Failure alarm for a transmission line communications system
First Claim
1. In a transmission line communications system having at least one means connected to the transmission line for transmitting continuous information carrier signals and at least one means connected to the transmission line for receiving the information carrier signals and an alarm means responsive to the power level of the carrier signals, the alarm means comprising:
- means responsive to the received carrier signals for generating a signal representing the power level of the received carrier signals;
means responsive to said power level signal for generating an alarm signal when the power level of the received carrier signals falls below a predetermined magnitude;
means responsive to said alarm signal for generating an alarm condition signal after a predetermined time delay; and
means responsive to said alarm condition signal for generating an alarm idle signal, the receiving means responding to said alarm idle signal to release the receiving means from receiving the carrier signals.
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Accused Products
Abstract
A power failure alarm circuit for a transmission line communications system such as a telephone system having means for transmitting and receiving carrier signals connected to a trunk line at an end central office. The alarm circuit monitors the power level of a selected number of the different frequency carriers received on the trunk line and generates an alarm condition signal when the combined power levels fall below a predetermined magnitude. The carrier signal receiving means responds to the alarm condition signal to release the subscribers. After a predetermined delay, the alarm circuit generates an alarm busy signal and the receiving means responds by forcing the trunk lines busy to prevent seizure by new callers. The alarm circuit also monitors the level of power being sent to signal repeaters connected to the trunk line and generates an enable signal when said power is lost. The transmitting means responds to the enable signal by pulsing the carrier signals to signal another end central office of the alarm condition.
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Citations
21 Claims
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1. In a transmission line communications system having at least one means connected to the transmission line for transmitting continuous information carrier signals and at least one means connected to the transmission line for receiving the information carrier signals and an alarm means responsive to the power level of the carrier signals, the alarm means comprising:
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means responsive to the received carrier signals for generating a signal representing the power level of the received carrier signals; means responsive to said power level signal for generating an alarm signal when the power level of the received carrier signals falls below a predetermined magnitude; means responsive to said alarm signal for generating an alarm condition signal after a predetermined time delay; and means responsive to said alarm condition signal for generating an alarm idle signal, the receiving means responding to said alarm idle signal to release the receiving means from receiving the carrier signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In a telephone system having a trunk line connected between two end central offices, each end central office having means for transmitting and receiving continuous information carrier signals over the trunk line, an alarm means comprising:
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means responsive to the carrier signals received at one of the end central offices for generating a signal representing the power level of at least one of the received carrier signals; means responsive to said power level signal for generating an alarm condition signal when the power level of said one carrier signal falls below a predetermined magnitude; and means responsive to said alarm condition signal for generating an alarm idle signal, the receiving means at said one end central office being responsive to said alarm idle signal for releasing the carrier signals. - View Dependent Claims (12, 13, 14, 15, 16)
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17. In a telephone system having a trunk line connected between two end central offices, each end central office having means for transmitting and receiving continuous information carrier signals over the trunk line, an alarm means comprising:
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means for detecting an alarm condition at one of the end central offices and generating an alarm signal; means responsive to said alarm signal for generating an enable signal and an alarm condition signal after a predetermined time delay; and means responsive to said alarm condition signal for generating an alarm idle signal whereby the receiving means at said one end central office is responsive to said alarm idle signal for ending the reception of the carrier signals and the transmitting means is responsive to said enable signal for signaling the other end office of the alarm condition. - View Dependent Claims (18)
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19. In a telephone system having a trunk line connected between two end central offices, each end central office having means for transmitting and receiving continuous information carrier signals over the trunk line, an alarm means comprising:
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means for detecting an alarm condition at one of the end control offices and generating an alarm signal; means responsive to said alarm signal for generating an enable signal and an alarm condition signal after a predetermined time delay; and means responsive to said alarm condition signal for generating an alarm idle signal whereby the receiving means at said one end central office is responsive to said alarm idle signal for ending the reception of the carrier signals and the transmitting means at said one end central office is responsive to said enable signal for pulsing the carrier signals to signal an alarm condition to the other end central office. - View Dependent Claims (20, 21)
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Specification