DE2009686A1 - Circuit arrangement for monitoring telecommunication lines, in particular telephone lines - Google Patents

Description

Dipl. Phys. Leo Thul
Patent attorney

7 Stuttgart-3o
Short St. 8

A. Regnier-R. Depreux 12-lo

INTERNATIONAL STANDARD ELECTRIC CORPORATION, NEW YORK

Circuit arrangement for monitoring telecommunication,

in particular telephone lines M.

The invention relates to a circuit arrangement for monitoring a telecommunication line, in particular a telephone line, with the one second, initiated by the subscriber without the aid of the earth line Reason in the exchange should be recognizable.

In electromechanical telecommunication systems, so-called feed elements or connection sets are used to monitor telecommunication lines used while connected. These work with relays, which have undefined response and dropout values than it would be possible to use another character; application for the purpose of a second occasion, e.g. an official application permission to make.

The object of the invention is to provide a circuit arrangement for monitoring a telecommunication line, in particular a telephone line, with which a second line can be used by the subscriber without assistance The cause initiated by the earth line should be recognizable in the exchange and the evaluation of this second This can be done quickly and safely even with very different lengths of subscriber lines. This is according to of the invention achieved in that at the ground

7th January 197o Krü / Kn - / -

009839/1394

- 2 A.Regnier-R.Depreux 12-Io

potential terminal connected supply resistor uiü at the with the supply resistor connected to the work potential terminal or a part of the same each have a Staiers voltage for one associated TraisLstor amplifier can be tapped that the one of both transistor amplifiers has a response threshold value that occurs when the subscriber-controlled loop current reduction is fallen below by means of a switchable in the line loop resistance, and that the Both transistor amplifiers deliver the same output potentials to a logic circuit when they respond.

Such an arrangement also has the advantage that an AJL call can be recognized due to the grounding of a line wire is. If that transistor amplifier is provided with the response threshold which is caused by the voltage drop is controlled by the supply resistor connected to the work potential terminal, this transistor amplifier speaks in the case of wrong Do not call on every leakage resistance between the one line wire and earth, but only on one leakage resistance impermissible quantity that affects the response threshold of the transistor amplifier is turned off. The size of the subscriber in depends on just one response threshold the line loop switchable resistance as well as the size of the smallest, still permissible leakage resistance.

Further advantageous features of the invention are based on a special embodiment of the monitoring arrangement.

The invention will now be explained in more detail using an exemplary embodiment.

The figure shows a circuit arrangement for monitoring a Telephone line a, b, on the one hand a subscriber station 12 on the rest side of a changeover contact and also the

009839/1394

A.Regnier-R.Depreux 12-lo

Series connection of a resistor 18 and the working side this TJmschaltkontakt lies. and on the other hand over

two inductors 11, 14 a transistor circuit is connected. The changeover contact mentioned is through a button 13 intended for the second start is pressed. A transistor 1 connected to wire a is turned on when it closes the Pernspreehleitungsschleife independent of the resistance of this Loop is conductively controlled, while a with the wire b connected Tranlstor 3 is controlled when the loop closes depending on the loop resistance.

When the subscriber station is in the idle state, are '"the TrarELstoren 1.3 * 5 and 6 in the non-conducting state, wherein ■ having the emitter and the base of the transistor 1 and 3, the same potential and wherein at the sampling points 7 * 8 no signal ("0") is pending.

When the handset of the subscriber station is lifted, flows Current in the following circuit:

Earth, feed resistors 9 and Io, choke coil 11, wire a, Station 12, rest side of changeover contact Ij5, wire b, choke coil 14, feed resistor 15, minus.

The voltage drop at the feed resistor 9 causes the through (j control of the TraMstors 1. If now the scanning device A the Points 7.8 sampled, a current can flow through the collector-emitter path of the transistor 5 fHessen, which is connected to the transistor 1 is controlled. At point 7 there is approximately earth potential, which here corresponds to a logical "1".

In the same way, the voltage drop at the supply resistor causes it 15 the activation of the transistor 3. When the scanning device reaches point 8, a current can flow through the collector-emltter path of the transistor 6 which is controlled by the transistor 3 flow. At point 8 there is also earth

009839/1394

A. Regnier-R-Depreux 12-Io

potential, a logical "l". The condition of the communication line, in which the handset is lifted, is accordingly the scanning device by "1" signals at the scanning points 7 * 8, i.e. by the same signals at the transistor amplifier outputs, displayed.

The request for a second occasion is indicated to the scanning device by the signal "1" at the scanning point 7 and by the signal ^tf 0 ^{: f} at the scanning point 8. On such a second occasion, the button 1J> is pressed and the high-resistance resistor 18 is inserted into the line loop instead of the low-resistance station. This lowers the loop current. At point 16, a potential occurs which still leads to transistor 1 being turned on. At point 19, however, a potential is established which is no longer sufficient to control transistor 3 through. The operating point or the response threshold value of the transistor 3 is set by a Zener diode 2o located in its emitter lead, which is biased via a resistor 21 and is thereby kept conductive in the Zener area. If the voltage drop occurring across the resistor 15 is equal to or less than the Zener voltage, the transistors J), 6 remain blocked.

If the monitoring device is due to a false call the grounding of a line core (a and / or b) is used, the transistors 5 and 6 are controlled to be conductive, while the transistor 1 receives no control potential. An "O" signal is therefore established at the sampling point 7, while at the sampling point 8 a "1" signal occurs. The call then becomes a false call circuit provided for this purpose, in a manner not shown forwarded.

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3 claims,
1 sheet drawing, 1 figure

009839/1394

Claims (1)

A.Kegnier, R. Depreux 12-10
Claims; ) Circuit arrangement for monitoring a telecommunication line, in particular a telephone line, with which a second, initiated by the subscriber without the aid of the earth line, the exchange should be recognizable, characterized in that the supply resistor (9) connected to the earth potential terminal and the one with the working potential terminal connected feed resistor (15) or a part of the same a control voltage for an associated transistor amplifier (1.5 or 3.6) can be tapped that one (3 »6) of the two transistor amplifiers has a response threshold value which, in the case of one of the subscribers controlled loop current reduction by means of a resistor that can be switched into the line loop, and that the two transistor amplifiers deliver the same output potentials to a logic circuit (A) when they respond. Circuit arrangement according to Claim 1, characterized in that that transistor amplifier has the response threshold value which is controlled by the voltage drop at the supply resistor (15) connected to the working potential terminal. Circuit arrangement according to Claim 1, characterized in that the base of a first transistor (1) of the first conductivity type via a choke coil (11) and two resistors: (10, 22) to one (a) of two wires (a, b) of the communication line is connected that the common connection point of these two resistors via a third resistor (9) and the emitter of the first transistor are connected to the terminal leading to ground potential, that 009839/1394 ■. - T - -. - .- ·; -. ■ .. ■■ A.Regnier-R.Depreux 12-lo. the collector of the first transistor is connected to a first scanning terminal (7) of a scanning device (A) via the base-emitter path of a second transistor (5) of the second conductivity type connected with its collector to the ground potential terminal, that also the base of a third transistor (3) second conductivity type via a further choke coil (l4) and a fourth resistor to the other wire (b) of the communication line is connected, that the common connection point of the second choke coil and the fourth resistor (| via a fifth resistor (15) on the working potential. handling terminal is that the collector of the third transistor, a reverse biased zener 'diode (2o) is connected to the operating potential terminal and via a sixth resistor (21) to the Erdpotentialklemme over and that the collector of the third transistor seventh over a Resistor (24) to the base of the fourth transistor (6) he ster conductivity type; whose base is connected via an eighth resistor (25) and whose emitter is connected to the ground potential terminal and whose collector is connected to a second scanning connection (8) of the scanning device. - 009839/1394 Blank page