DE1057175B - Hybrid circuit with capacitors to achieve a high-pass effect - Google Patents

Description

GERMAN

In telecommunications technology, hybrid circuits are used to connect four-wire lines to two-wire lines. In many cases, capacitors are inserted into the forks to suppress line noise and low signal frequencies, so that the effect of a high-pass filter arises. Such a circuit is shown in FIG. The capacitors Cl to C 4 are in this intended for speech transmission hybrid circuit capacitance values of each of 1 μ ¥.

The cable replica circuit connected to terminals 3, 4 should simulate the impedance of the cable in the transmission range (300 'to 2400 Hz) as precisely as possible in order to ensure perfect decoupling of the four-wire lines. Such afterimage circuits generally contain a relatively high capacitance in the series branch. In FIG. 2, for example, a replica circuit suitable for operation with pupinized lines is shown. This configuration is known as the "Hoyt replica".

The capacitor C5 located in the series branch of this circuit arrangement has capacitance values between 3 and 15 μΈ, depending on the type of Pupin line used. When using a long-distance transmitter at the input of the hybrid circuit, the initial value is 6 μΡ. For a universal usability of the fork, the individual elements of the replica must be changeable. In this case, particular difficulties arise in the implementation of the capacitor C 5, since it has to be assembled from individual capacitors of large dimensions and therefore cannot be accommodated in the housing provided. Similar difficulties also arise with other simulations that are not dimensioned for pupinized lines, since the series capacitor generally has large capacitance values.

To avoid this difficulty, it has already been proposed to induct the capacitor in couple the circuit and select the transmission ratio accordingly designed for this purpose transformer as small as possible. With this solution, however, additional Space required to accommodate the transformer. In addition, it brings a not inconsiderable one Increase in effort.

An additional difficulty arises from the fact that the long-distance line transformer connected to the fork input causes a reduction in the capacitive component of the impedance connected to terminals 1, 2 . This component can be compensated for in the simulation by enlarging the series capacitor C 5. However, if the input resistance is inductive, then the

Hybrid circuit with capacitors
to achieve a ho clip ate effect

Applicant:

Standard electrical system Lorenz

Stock corporation,
Stuttgart-Zuffenhausen,
Helimuth-Hirth-Str. 42

Dipl.-Ing. Günther Rahmig, Stuttgart, Dipl.-Phys. Horst Fricke, Stuttgart-Zuffenhausen, and Werner Wessinger ₁ Ditzingen (Württ), have been named as inventors

Simulation instead of the capacitor C 5, an inductance can be switched on. This brings an additional increase in expenditure, since the inductance would have to be controllable to compensate for different input resistances.

With the aid of the invention, it is possible to completely avoid reactance in the series branch of the simulation.

In a hybrid circuit with capacitors to achieve a high-pass effect for connecting a According to the invention, the fork equilibrium is preferably a pupinized two-wire line to a four-wire line due to one that does not fully reproduce the line resistance at two output terminals connected network and by appropriate dimensioning of the arranged within the hybrid circuit Capacitors manufactured in such a way that one is necessary in the replica, with the elimination of one Reactance to compensate for a capacitive component of the line resistance on the line side Capacitor or to compensate for an inductive component of the line resistance on the simulation side Capacitor a much smaller, preferably controllable capacitor connected in parallel is.

Due to the connection according to the invention, relatively small capacitors in parallel with one of the the capacitors causing the high-pass filter are in each case for the frequency range to be transmitted the fork balance established, although the

909 510/332

Claims (2)

Replication is incomplete due to the omission of the series capacitor or the series inductance. According to a further embodiment of the invention, the additional capacitor is switchable and optionally to be arranged in parallel with the capacitor C 2 or C1 located in the replica branch or in the two-wire branch of the fork 5. 3 shows an exemplary embodiment of the hybrid circuit according to the invention. The adjustable additional capacitor is denoted by C 8. At the entrance of the fork there is a transmission transmitter FLÜ. Depending on the type of line, the capacitor C 8 is now connected in parallel to either the capacitor C1 or the capacitor C 2. The capacitor C 8 has a maximum capacitance of 0.15 μ ¥. This achieves a control range of ± 15%. This range corresponds to a controllability of the actually necessary capacitor C 5 from 6 μΡ to infinity and a corresponding inductance. The high-pass properties of the fork are not affected by the addition of the capacitor. In the most favorable case, the increase in attenuation is only a few percent, measured at the cut-off frequency. In the blocked area, the attenuation reduction is also only a few percent. Claims-. 1. Hybrid circuit with capacitors to achieve a high-pass effect for connecting a preferably pupinized two-wire line to a four-wire line, characterized in that the fork equilibrium is achieved by a network connected to two output terminals that does not fully simulate the line resistance and by appropriate dimensioning of the capacitors arranged within the hybrid circuit in the It is produced in such a way that, with the omission of a reactance (C5) necessary in the simulation to compensate for a capacitive component of the line resistance to the line-side capacitor (Cl) or to compensate for an inductive component of the line resistance to the simulation-side capacitor (C2), a significantly smaller, preferably adjustable capacitor (C8) is connected in parallel. 2. Hybrid circuit according to claim 1, characterized in that the additional capacitor (C 8) switchable either in the next image branch or in the two wire branch of the "fork capacitor (Cl or C2) is added in parallel. 1 sheet of drawings © 909 510/332 5.59