Abstract: A synthetic impedance telecommunication line driver has no electrical energy-dissipating elements in series with its output, and synthesizes its output impedance in accordance with current fed back from an output current (mirror) sensing circuit. This allows the driver to realize substantially reduced power requirements for driving a telecommunication line, such as, but not limited to a DSX-1 line. The driver includes an operational amplifier having a first polarity input coupled through an input resistor to an input port, to which a signal voltage to applied to an output port is coupled. A second polarity input of the amplifier is coupled to a reference voltage. A feedback resistor is coupled between the amplifier output and its inverting input. An output current-dependent current source, such as a current mirror coupled in circuit with the output node, generates a current as a small fraction k of the output current.

Abstract: A synthetic impedance telecommunication line driver has no electrical energy-dissipating elements in series with its output, and synthesizes its output impedance in accordance with current fed back from an output current (mirror) sensing circuit. This allows the driver to realize substantially reduced power requirements for driving a telecommunication line, such as, but not limited to a DSX-1 line. The driver includes an operational amplifier having a first polarity input coupled through an input resistor to an input port, to which a signal voltage to applied to an output port is coupled. A second polarity input of the amplifier is coupled to a reference voltage. A feedback resistor is coupled between the amplifier output and its inverting input. An output current-dependent current source, such as a current mirror coupled in circuit with the output node, generates a current as a small fraction k of the output current.

Abstract: A line driver with positive feedback reduces the output signal amplitude excursion required for driving a communication line, and enables the driver's output impedance to be synthesized using a reduced component value, thereby achieving a reduction in power loss through the output resistor, while simultaneously matching the effective electrical value of the driver's output impedance to the line. The line driver includes an operational amplifier having differential polarity inputs and an output. An output resistor, whose value is a fraction of the line impedance, is coupled between the amplifier output and an output node coupled to the line. A negative feedback resistor is coupled between the amplifier output and an inverting input. A further resistor is coupled between the amplifier output and a non-inverting input.

Abstract: A system and method are provided wherein binary communications signals are received, and sequences of values of like types of these, such as positive ones, positive zeroes, negative ones, and negative zeroes, are observed. Responsive to a sequence of like-type signals, a reference potential is driven generally in the direction of value of these signals, and most responsively in the direction of the greatest signal degradation. A reference potential for each type is then stored, and the one of these having the most degraded amplitude is selected, and an indication of the percentile of its degradation is provided.

Abstract: A telecommunications line test system wherein a digital telecommunications network is electronically sectionalized via at least one master test unit in combination with at least one remotely addressable field loopback unit whereby the defective line section is isolated by progressively looping back test data as transmitted from a master test unit. Each field loopback unit, when properly addressed, will loopback to both the near side and the far side of the line so as to enable a given loopback unit to be reset (inactivated) from either side of the line.

Abstract: A sample of a normal data communications stream producing an error is thereafter employed via a loop back arrangement as a test sample data stream for error detection.