Siemens Aktiengesellschaft

Gerald Wallnberger

Herbert Zojer

Franz Dielacher

Karl Formanek

A circuit configuration for the generation of a line terminating impedance includes a two-wire to four-wire converter having a transfer function. An analog impedance network has a transfer function and input and output sides being connected through the two-wire to four-wire converter to a line. A digital impedance network has a transfer function and is connected in parallel with the analog impedance network through an analog-digital converter unit and a digital-analog converter unit. A real portion of a sum of the transfer function of the analog impedance network and a product of the transfer functions of the analog-digital converter unit, the digital impedance network and the digital-analog converter unit, multiplied by the transfer function of the two-wire to four-wire converter, is greater than -1.

Circuit configuration for the generation of a line terminating impedance

In a method and configuration for forming a line termination at two line terminals of a telephone line, alternating signals are separated from direct signals applied to line terminals, referred to a reference variable and added to a transmission signal from a transmission terminal to form a resultant actual-value signal. The resultant actual-value signal is compared with a reference signal at a gain-controlled amplifier. The reference signal is formed with an impedance transmission function corresponding to a given termination impedance by weighting the alternating signal at one of the line terminals being connected to a current sensor resistor. A current between the line terminals is determined with a control transistor associated with the current sensor resistor. The control transistor is controlled with the gain-controlled amplifier.

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Villach, Austria

Gerald Wallnberger