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Device for detectinbg telephone line seizure

A technology of telephone line and measurement circuit, which is applied in the direction of telephone communication, electrical components, line monitoring circuit, etc., and can solve the problem of large extra production cost and so on

Inactive Publication Date: 2004-07-14
THOMSON LICENSING SA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

One way around this drawback is to choose an optocoupler with a precise conversion factor, which incurs a significant additional production cost

Method used

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  • Device for detectinbg telephone line seizure
  • Device for detectinbg telephone line seizure
  • Device for detectinbg telephone line seizure

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0013] Such as figure 1 As shown, the device according to the invention comprises: a capacitor C, with a voltage U L connected to the terminal of the telephone line; and two optocouplers OC arranged head to tail 1 、OC 2 , the two optocouplers are connected in series with the terminals of the telephone line. These two optocouplers form the electrically protected interface between the telephone line and the circuit that measures the line voltage. In the diagram, the telephone line includes: A resistor R as load resistance 1 ; and a discharge circuit I that is connected to the line and the capacitor so that the capacitor C D flow through the discharge resistor R D . Resistance R 1 is high impedance such that through resistor R 1 The current charging the capacitor C is very low so as not to disturb the lines. Discharge resistance R D for low impedance, if required, use the first optocoupler to lower OC 1 collector voltage of the transistor. In certain cases, the resist...

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PUM

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Abstract

The device for detecting telephone line seizure performs a measurement of voltage (UL) of the telephone line across a first and a second optocoupler (OC1, OC2) connected in series to the telephone line and arranged head-to-tail. The first optocoupler (OC1) makes it possible to discharge a capacitor (C) connected to the telephone line, the second optocoupler (OC2) converts the discharge current (ID) into an image current (ID') in a measurement circuit (S). This device comprises means ensuring negative feedback of the second optocoupler (OC2) to the first optocoupler (OC1). With this layout, the influence of the transfer coefficients of the optocouplers on the voltage measurement is decreased, so as to increase the accuracy of measurement.

Description

technical field [0001] The invention relates to a device for detecting a telephone line seizure, the voltage of which is measured by means of first and second optocouplers arranged in series and end to end with said telephone line, The first optocoupler discharges a capacitor connected to the telephone line, and the second optocoupler converts the discharge current into a mirror current in the measurement circuit. Background technique [0002] More specifically, the present invention is applied to a telephone device or terminal capable of conducting telephone calls in an anonymous manner. For example, the present invention can be integrated into a cable or satellite television network subscription module that is installed in a user's home to connect to a television receiver, to a cable or satellite network, and to a telephone line. With such a module, a user can specifically order a movie of his choice by selecting from a menu offered by a particular channel of the cable ne...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04M1/00H04M1/82
CPCH04M1/82H04M3/22
Inventor 托马斯·勒加雷克
Owner THOMSON LICENSING SA