US 6,661,893 B1 · Telephone loop monitoring and isolation system

Abstract

A telephone loop monitoring and isolation device which can be connected to a wireless telephone subscriber unit providing an interface between an analog or digital central station network and the internal telephone wiring of a subscribers premises. The device is also operable with a cable telephone subscriber unit. The device provides passive real time loop status information as well as loop isolation if the voltage across the loop falls below a predetermined level. When normal loop impedance conditions are restored, the subscriber loop is automatically reconnected to the subscriber telephone unit. The device is effective for examining open circuit and abnormal impedance conditions and provides loop status information to the telephone subscriber. The system of the invention also has an alarm enhancement in that it will provide an alarm status indication to a monitoring center, such as a police department or the like, while still maintaining communication capabilities, even during an existing active telephone communication.

Claims11

Dependent claims

An arrangement for monitoring a premises telephone circuit connected in parallel with an external telephone network, and isolating the premises circuit from the external telephone network upon determining that a fault exists with either the premises circuit or the external network, said arrangement comprising:

a sensing circuit operatively interposed between the premises circuit and the external telephone network that monitors a tip and ring voltage level on the premises circuit and the parallel external telephone network;
an isolation circuit connected to the sensing circuit that disconnects the premises circuit from the external telephone network if the sensing circuit senses that the monitored tip and ring voltage level is outside of a predefined voltage range;
a comparator circuit that separately tests the external telephone network and the premises circuit following disconnection of the premises circuit, to determine whether the fault exists with the external telephone network or the premises circuit, said comparator circuit including:
means for injecting a voltage onto the premises circuit following disconnection of the premises circuit from the external telephone network;
means for measuring an impedance level on the disconnected premises circuit resulting from the injected voltage;
and
means for determining that the fault exists with the premises circuit if the measured impedance level is outside of a predefined impedance range;
and
means connected to the sensing circuit for automatically reconnecting the premises circuit to the external telephone network if the sensing circuit senses that the tip and ring voltage level on the premises circuit and the parallel external telephone network has returned to the predefined voltage range.

6 more elements

A system for controlling interaction between an external telephone network and a premises telephone circuit having a plurality of parallel branches for connecting a plurality of individual communication units, said system comprising:

a premises monitoring device operatively interposed between the premises circuit and the external telephone network, said premises monitoring device including:
a premises/network sensing circuit that simultaneously monitors operating conditions for both the premises circuit and the external telephone network;
a premises isolation circuit connected to the premises/network sensing circuit that disconnects the premises circuit from the external telephone network if the premises/network sensing circuit senses a fault with the premises circuit or the external telephone network;
a comparator circuit that separately tests the premises circuit and the external telephone network to determine whether the fault is with the premises circuit or the external telephone network;
and
means connected to the premises/network sensing circuit for automatically reconnecting the premises circuit to the external telephone network if the premises/network sensing circuit senses that the premises circuit and the external telephone network are operating normally;
and
a plurality of branch monitoring devices, each of said branch monitoring devices being connected to and monitoring conditions on a different parallel branch of the premises circuit, each of said branch monitoring devices including:
a branch sensing circuit operative to detect a fault with the monitored branch;
and
a branch isolation circuit connected to the branch sensing circuit that disconnects the monitored branch from the premises circuit when the branch sensing circuit detects the branch fault, and sustains normal operating conditions on the disconnected monitored branch so that the remaining parallel branches of the premises telephone circuit remain operational after the disconnected monitored branch is disconnected.

8 more elements

Dependencies are inferred from the claim text.

Telephone loop monitoring and isolation system

Life of this patent

Telephone loop monitoring and isolation system

Life of this patent

Abstract

Claims11