Teltrend, Inc.

Rockwell International Corporation

Bruce R Miller

Frank X Garcia

Ian A Schorr

Gregory P Pucci

John P Dorth

An automatic loss compensation for use in a two to four wire hybrid converter in a telephone system. Many hybrid converters provide a substantially fixed gain for receive signals that are provided to the customer loop telephone line and for transmit signals that are provided to the digital carrier transmission line. The compensation circuit includes a measurement circuit, controller, and receive and transmit amplifier. The measurement circuit determines the length of the customer loop telephone line and provides a length signal. The controller receives the length signal and categorizes the length as being within one of a plurality of segments. The controller appropriately varies the amplification and phase of the receive signal, which is then combined with an inverted transmit signal, in order to substantially reduce reflected signals from the transmission line and transmission line termination.

Remote terminal channel unit for telephone transmission lines

A two to four wire hybrid converter for use in a telephone system that allows other telephone equipment, such as a caller identification device, to more readily decipher signals. The converter controls noise by using a digital to analog converter, hybrid circuit, interface circuit, and controller. The digital to analog converter accepts a receive digital data signal from a transmission line and converts it to a receive analog signal. The hybrid circuit accepts the receive analog signal and provides it to the customer telephone line, as well as accepting a transmit telephone analog signal from the customer telephone line. Such transmit telephone analog signals are then converted to digital signals and provided to the carrier transmission lines. The hybrid circuit includes an inverter, variable amplifiers, and summing circuit. The inverter inverts the transmit telephone analog signal with respect to the receive analog signal. In the preferred embodiment, the summing circuit combines the inverted transmit and receive analog signals. A transmit variable amplifier changes the magnitude of the transmit analog signal provided to the summing circuit. A receive variable amplifier changes the magnitude of the analog signal provided to the customer telephone line. A trans-hybrid variable amplifier changes the magnitude of the receive analog signal to be combined with the inverted transmit analog signal. The controller detects whether or not the telephone has gone off hook. Upon receiving a signal that the telephone has gone off hook, the controller changes the gain of the variable amplifiers.

Trans-hybrid loss compensator for on hook transmission

A compensation circuit for adjusting the gain or loss of a four to two wire hybrid circuit in a telephone system automatically, regardless of the length of the telephone line interconnected to the hybrid circuit. The compensation circuit includes a converter, interface, gate array, and controller. The converter, which includes an amplifier with a variable gain, is connected to a digital carrier transmission line. The converter accepts a digital data signal and converts it to an analog intermediate signal. The interface receives the analog intermediate signal and transmits an analog telephone signal, along a customer loop telephone line, to a telephone. The interface also includes a pulse width modulated power converter for which the pulse width varies according to the length of the telephone line between the compensation circuit and the telephone. The gate array senses the pulse width and responsively provides a measured signal to the controller. The controller receives the measured signal, representing the pulse width, as well as a voltage signal, representing the voltage powering the interface, and responsively adjusts the gain or loss of the gain of the variable amplifier.

Gain or loss compensation circuit for telephone lines

A fail safe voice system and method for digital telephone networks. The system provides for operation of voice telephone equipment at a customer location when a fault occurs at the customer location. The system has a central office with an analog line termination/digital transceiver connected to subscriber loop lines. The customer location has a digital transceiver/analog station set interface connected to the subscriber loop lines and to the voice telephone equipment. In response to a fault at the customer location the voice telephone equipment is connected directly to the subscriber loop lines thereby eliminating the digital transceiver/analog station set interface.

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Aurora, IL, United States of America

Bruce R Miller