US 4,096,362 A · Automatic cable balancing network

Abstract

A hybrid circuit for coupling a bidirectional telephone cable to two unidirectional cables is balanced automatically by employing an adjustable balance network and a control circuit. Optimum adjustment of the balance network is achieved over a frequency band of interest by employing a signal source having one or more frequency components within the frequency band of interest and by generating signals for controlling magnitude and phase components in the balance network. The magnitude control signal is representative of the difference between the absolute magnitudes of signals detected at the bidirectional cable connection to the hybrid and at the balance network connection to the hybrid in the frequency band of interest. Signals for controlling the phase components of the balance network are representative of the difference between the absolute magnitudes of the detected signals modified by a first prescribed weighting function less a component proportional to the phase difference between the detected signals modified by a second prescribed weighting function within the frequency band of interest. The weighting functions are obtained by employing a filter having a prescribed low-pass characteristic. The component values of the filter are determined by the locations of adjustable pole(s) and/or zero(s) within the frequency band. The filter characteristic may be adjusted during the balance process further to optimize the balance network adjustments.

Claims17

Dependent claims

In a transmission network of a type including a 4-port hybrid network adapted for being connected to a transmission path exhibiting a complex impedance at a first port and to an adjustable impedance balance network having a plurality of controllable impedance elements for yielding a driving point impedance at a second port, wherein the improvement comprises:

a signal source for generating a test signal having a plurality of frequency components within a predetermined frequency band and having a first prescribed output impedance, said signal source being adapted to be connected to a third port of said hybrid;
a second prescribed impedance being adapted to be connected to a fourth port of said hybrid;
and
a control circuit connected in circuit relationship with said first and second hybrid ports and being responsive to first and second signals developed at said first and second hybrid ports, respectively, in response to said test signal, said complex impedance of the transmission path and said balance network impedance for generating a plurality of control signals for adjusting said controllable impedance elements of said balance network to yield a driving point impedance to match substantially the complex impedance of said transmission path over said frequency band.

1 more element

a signal source for generating a test signal having at least one frequency component within a predetermined frequency band;
and
a control circuit connected in circuit relationship with said first and second hybrid ports and being responsive to first and second signals developed at said first and second hybrid ports, respectively, in response to said test signal, said complex impedance of the transmission path and said balance network impedance for generating a plurality of control signals for adapting said controllable impedance elements of said balance network to yield a driving point impedance to match substantially the complex impedance of said transmission path, said control circuit including means for generating a magnitude control signal and means for generating at least a first singularity control signal, said at least first singularity control signal generating means generates a signal representative of the integral of the difference between a magnitude component equal to the difference between the absolute magnitudes of said first and second signals modified by a first prescribed weighting function, and a phase component proportionately equal to the difference between the phase of said first signal and said second signal modified by a second prescribed weighting function.

Dependencies are inferred from the claim text.

Automatic cable balancing network

Life of this patent

Automatic cable balancing network

Life of this patent

Abstract

Claims17