DE1085197B - Pilot level control device for two-wire transmission systems in communications engineering - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN Afommen, PATENT OFFICE

kl. 21 a 2 36/14

IPJTERNAT. KL. H 04IH

EDITORIAL EDITORIAL 1085197

S 57759 VIIIa / 21a ³

REGISTRATION DATE: APRIL 9, 1958

NOTICE
DECANNATION
AND ISSUE OF THE
DEVELOPMENT: JULY 14, 1960

The invention relates to a pilot level control device for automatic level control of two-wire transmission systems communications engineering.

Used for monitoring communication channels in terms of low frequency and carrier frequency Lines are used for pilot level control devices that monitor the transmission channels enable during operation. In this case, a pilot frequency used as a control variable is also used on the transmission side of the transmission system fed in. Selective pilot receivers acting on control organs are used to receive this pilot frequency provided, each of which is looped into the cable run at certain intervals at the output Line amplifiers are switched on. The regulating organs can, for example, be adjustable attenuators. The regulation itself takes place after Principle of the backward regulation, in which the controllable equalizing attenuator by means of the pilot amplifier is set so that the pilot level and thus the level of the transmitted message at this Position of the line always has the desired value. The automatic pilot control is of particular importance where channels branch off at certain points in the course of a carrier frequency connection or in the opposite direction. Here it is for the sake of maintaining the required signal-to-noise ratio as well as to avoid impermissible non-linear crosstalk or crosstalk necessary, the Adjustment of the level of the branch channels to the level of the channels passing through during operation to ensure.

The proportion of the costs of a pilot level control device in two-wire systems with a small number of channels is relatively high. In cases where such a regulation cannot be dispensed with, i.e. in systems with branch operation, a simplified regulation has therefore been adopted. In this case, the pilot frequency is only transmitted in one transmission direction of the system, but it is used as a control variable for both transmission directions. The control in both transmission directions by a pilot makes it possible to get by with one pilot receiver per amplifier field, which controls an attenuator arranged in the common transmission line. The regulation takes place for the signal voltages transmitted in the direction of the pilot frequency according to the already mentioned principle of backward regulation and for the signal voltages transmitted in the opposite direction according to the principle of forward regulation. This type of control is much more economical than a separate control for both directions of transmission, but it has the disadvantage that the attenuator IO

Pilot level control device

for two-wire transmission systems

communications engineering

Applicant:

Siemens & Halske Aktiengesellschaft,

Berlin and Munich, Munich 2, Wittelsbacherplatz 2

Dipl.-Ing. Ludwig Graf, Percha (Kr. Starnberg), has been named as the inventor

in the pilot-free transmission direction has to regulate the already amplified signal level and therefore

with regard to the required signal-to-noise ratio, it must meet considerable noise requirements.

The invention is based on the object of providing a way in which it is possible to overcome this difficulty in a simple way to eliminate.

For a pilot level control device for two-wire transmission systems communications engineering, especially for carrier frequency systems with a small number of channels with branch operation, preferably on overhead lines, with the line amplifier at the output

only one transmission direction of the system selective, changeable and possibly equalizing resp. Distorting attenuators for level control, pilot receivers acting in both transmission directions to receive one also only in this one

Direction transmitted pilot frequency are arranged and at which this pilot level control device once the transmission level in the direction of transmission of the pilot frequency according to the principle of backward regulation attenuation equalized and on the other hand the transmission level

the opposite direction to the same pilot channel controls or predistorted, the task is according to the invention solved in that a common transverse amplifier provided for both transmission directions an equally common to both directions of transmission

same adjustable, if necessary equalizing attenuator is connected upstream in such a way that the regulation of the attenuation fluctuations of the signal level takes place on the lower level side of the amplifier for both transmission directions.

009 550/230

The use of the known in the two-wire technique itself cross amplifier instead of a conventional two-wire amplifier enables the two transmission directions common attenuator with respect to - the 'Signalpeget both ■ Übertragurlgsrieh-ί directions on the lower level side of the amplifying means to be arranged so that more of this attenuator no particular Klirranforderungen must be asked.

On the basis of an exemplary embodiment, which is shown in the drawing, "the invention is intended in the following are explained in more detail. ''

The figure shows the block diagram of a cross amplifier for two-wire systems with a pilot level control device in the arrangement according to the invention. According to the method of the two-wire separation layer used here, the two mutually offset frequency bands in both transmission directions are via switch circuits of the high-pass filters HP 1 and HP 2 and the low-pass filters TP 1 and TP 2 is fed to the input of an amplifier V which amplifies the signal levels in both directions together.

The attenuator Ό, which is common to both transmission directions and to be set by the pilot amplifier PE, is connected upstream of the input of the amplifier V. -The ^; Channels branched off at this intermediate amplifier point are fed to further demodulation devices by means of fork G 1 via line Aab and the added channels are fed from suitable modulation devices on line Aan via fork G 2 into the continuous line P. ·

Claims (1)

Claim: Pilot level control device for two-wire transmission systems in communications engineering, especially! '' For carrier frequency systems with a small number of channels with branch operation, preferably on overhead lines, in which at the output of the line amplifier only one transmission direction of the system is selected, pilot receivers acting on variable and possibly equalizing or distorting attenuators for level control in both transmission directions to receive a pilot receiver also only in this direction transmitted pilot frequency are arranged and in which this pilot level control device on the one hand attenuates the transmission level in the transmission direction of the pilot frequency according to the principle of backward regulation and on the other hand controls or "controls the transmission level" in the opposite direction according to the same pilot channel. Vtfr equalized, characterized in that a 'common' transverse amplifier provided for both 'transmission directions' is preceded by an adjustable, 'optionally equalizing' attenuator, which is also common to both 'transmission directions', in such a way that the attenuation fluctuations '' of the signal transmission level are adjusted for both directions the lower level side of the amplifier. Considered publications:
Deutsche ^ ätentschriffiST] :. 874 '155. 1 sheet of drawings © 009 550/230 7.60