US1758900A - Superimposed telegraph circuits - Google Patents

Description

May 13, 1930. R. v. MORGENSTERN SUPERIMPOSED TELEGRAPH CIRCUITS Filed March 5, 1928 hum iobzxz A FSQE zmPGm .535 uozw bum EZEuu Zmneutor fionald YMo qehs fem Patented May 13, 1930 UNITED STATES.

PATENT OFFICE RONALD V. MORGENSTERN, OF METUCHEN, NEW JEESEY, ASSIGNOR TO THE WESTERN UNION TELEGRAPH COMPANY, OF NEW YORK, N. Y., A CORRORATION OF NEW YORK Application filed March 8,

This invention relates to superimposed circuits, particularly to-the method of coupling the superimposed circuit to the circuit or on cuits on which it is superimposed.

The object of the invention is to provide a novel method of conductively coupling the superimposed circuit to the electrical center of the source of potential employed to send signalingcurrent over the circuit on which up the superimposing is done. This condition 1s necessary in'superimposed circuits in order that the circuit on which the superimposing is done shall not interfere with the superim osed circuits.

t is also desired by this invention to pro vide the best possible superimposed circuits with the least possible effect on the circuits upon which they are superimposed.

The invention may be explained by reference to the accompanying drawing which shows the embodiment of the principles of the invention in a superimposed telegraph system. In the system illustrated, two metallic telegraph circuits have superimposed on them a third metallic telegraph circuit upon I which in turn is superimposed a ground return telegraph circuit. In the telegraph system illustrated by the drawing, all the circuits shown are arranged for the simultaneous. transmission of signals in opposite directions, but it is understood that the invention is not to beconsidered as limited to such a system. On the figure the line conductors 11, 11 are used in a side circuit which is balanced for duplex operation by an artificial line 12, the

relay coils 13, 14, 15, 16 beingsuitably connected in such a way that the transmitter 17 at the same station does not produce actua tion of the relay. A similar arrangement is provided at the other terminal set of this side circuit, and at the terminal sets of the side gizr cuit which'includes line conductors 12, The relays at the terminal sets are preferably so arranged that the coils which are con- SUPFEBIIMPOSED TELEGRAPH CIRCUITS 1928. Serial No. 258,948

nected in the main line, e. g. coils 13 and 15, have twice the number of turns of the coils in the artificial line, e. g. coils 14 and 16. The advantage of this arrangement is found in the fact that with a iven winding space on a relay it is possible %y this arrangement to secure a greater number of ampere turns to operate the relay than can be secured by making the artificial and main line coils contain the same number of turns. This is explained in detail in' U. S. Patent No. 1,584,682 to Albert Atherton' and George W. Janson.

The transmitter 17 is schematically represented by a tongue 18 having alternate contacts which are connected to generators 19 and 20 for supplying current impulses of o posite polarities to the line through the win ingsv of the receiving relay.

hen transmitting signals over the side circuit which includes conductors 11, 11, current impulses of opposite polarities are sent to line rom potential sources 19 and 20 by way of tongue 18 and one or other of its contacts. There is a tendency for current to flow through shunt 21 by reason of its connection across the two oints at which battery is ap lied to the terminal set on the side circuit, ut this tendency is minimized because of the nature of the shunt. The inductance 22 and resistance 23 of the shunt are so regulated in relation to the constants in the circuit that the shunting action of the shunt circuit at the beginning of a signal is practically suppressed. It is not thereafter ermitted to obtain a substantial value be orethe next current reversal.

The- conductors 24, 24 connect the midpoint a of inductive resistance coils 22, 22 to the terminal set on the phantom circuit which is like that provided at the terminals of each of the side circuits. Artificial line 32 balances for duplex operation the phantom circuit. The

transmitter 37, schematically represented as comprising a tongue 38 did a pair of contacts connected to potential sources 39 and 40, is

connected to the junction point of coils 33, 34, 35, 36 of the receiving relay at the terminal set on the phantom circuit. A similar terminal set is provided at the other end of the phantom circuit. The main line coils of these relays may, like those at the terminal sets of the side circuits, com rise twice as many turns as the correspon ing coils in the artificial line. In order to rovide a ground rev The inductive resistance coil 26 is not inducreverses the polarity of the signalin tive to currents originating at the terminals of the ground return circuit, but is highly inductive to currents from the phantom circuit.

A conductor 28 leads from the electrical midpoint a of coil 26 to a terminal set 29 for the ground return circuit. The terminal set includes an artificial'line 30, relay- coils 31, 31 and a. transmitter connected between ground and the junction of the relay coils and schematically represented as before, by a tongue and two cooperating contacts connected to potential sources of opposite polarity. The operation of the system will be apparent from the following:

When transmission takes place over the side circuit comprising conductors 11, 11, current impulses of opposite polarities are transmit ted to line from sources 19 and 20 by way of tongue 18 and one or the other of its contacts. The shunt 21, by reason of its connection across the terminals of the transmitter 17 tends to absorb part of the line current, but this tendency is minimized because of the nature ofthe shunt. The high inductance and the low resistance of the shunt are so regulated in relation to the constants of the circuit that the shunting action of the shunt circuit at the beginning of a signal is practically suppressed and is not thereafter permitted to attain a substantial value before the next current reversal.

When the transmitter 17 at the terminal set the impedance oft e shunt is very igh and allows a very small current to flow through it to the battery return. This means that at the beginning of the signal there is a very small increase in the voltage drop across the resistance placed in the connection from potential sources 19, 20 to contacts of transmitter 17,

due to the shunt on the battery su ply. .For

' this reason practically the same voltage is applied to the line conductor at the beginning current,

of a signal as would be the case if this shunt was not present.

As the length of timeduring Which the same polarity of signaling current is im pressed in the circuit increases the amount of current through the shunt increases, and the voltage across the resistance in the leads from the potential sources to the transmitter contacts also increases,'lowering the potential applied to the line circuit. If the inductance of the shunt is high enough in relation to its resistance, i. e., if the time constant of the shunts is sufficiently great, the distant receiving relay is reversed in response to the reversal of signaling current before there is any appreciable decrease in signaling current strength, and the shorter the time length of signal the less final effect the shunt will have in reducing the strength of the signaling current. This is important because it is always the short signals which are the most diflicult totransmit over a circuit.

The same explanation applies to the action of shunt 25 in preventing any appreciable effect of the hantom circuit transmitter upon the superlmposed circuit with ground return.

The resistance of the shunt can be made as small as is compatible with the minimum voltage which must be applied to the line. The lower the shunt resistance the greater its time constant.

Since, the shunt is non-inductive to the superimposed currents, the impedance which it offers to these currents is due only to its resistance, which should be made as low as is practicable. It will be. further observed that the effective resistance which it ofiers to the superimposed current is equal to one-fourth the resistance oflered by the shunt to the circuits on which the superimposing is done.

It is a parent that upon a judicious selection of t e values of inductance and resistance of the shunt circuit depends the eflicien cy with which the desired results are attained. If the inductance of the shunt is of appropriate value compared to the rateof current reversal, the shunt circuit instead of absorbing, may even aid, by reason of the stored magnetic energy, in establishing the current reversal in the line.

The use of a single inductive resistance coil tapped at its center, rather than of two separate coils, offers the advantage of minimum inductive reactance to the currents from the superimposed circuit as well as of maximum inductive reactance to current from the circuit upon which the superimposing is done.

In the example illustrated, the adjustable resistances 23 and 27 may have a value of 400 ohms; coils 13 and 15 may have 3500 turns and coils 14 and 16, only 17 50' turns. Obviously, however, these values are given merely by way of example and may be varied widely to meet varying circuit conditions.

conductor of a circuit having a round re-' turn connected to the midpoint 6 said coil,

- whereby the inductance 0011 offers great.im-

connected to said conductor, w

tial connected to a pair pedance to the flow of current from the said metallic circuit and negligible impedance to flow from said ground return circuit.

2. The system according to claim 1, in which the resistance and inductance of the shunt circuit are adjusted in accordance with the voltage of said source, the characteristics of the metallic circuit, and the speed of signal transmission from said source to provide minimum'shunt eifect of the shunt circuit upon said source.

3. The method of operating a system according to claim 1 which comprises regulating the relation of the speed of signal transmission to the constants of the shunt circuit and of the metallic circuit so that substantially the same volta e is applied to the metallic circuit at the beginning of a signal as would be the case ifthe shunt were not present.

4:. A superimposed telegraph system, comprising a metallic circuit, 'a source of potenof terminals thereof, a shunt circuit connected to said terminals and including an inductance and adjustable resistance, a conductor of a third circuit connected to the electrical center of said shunt circuit, and a source of signalin potential hereby the shunt circuit oifers great impedance to the flow of current from said metallic circuit and negligible impedance to flow from said third circuit conductor.

5. The system according to claim 1, in which the resistance and inductance of the shunt circuit are adjusted in accordance with the voltage of said source, the characteristics of the metallic circuit and the speed of signal transmission of the metallic circuit and the speed of signal transmission from said source to provideminimumshunt efifect of the shunt circuit upon said source, the resistance of the shunt circuit being made assmall as is compatible with the minimum voltage which must be applied to the line.

6. In a superimposed telegraph system, a pair of metallic side circuits, a source of plex operation,

potential for each side circuit connected to a pair of terminals thereof, an inductive resistive shunt for each side circuit connected to a pair of terminals, a conductor of a phantom circuit connected across the electrical centers of said shunt circuits, a source of potential for the phantom circuit connected to said conductor, an inductive resistive shunt connected across the terminals of said last I mentioned source, and a conductor for a transmlttmg cn'cuit connected to the electrical center of said last mentioned shunt.

7. In a superimposed telegraph system, a metallic side circuit, an artificial balancing line therefor, a pair of transmitting terminals for the side circuit, a receiving relay comprisin coils connected between each terminal and t e line conductor and between each terminal and the artificial line,- anda source of signaling currents connected to said pair 'of terminals whereb signal currents from said source are ine ective to operate said relay, a shunt circuit connected across said pair of terminals comprising a highly inductive resistance coil, and a conductor of a phantom circuit connected to an intermediate point of said coil, whereby signal currents from said source have negligible effect upon said phantom circuit.

8. In a*superimposed telegraph system, metallic side circuit sets arranged for dusources of signaling poten tials connected to conjugate transmittin terminals of said sets, a terminal set arrange for duplex operation, and means connecting said sets to provide a phantom circuit for said terminal set comprising shunt circuits connected .across the terminals of the signaling sources of said side circuit sets and including inductance coils so wound as to be noninductive to currents from said phantom set and highly inductive to currents from said side circuit sets, whereby interference is prevented between the transmiitter of each set and'the receiver of its own or any other set.

9 In a telegraph system, a transmission line, a terminal set adapted for connection to said transmission line, an artificial line for balancing said line with respect to transmitted current from said terminal set, a highly inductive shunt circuit connected across the conjugate transmitting terminals of said set, duplicate apparatus at the other end of the transmission line, and means connected to the electrical centers of said shunt circuits for completing a'superimposed circuit over said transmission line.

10. In a superimposed telegraph system, a pair of side circuits each comprising a source of si al' potentials connected to a pair of termlnals t ereof, a phantom circuit including a source of signaling potentials directly connected-to said side circuits and means in said phantom circuit connection for preventing interference in said phantom circuit from said side circuit signaling sources, said means comprising an inductance coil in shunt to the terminals of each source, a grounded circuit superimposed upon said phantom circuit and a means in-the connection ofsaid grounded circuit for preventing interference from the phantom circuit in said grounded circuit, said last mentioned means comprising an inductance coil in shunt to the phantom circuit signaling sources.

In testimon whereof-I affix my signature.

RONXLD V. MORGENSTERN.

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