DD207137A3 - CIRCUIT ARRANGEMENT FOR AUTOMATIC TURNING OF CABLE DAMPING CHANGE - Google Patents

Abstract

The invention relates to a circuit arrangement for automatically balancing the cable detection change in the wireline communication technology. The aim and object of the invention is to provide an adjustable extension line, in particular for PCM regenerators, which realizes a monotonous rise in the dips with increasing frequency with only one actuator while maintaining the required Uebertragungsguete for a large control range. This is achieved by the fact that in the circuit arrangement for automatically adapting the Regenerativverstaerker to the damping of different Verstaerkerfeldlaenge with adjustable Verlaengerungsleitung, Entzerrverstaerker and peak detector erfindaess the controllable Verlaengerungsleitung from the series circuit of a four-terminal chain with LR Tiefpassglied and subsequent RC Tiefpassglied and a veraenderlichen conductance is formed ,

Description

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Title of the invention

Circuit arrangement for automatic adjustment of the cable loss change

Field of application of the invention

The invention relates to a circuit arrangement for automatically balancing the change in the cable loss, in particular for the automatic field length adjustment in PCM regenerators.

Characteristic of the known technical solutions

Modern regenerators have a large control range, eg. B, 35 dB, and are largely implemented in integrated circuit technology. It is customary to design the equalization in the regenerator for the maximum cable length and compensate for missing cable lengths and changes by an artificially adjustable Varlängerungsleitung.

By DD-WP 107 834 a circuit arrangement with a large control range has been known, but requires several actuators. However, the disadvantages of this technical solution are the high circuit complexity, the synchronization problems with multiple actuators, the unfriendliness of integration and the attenuation decrease above a certain frequency. A controllable extension line with a variable resistor based on the principle of the Bode equalizer is shown in DD-WP 83597. This arrangement also requires a high circuit complexity, also has no monotone Dämpfungsanstiag with dsr frequency and requires a range of variation of the variable resistance of several Zshnerpotenzen,

392 * 053808

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Furthermore, by Tarbox, R, A. in Proceedings of the IEs, March 1969, pp. 363-364, An automatic equalizer for digital repeatered lines, a simple variable line simulation, consisting of an ohmic resistance in the longitudinal branch and a series circuit bridged with a resistor capacitance and a variable resistor in the shunt branch , has been described. The disadvantage of this arrangement is the insufficient reproduction of the attenuation curve of the cable and the associated insufficient signal regeneration.

Ю Furthermore, a circuit arrangement for a variable extension line has become known, which is designed as a voltage divider, in the longitudinal branch has a parallel circuit of an inductor and a resistor and in the transverse branch consists of a series circuit of a resistor bridged with a capacitor and a diode actuator. A disadvantage of this arrangement is that, in particular for small resistance values of the diode actuator, a complex pole pair is formed in the transmission line, which degrades the transmission properties of the regenerator for the PCM. On the other hand, the ohmic damping of the reactances only achieves a small range of control.

Object of the invention

The aim of the invention is to provide a circuit arrangement for a variable extension line for regenerators, welehe despite low component cost and compliance with the required transmission quality allows a large control range.

Explanation of the essence of the invention

The invention has for its object to provide a variable extension line for regenerators, which realizes a monotone increase in attenuation with increasing frequency with only one actuator in a large control range and thus takes into account the requirements of modern regenerator circuits

 According to the invention this problem is solved in that in the circuit arrangement for controlling the frequency-dependent attenuation, in particular for automatic Ausregel the change of

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Cable attenuation and for self-supplementing the lack of attenuation at different cable lengths of field lengths in message transmission equipment the variable extension line between the cable and the equalizer amplifier with subsequent peak detector by the series connection of a four-pole, consisting of LR Tiefpaßglied and downstream RC Tiefpaßglied, and a variable conductance is formed ,

Ausfuhrunqsbeispiel

The invention will be explained below with reference to an exemplary embodiment. The related drawings referred to are as follows:

Fig. 1 erfindungsgeraäße arrangement of the variable extension line in the regenerator

Fig. 2 transmission characteristic of the extension line according to the invention

Thereafter, as shown in FIG. 1 to the cable 1, the adjustable extension line 2 is connected, which is part of the regenerator and self-supplementing the lack of attenuation at different cable lengths is transmission line and automatic compensation of the change in the cable attenuation a _K serves. The controllable extension line 2 according to the invention consists of the input side in the longitudinal zwaig ohmic resistance Rl, which is connected in series with the inductance L. The inductance L is connected to the ohmic derivative G, whereby the LR Tiefpaßglied is formed. In this case, the resistor Rl will usually be the replacement internal resistance usually inserted between cable 1 and nailable extension line 2 attenuator. At the connection point of the inductance L and the ohmic derivative G, second residual resistance R2 is connected, which with the downstream capacitive derivative C forms the RC low-pass element. Dia quadrupole chain from the LR Tiefpaßglied and the RC Tiefpaßglied is complemented by interconnecting the ohmic derivative G and the capacitive derivative C with the variable Leitwort g to a series circuit.

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The variable conductance g on the other hand is at reference potential and is controlled in a known manner by the equalizer amplifier 3 downstream peak detector 4. The equalizer amplifier 3 is coupled on the input side to the connection point of the second ohmic series resistor R2 and the downstream capacitive derivative C.

The effect of the variable extension line 2 is based on two real poles and a real zero. For large values of the variable conductance g, the zero position in the PN plan of the network shifts with the coordinates and jw after high values. The two real poles cause a strong damping of the high frequencies.

In the case that the variable conductance g becomes small, one pole is compensated by the zero, while the other pole is shifted to high values, whereby the attenuation a, ½ transmission area is small.

The attenuation a .. at low frequencies is determined by the relation of the input side in the longitudinal branch lying ohmic resistance Rl for ohmic derivative G of the LR Tiefpaßgliedes and the variable conductance g.

By Fig. 2, the achieved accuracy of the controllable extension line 2 according to the invention is shown in comparison with a medium transmission cable. 3is to the frequency normalized to the bit period T frequency 2 Tf = 1, the course of the missing cable length is well approximated by the adjustable artificial extension line 2, above the center of gravity increases the attenuation a., Still monotone. The required range of variation of the variable conductance g as a parameter is for one rule

of 35 dB 3 · 10 ² .

Claims (3)

Ч ^l "> * * ν H '' Г \ J -J ^ w ^: j Q о claim of claim 1, automatic loss control circuit, comprising a variable extension lead, the equalizing amplifier and the peak detector, characterized in that the variable extension lead (2) consists of a series connection of a quadrupole chain consisting of an LR low-pass filter and a downstream RC low-pass filter , and a variable conductance (g) is interconnected. 2. A circuit arrangement for automatic Ausregein the cable loss change according to item 1, characterized in that the LR-Tiefpaßglied in the longitudinal branch of a series circuit of an ohmic resistance (Rl) and an inductance (L) and in Cuerzweig has an ohms before derivative (G). 3. Circuit arrangement for automatic adjustment of the cable loss change according to item i and 2, characterized in that the eingangsseitiga ohms marriage. Resistance (Rl) of the L ^ -Tiofpaßgliedes Ersatzinnenvviderstand the usually between cable (1) and adjustable extension line eingafügt attenuator. 1 Saita