Telephonic communications – Subscriber line or transmission line interface
Reexamination Certificate
1999-08-18
2003-12-09
Tieu, Binh (Department: 2643)
Telephonic communications
Subscriber line or transmission line interface
C379S002000, C379S093050, C379S177000
Reexamination Certificate
active
06661893
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to certain new and useful improvements in telephone line monitoring apparatus and, more particularly, to a device which is capable of monitoring a wireless subscriber unit which provides an interface between an analog or digital network and a subscriber's premises telephone wiring and isolating of the phone loop when the voltage falls below a predetermined level.
2. Brief Description of the Related Art
Wireless subscriber telephone units are now becoming quite prevalent throughout much of the world. These wireless telephone units include wireless transmitter and a receiver capable of communicating through a subscriber network to a base station located at a cell site. In fact, in many third world countries, wireless telephone subscriber units are becoming more prevalent then in the United States. The subscriber unit also provides an interface to the subscriber premises telephone wiring.
In many cases, there are still telephones which are hard wired to a central station for operation in many countries, as in much of the United States. The wireless telephone units by definition do not operate through a hard wire circuit. Although cordless telephones do operate through a hard wired circuit, they are considered to be hard wired telephone systems and not subject matter for use in the present invention. In addition, many subscriber telephone units are operable with cable subscriber units and, here again, the mode of operation is similar to that of an analog or a digital network.
In the event of an interruption in telephone service, the user of the wireless telephone system is frequently unable to locate the source of the problem. That source may be a malfunctioning telephone unit or it may well be a short or an open circuit in the wiring between the telephone unit and the subscriber unit. Further, a short could exist between the monitoring device and the telephone. Abnormal loop conditions within the subscriber's premises may exist, in effect, between the subscriber unit and the monitor or otherwise between the monitoring unit and the telephone unit. It would be desirable to provide a device which allows for monitoring of a wireless telephone system.
In many cases, the wireless communication to the subscriber's premises may be digital and in many cases it may be a analog. It would therefore be desirable to provide a device which is capable of operating with both digital and analog units to monitor same and which device could also provide for isolation. While a network operator or repair service may be able to determine if a fault has occurred because of the wireless connection, a monitoring device is nevertheless required to determine if there was a fault within the subscriber's premises.
The need for monitoring a telephone loop is also becoming important in those cases where gates and other security accesses are connected directly through a telephone system. It is important to insure that a breach of security does not result by purposely cutting a telephone line or otherwise attempting to interfere with a telephone network. Thus, it would be important to enable monitoring of a system, even where a breach in that system has resulted.
Although there are no known prior art teachings of a solution to the aforementioned deficiencies and shortcomings, such as those disclosed herein, U.S. Pat. No. 4,390,750 to Bartelink (Bartelink), U.S. Pat. No. 4,446,340 to Fryer (Fryer), and U.S. Pat. No. 4,417,137 to Rosenfeld, et. al (Rosenfeld) discuss subject matter that bears some relation to matters discussed herein. Bartelink discloses a remote supervisory system for monitoring the status of a subscriber's premises over existing telephone circuits from the central office. Auxiliary equipment at the subscriber's premises is coupled to the subscriber's telephone circuit and includes sensors which monitor the condition of the premises. If an abnormal condition is sensed, the auxiliary equipment notifies the central office which may further notify an action center at that central office of the subscriber's identity and nature of the alarm.
Fryer discloses a loopback circuit for testing a telephone line between the central office and a subscriber's equipment. The loopback circuit is located at the subscriber's end of the line and is powered by the normal central office power source. Fryer injects a signal from the central office to actively test the telephone line. Thus, Fryer does not provide a stand alone capability, or a passive capability to monitor the subscriber's premises and report alarm conditions without a wire line connection to the central office.
Rosenfeld discloses an apparatus for monitoring the hook status of a remote telephone. Rosenfeld introduces a disturbance voltage signal onto the subscriber loop from the central office, and then monitors variations in impedance in the subscriber loop. Thus, Rosenfeld does not provide a stand alone capability, or a passive capability to monitor the subscriber's premises and report alarm conditions without a wire line connection to the central office.
With any existing wireless telephone system, there is presently on-premise monitoring with a wireless telephone system and an alarm circuit arrangement used in combination therewith. However, where an alarm would occur with an existing alarm apparatus, it is necessary to isolate the telephone wiring of the premises from the alarm circuit, particularly as connected through tip ring conductors, so that the alarm has a priority of use in the communication path to the telephone network. If this is not achieved, an initiation of an alarm signal to a central station or other monitoring facility, such as a police department, will not be enabled. Thus, there is a need as well for a system which will provide the capability of communicating an alarm status, even during an existing telephone call in the premises.
OBJECTS OF THE INVENTION
It is, therefore, one of the primary objects of the present invention to provide a subscriber premises telephone loop monitoring and isolation device which can be installed both internal to or as an adjunct to a wireless subscriber telephone unit.
It is another object of the present invention to provide a subscriber premises telephone loop monitoring and isolation device which is capable of providing an interface between both an analog telephone wireless network and a subscriber premises telephone wiring system.
It is a further object of the present invention to provide a subscriber premises telephone loop monitoring and isolation device of the type stated which is also effective in operating with a cable or wireless subscriber unit and providing a similar mode of operation therefor.
It is an additional object of the present invention to provide a telephone loop monitoring and isolation device of the type stated which provides passive and real time loop status information to a subscriber unit, as well as loop isolation if the voltage across the loop falls below a predetermined value.
It is another object of the present invention to provide a monitoring and isolation device for use on the subscriber's premises, of the type stated, which will automatically provide a loop-cut through between the telephone unit and the subscriber unit even if a power failure occurs during an active telephone communication.
It is also an object of the present invention to provide a telephone loop monitoring and isolation device of the type stated which is capable of automatically restoring normal telephone loop operation when the impedance conditions are restored to a proper level and the subscriber's premises loop is automatically reconnected to the subscriber unit.
It is still another object of the present invention to provide a telephone,loop monitoring and isolation device of the type stated in which loop status information can be provided directly to a subscriber via the telephone loop monitoring and isolation device.
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Gerlach Richard K.
Vaughn Kenneth
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