K3/222; G08B25/007
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
79 words
A security system comprising: sensor means for sensing a condition and producing a data signal representative of the condition; transmitter means for transmitting an electromagnetic signal modulated by said data signal; receiver means for receiving said electromagnetic signal and providing a received data signal; interference detection means for detecting interference with said electromagnetic signal and producing a control signal; and output means responsive to said received data signal and said control signal for providing an indication of said condition.
Claim 2
Dependent Claim
79 words
A security system comprising: sensor means for sensing a condition and producing a data signal representative of the condition; transmitter means for transmitting an electromagnetic signal modulated by said data signal; receiver means for receiving said electromagnetic signal and providing a received data signal; interference detection means for detecting interference with said electromagnetic signal and producing a control signal; and output means responsive to said received data signal and said control signal for providing an indication of said condition.
Claim 3
Dependent Claim
26 words
A security system as in claim 1 wherein said output means includes a means for providing an indication that interference with said electromagnetic signal is present.
Claim 4
Dependent Claim
31 words
A security system as in claim 1 wherein said interference detection means comprises a means for determining that a signal has been received by said receiver continuously for a predetermined time.
Claim 5
Dependent Claim
57 words
A security system as in claim 1 wherein said interference detection means includes a means for producing a carrier detect signal indicative that an electromagnetic wave is being received by said receiver, timing means for producing a timing signal, and a means responsive to said carrier detect signal and said timing signal for producing said control signal.
Claim 6
Dependent Claim
25 words
A security system as in claim 2 wherein said output means includes a means for indicating that said interference has occurred at a prior time.
Claim 7
Dependent Claim
28 words
A security system as in claim 5 wherein said means for indicating that said interference has occurred comprises a means for recording the time when said interference occurred.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-04-12 | 1991-10-12 | 1992-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-12 | 1995-10-12 | 1996-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-12 | 1999-10-12 | 2000-04-12 | $7700.00 | Window Closed / Lapsed |