DK142298B - Coupling for transmitting telegraph and data signals at any high speed over a direct current transmission system consisting of symmetrical and galvanically wired wiring. - Google Patents

Description

\ £ a / OD FOREIGN66ELSESSKR1FT 142298 DENMARK <»'> in ,, α." Η 04h 25/00 § (21) Application No. 1506/69 (22) Filed on 19 · Mar. 19 ^ 9 (24) Race day I9. marten. 1969 (44) The application presented and the publication document published on 6 Oct · 1980

DIRECTORATE OF

PATENT AND TRADEMARKET SYSTEM (30) Priority baked from death

Mar 20 1968, 4158/68, CH

(71) SIEMENS SHARE COMPANY, Berlin and Munich, Wittelsbacherplatz 2, 8 Muenchen 2, BE.

(72) Inventor: Hans Blauert, Kaerntner-Platz 5, 8 Muenchen 21, BE: Ernst Schuhbauer, Prochintalstrasse 6, 8 Muenchen 54, BE.

(74) Plenipotentiary in the proceedings:

International Patent Office. ___ (54) Coupling for transmitting telegraph and data signals at any high speed over one of symmetrical and galvanically wired wiring consisting of direct current transmission systems.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a switch for transmitting randomly high-speed telegraphic and data signals over a symmetrical and galvanically wired direct current transmission system, in which the internal resistors of the transmitter and receiver both exhibit a low ohmic, mismatch to the line, at which transmitter and receiver two-wire duplex operation is included in each transverse branch of a bridge coupling, one of the bridge branches parallel to the transmitter containing the transmission line and a first bridge complement resistance and the second parallel bridge branch containing an artificial wire and a second bridge complement resistance.

In the field of remote writing, it is known to transmit the individual telegraph elements in the characters in the form of direct current pulses. If a cable is used as a cable, the interference between capacitive and inductive couplings that occur between the individual conductor pairs in the cable will occur. Within the voice frequency band, the interference rate increases approximately proportional to the transmission rate. As with regard to the cross-talk disturbance, certain requirements must be met, the transmission rate of such wires cannot be arbitrarily chosen at high rates.

For reducing the cross-talk disturbance, it is known to select the telegraph transmit voltage so low that the cross-talk disturbances are kept below a set value.

However, since at the same time as the reduction of the telegraph transmission voltage increases, the distortion is necessary, special measures must be taken to reach a satisfactory solution in this way. For this purpose, a coupling is known which permits a significant increase in the telegraphing speed of such a DC transmission system and, in spite of this, makes it possible to avoid the above-mentioned disadvantages in the form of cross-talk disturbances and distortions. This is achieved by reducing the time constants of the wires. To this end, the internal resistances of the transmitters and receivers present in the transmitting and receiving devices are reduced, and the input and output resistance of the line is reduced in approximately the same proportion as the telegraphing speed must increase from a basic telegraphing speed.

With such a low ohmic mismatch on both sides of the wire, it manages to keep the wire's time constants so small that the charging and discharging of the conductive capacities associated with direct current transmission occurs so quickly that even the shortest, very high speed telegraph elements reach the inverted state. on the receiving side. This reduces the distortions, or with the same distortion permits transmission over longer wires.

In addition to a four-wire duplex or two-wire simplex operation, a DC transmission system working according to this principle also enables two-wire duplex operation. Two-wire duplex operation is known in the field of DC telegraphy. In this mode of operation, the transmission line, one artificial wire adapted to its length and two resistors form a bridge coupling. The transmitter and receiver are placed in the bridge diagonals. This ensures that a given end station's own receiver remains unaffected by transmission from the station. However, each transmitter and receiver terminal station requires an artificial wire that is individually tuned to the available cable length. In this connection, the artificial wire must be alternately equalized in two interconnecting stations. As such equalization of artificial wires is very difficult and is associated with a large supply of accurately adjustable components, this type of two-wire duplex operation has not gained widespread by DC telegraphy.

The invention aims at removing the disadvantages of two-wire duplex operation in known plants.

According to the invention this is achieved by the fact that the transmitter's internal resistance, independent of the receiver's input resistance, is extremely low ohmic with respect to the bromine resistors.

The solution proposed by the invention allows an independent equalization of the artificial conduit in each of the two terminals in a simple manner. The supply of components needed to equalize the artificial conduit is significantly reduced. The input station's input resistance is determined by the transmitter's internal resistance, so that the substantially higher parallel-coupled impedances in the artificial wire are virtually ineffective.

According to a further development of the invention, it is proposed that, in four-wire operation, the transmitter's internal resistance, independently of the receiver's maladjustment, exhibit an extremely low ohmic maladjustment to the wire. This avoids another problem that occurs in a low-voltage DC transmission system. This problem consists in the fact that high transmit voltage information links and low transmit voltage information connections in neighboring conductors affect the same circuit, which can cause cross-speech distortions which cause distortions or complete forgeries.

The invention is explained with reference to the figure. This shows a transmit part TnS and a receiver part TnE in a subscriber station. A leading line L, with its two wires a and b, enables two-wire duplex operation with another, similarly constructed but not shown subscriber station. A transmission line mimicking artificial wire is designated N. An electronic telegraph signal transducer attached to the transmit portion is designated by ETSI and an electronic telegraph signal transducer with ETS2 attached to the receiver portion. In addition, an amplifier designated by LV is attached to the receiver part. By means of two bridge resistors R1 and R2, the transmission line and the artificial wire, the bridge connection known for DC wiring is formed from two-wire duplex operation. In this coupling, the transmitter is in one and the receiver in the other bridge diagonal. In accordance with the invention, the transmitter's internal resistance, independent of the receiver's input resistance, is selected to be extremely low ohmic with respect to the bromine resistors L, N, RI and R2 such that the resistance of the end station is thereby determined. In this case, the transmitter's internal resistance, which is the resistance of the electronic telegraph signal transmitter ETSI, is significantly less than the receiver's internal resistance, which in this case is the input resistance of the amplifier LV.

This resistance due to the already mentioned low ohmic fault adaptation to the wire itself is less than the wire's wave resistance. The artificial wire N is constructed in a manner known per se by resistors and capacitors. The relatively high impedances in the artificial wire are parallel to the low internal resistance of the transmitter. The relatively large internal resistance of the transmitter relative to the transmitter in the receiver is partly connected in series with the impedances in the artificial wire. This means that the input station input resistance is determined by the low internal resistance of the transmitter. On the other hand, the significantly higher, pair-connected impedances in the artificial wire can be disregarded. In this way, it is possible to make the equalization of the artificial wires in each of the terminals independent of each other.