US3930246A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical alarm system
Assignee: Individual
•
Filing: 1975-01-13
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Granted: 1975-12-30
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Expires: 1995-01-13
Abstract
Abstract An electrical alarm system for monitoring from a central monitoring station various conditions including sounds at one or more remote protected stations is disclosed. The system utilizes conventional signal communications media, including but not limited to telephone lines, T.V. cables, and microwave for the transfer of signals between the monitoring station and the remote stations. The central station includes means for periodically producing and transmitting an audio frequency line integrity test signal to the remote station. The remote station includes means to receive the periodic audio frequency test signals and in response thereto has means to produce one or more different frequency response signals indicative of specific conditions at the remote station. The response signals are returned to the central station, provided the interconnecting circuits are complete, where they are detected by one or more tone detectors. The detected response signals at the central station stop the transmission of test signals until another test cycle is initiated. The presence of the response signals at the central station verifies the line integrity of the system between the central and remote stations. The absence of a response signal at the central station after a predetermined time interval indicates line failure and an alarm is actuated. The ''''on'''' - ''''off'''' status of the monitor at the remote station is tested and differentiated from the line integrity test by means at the remote station for producing a different frequency response signal when the monitor is ''''off'''' from that produced when the monitor is ''''on.'''' The response signals indicative of the ''''on'''' or ''''off'''' status of the remote station are detected by separate detectors at the central station and, depending upon which signal is received, control a status register and indicator. A special circuit at the remote station will block the transmission of any response signals to the central station when microphone leads in a sound monitor are cut. The absence of response signals at the central station alerts an operator at the central station to a failure in the system. A fire sensor and one or more sensors of emergency conditions at the remote station cause the generation of different audio frequency signals indicative of specific abnormal conditions which are sensed. These frequencies are transmitted to and detected at the central station to cause alarms indicative of the specific abnormal conditions occurring at the remote station to be actuated.
Inventors
- 👤 Scott V Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 22:23
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/04
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
399 words
In a monitoring system for monitoring from a central station at least one condition occurring in at least one remote station, said system having communication means for transfer of electrical signals between said central and remote stations, coupling means at said central and remote stations for coupling electrical signals between said communication means and said central and remote stations respectively, said coupling means having transmit and receive ports, an improved system for testing the integrity of said monitoring system comprising means at the central station for generating periodic test pulses, test oscillator means for generating a first frequency test signal, oscillator control means for turning said oscillator means on and off so that the oscillator means will oscillate while on and cease to oscillate while off, said oscillator control means being responsive to pulses from said test pulse generating means to turn said oscillator means on, means for conducting said first frequency test signal to the transmit port of said coupling means at said central station whereby said test signal is coupled to said communication means and conveyed to the receive port of said remote station, means at said remote station responsive to said test signal to produce a second frequency signal different from said test signal, circuit means for conducting said second frequency signal to the transmit port of said coupling means at said remote station whereby said second frequency signal is coupled to said communication means and conveyed to the receive port of said central station, a first detector means responsive to said second frequency signal for producing a verify signal when said second frequency signal is detected, said control means being responsive to said verify signal for turning said oscillator means off, an alarm for alerting an operator whenever a verify signal fails to be produced within a predetermined time period after each test pulse, said alarm having means for actuating said alarm in response to a test pulse signal after a time delay equal to said predetermined time period and means responsive to said verify signal for blocking the actuation of said alarm when the verify signal is received within said predetermined time period, said predetermined time period being equal to at least the propagation delay time within the testing system which is measured from the time each test pulse is generated until a second frequency signal can normally be detected by said detector means.
Claim 2
Dependent Claim
399 words
In a monitoring system for monitoring from a central station at least one condition occurring in at least one remote station, said system having communication means for transfer of electrical signals between said central and remote stations, coupling means at said central and remote stations for coupling electrical signals between said communication means and said central and remote stations respectively, said coupling means having transmit and receive ports, an improved system for testing the integrity of said monitoring system comprising means at the central station for generating periodic test pulses, test oscillator means for generating a first frequency test signal, oscillator control means for turning said oscillator means on and off so that the oscillator means will oscillate while on and cease to oscillate while off, said oscillator control means being responsive to pulses from said test pulse generating means to turn said oscillator means on, means for conducting said first frequency test signal to the transmit port of said coupling means at said central station whereby said test signal is coupled to said communication means and conveyed to the receive port of said remote station, means at said remote station responsive to said test signal to produce a second frequency signal different from said test signal, circuit means for conducting said second frequency signal to the transmit port of said coupling means at said remote station whereby said second frequency signal is coupled to said communication means and conveyed to the receive port of said central station, a first detector means responsive to said second frequency signal for producing a verify signal when said second frequency signal is detected, said control means being responsive to said verify signal for turning said oscillator means off, an alarm for alerting an operator whenever a verify signal fails to be produced within a predetermined time period after each test pulse, said alarm having means for actuating said alarm in response to a test pulse signal after a time delay equal to said predetermined time period and means responsive to said verify signal for blocking the actuation of said alarm when the verify signal is received within said predetermined time period, said predetermined time period being equal to at least the propagation delay time within the testing system which is measured from the time each test pulse is generated until a second frequency signal can normally be detected by said detector means.
Claim 3
Dependent Claim
96 words
The system according to claim 1 wherein said monitoring system has audio monitoring means at said remote station which includes microphone transducer means for converting sounds within said remote station into audio electric signals, means for amplifying said audio electric signal and means for conducting said audio electric signals to said transmit port of said coupling means at said remote station whereby said audio electric signals are conveyed to the receive port of said coupling means at said central station, and audio transducing means at the central station for transducing said audio electric signals into sound.
Claim 4
Dependent Claim
24 words
The system according to claim 2 together with alarm means responsive to said audio electric signals above a preset threshold for alerting an operator.
Claim 5
Dependent Claim
44 words
The system according to claim 2 together with blocking means for blocking audio electric signals from said audio transducing means while said first frequency test signal is being produced and while said second frequency response signal is being detected by said first detector means.
Claim 6
Dependent Claim
92 words
The system according to claim 4 wherein said blocking means includes a normally open control gate in circuit between said central station receive port and said audio transducing means, and an OR gate for closing said control gate, said OR gate having a pair of input terminalS connected to said first detector means and said oscillator control means respectively, said OR gate being responsive to signals from either said oscillator control means or said first detector means to close said control gate and thereby block audio signals from said audio transducing means.
Claim 7
Dependent Claim
186 words
The system according to claim 2 wherein said monitoring system includes a power supply means for energizing said audio monitoring means at said remote station and a power switch for turning said power supply on and off, a two position status switch operatively coordinated with said power switch to indicate the on or off status of said power switch when in the one or the other of said two positions, means for producing a third frequency signal different from said first and second frequency signals, said status switch when in said one position connecting the second frequency signal producing means to said transmit port of said coupling means at said remote station and when in said other position connecting the third frequency signal producing means to said latter couling means, a second detector means at said central station for detecting said third frequency signal and producing an off status signal, and status indicator means alternatively responsive to said verify signal from said first detector means and to said off status signal from said second detector to indicate the on and off status of said power switch.
Claim 8
Dependent Claim
66 words
The system according to claim 6 together with a pair of normally closed detector output gates connected respectively between said first and second detectors on their one side and said status indicator means on their other side, said detector gates each having means responsive to said oscillator control means for opening said detector gates while said oscillator control means operates to turn said oscillator means on.
Claim 9
Dependent Claim
51 words
The system according to claim 7 together with an OR gate responsive to either of said verify signal or said off status signal for producing an output reset signal for resetting said oscillator control means and thereby turning off said oscillator means until another first frequency signal test pulse is received.
Claim 10
Dependent Claim
192 words
The system according to claim 2 wherein said microphone transducer means has a relatively low electrical resistance path for direct current between a pair of output terminals, a conductor lead connecting one of said output terminals to said amplifier means, a source of direct current and a resistor having a resistance which is high relative to said microphone resistance path connected between said other terminal and a point on said lead near the amplifier means, means responsive to the cutting of said conductor lead anywhere between said microphone and said point for blocking the response of said second frequency signal producing means to said first frequency test signal including a normally open gate connected in series circuit between said remote station receive port and said second frequency signal producing means, said gate having a control input terminal and circuit means connecting said control input terminal to said flexible conductor adjacent said point, said circuit means being responsive to a change in d.c. voltage at said point when said microphone conductor lead is cut to close said gate and prevent the response of said second frequency signal producing means to said test signal.
Claim 11
Dependent Claim
44 words
The system according to claim 9 wherein said circuit means includes at least one asymmetrical device for preventing current flow in the direction from said gate control input terminal to said point on said conductor lead while permitting current flow in the opposite direction.
Claim 12
Dependent Claim
235 words
The monitoring system according to claim 2 wherein said means at said remote station responsive to said test signal to produce a second frequency signal different from said test signal includes a two-tone generator means which is operable in response to control signals to produce alternatively two-tones which differ from each other and from said firSt signal frequency, a control logic means for producing control signals which actuate said tone generator to produce one or the other of said two tones, a test tone detector for detecting said first frequency test signal and producing an output signal for triggering said control logic to actuate said two-tone generator means to generate either one of two tones depending on the position of a status switch, a two position status switch for indicating the on or off status of said monitoring system at said remote station, said status switch in the off position producing a signal which triggers said control logic to respond to said tone detector output signal to cause said two-tone generator to produce the one of said two tones indicative of the off position of said status switch, the status switch in the on position producing a signal which triggers said control logic to respond to said tone detector output to cause said two tone generator to produce the other of said two tones which is indicative of the on position of said status switch.
Claim 13
Dependent Claim
114 words
The apparatus according to claim 11 wherein said first tone detector means is a two-tone detector which operates to distinguish between the one and the other of the two tones produced by said two-tone generator and produce alternatively one of two status output signals, depending on which of said two tones is detected, and a status indicator means at said central station responsive alternatively to the two status output signals to indicate the on or off status of said monitoring system at the remote station, each of said two status output signals corresponding to said verify signal, and said control means being responsive to the status output signals for turning said oscillator means off.
Claim 14
Dependent Claim
173 words
The system according to claim 12 together with means for sensing a fire and producing a control signal indicative of said fire, means for sensing an emergency condition other than said fire and producing a control signal indicative of said emergency condition, said control logic being responsive to said fire control signal to trigger said two-tone generator to produce one of said two tones and being responsive to said emergency control signal to trigger said two-tone generator to produce the other of said two tones, a fire indicator means at said central station, an emergency indicator means at said central station and an alarm tone detector means at said central station for distinguishing between the two tones produced by said two-tone generator and producing in response to the one tone a fire alarm signal, and in response to the other tone an emergency signal, said fire indicator means being responsive to said fire alarm signal for indicating a fire, and said emergency indicator being responsive to said emergency signal for indicating an emergency.
References Cited (Backward Citations)
US3473055A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |