US4415885A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intrusion detector
Assignee: Stellar Systems Inc
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Filing: 1981-05-21
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Granted: 1983-11-15
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Expires: 2001-05-21
Abstract
Abstract An intrusion detector is provided having transmission and receiving cables wherein the cables are leaky from an RF standpoint so that a portion of the RF energy from the transmission cable escapes and is picked up on the receiving cable. Both sine and cosine signals are detected. The cables can be buried.
Inventors
- 👤 Ronald W. Mongeon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:33
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2491; G08B13/2497
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
174 words
An intrusion alarm system comprising in combination: a. RF generator and means for feeding an unmodulated output from said generator to a leaky transmission line, b. a leaky receiving line roughly paralleling said transmission line and leading to a receiver, c. means for feeding a DC voltage through said receiving line, d. rectifying means for developing a DC voltage from the RF on said transmission line, e. first alarm means comprising a comparator for comparing the DC voltages from (c) and (d) and sounding an alarm if the voltages differ substantially from a target value, f. second alarm means comprising: (i) means for feeding the RF output from the receiving line to an inphase detector, (ii) means for shifting the phase of the RF output 90° and feeding the phase shifted output to a quadrature detector, (iii) feeding the output of the inphase and quadrature detectors to an absolute value detector which acts as an OR gate whereby (iv) said second alarm means actuated by a perturbation in either the inphase or quadrature detectors.
Claim 2
Dependent Claim
174 words
An intrusion alarm system comprising in combination: a. RF generator and means for feeding an unmodulated output from said generator to a leaky transmission line, b. a leaky receiving line roughly paralleling said transmission line and leading to a receiver, c. means for feeding a DC voltage through said receiving line, d. rectifying means for developing a DC voltage from the RF on said transmission line, e. first alarm means comprising a comparator for comparing the DC voltages from (c) and (d) and sounding an alarm if the voltages differ substantially from a target value, f. second alarm means comprising: (i) means for feeding the RF output from the receiving line to an inphase detector, (ii) means for shifting the phase of the RF output 90° and feeding the phase shifted output to a quadrature detector, (iii) feeding the output of the inphase and quadrature detectors to an absolute value detector which acts as an OR gate whereby (iv) said second alarm means actuated by a perturbation in either the inphase or quadrature detectors.
Claim 3
Dependent Claim
17 words
The alarm system of claim 1 wherein said transmission and receiving lines are buried in the earth.
Claim 4
Dependent Claim
24 words
The system of claim 2 wherein the lines are spaced from about 40 to 50 inches apart and buried about 4 to 6 inches.
Claim 5
Dependent Claim
19 words
The system of claim 2 wherein the system operates in the VHF range of about 10 to 100 MHz.
Claim 6
Dependent Claim
12 words
The system of claim 4 wherein the frequency is about 60 MHz.
Claim 7
Dependent Claim
40 words
The intrusion alarm of claim 1 wherein said R.F. generator feeds the output into one end of the transmission line and the receiver is connected at the opposite end of the receiving line whereby attenuation in the lines is offset.
Claim 8
Dependent Claim
17 words
The system of claim 1 wherein the cables consist of coaxial cables with only a partial shield.
References Cited (Backward Citations)
US3794992A
Cited
US4091367A
Cited
US4053877A
Cited
US4135185A
Cited
US4207560A
Cited
US4213123A
Cited
US4224607A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-11-14 | 1987-05-16 | 1987-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-14 | 1991-05-16 | 1991-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-14 | 1995-05-16 | 1995-11-15 | $7700.00 | Window Closed / Lapsed |