US1494382A - Means for preventing electrical interference - Google Patents

Description

fiMayZD, 1924. 1,494,382 v R. B. sHANcK MEANS FOR PREVENTING ELECTRICAL 4INTERFERENGE H Film may-27', 1921 CROSS-f/RE 3 NEUTRAL/ZIN@ f 1Q 5? hl/@ch 3513 Qu @Hoz-11mg v Patented Mey 2d, i924.

PATE? @Fidih ROY B. SHANCK, OF FLUSHING, NEW YORK, ASSIGNOR TO' AMERICAN TLEPI-IONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

MEANS FOR PREVENTING ELECTRICAL INTERFERENCE.

Application led May 27, 1921.

To r/.ZZ whom t 77mg/ 0071067171:

Be it known that l, ROY B. SHANGK, residing at Flushing, in the county ot Queens and State ot New York, have invented certain Improvements in Means for Preventing Electrical Interference, of which the following is a specification.

This invention relates to means for preventinof electrical interference between siO'e kspectively.

na-ling circuits and specially to an arrangement for preventing that form of interference between telegraph circuits which may be termed receiving-end cross-tire.

ln the operation of telegraph signaling circuits it is well known that when impulses are transmitted over one telegraph circuit an interfering current will be set up in other circuits paralleling the first circuit due to the mutual admittance between the circuit over which the impulses are being transmitted, a-nd the circuits paralleling the same. This interfering current will cause a disturbance in the terminal apparatus at both ends of the circuit in which the current is produced. The disturbance which is set up in the terminal apparatus oit said other circuit which is located in the same station in which is also located the terminal apparatus from which the impulses are being sent over the iirst mentioned circuit, may be termed sending-end cross-lire. The disturbance which is set up in the terminal apparatus oi' said other circuit which is located in the same station in which is also located the receiving apparatus of the said first mentioned circuit, may be termed receivingeend cross-tire. Sending-end crosstire has been successfully neutralized in circuits by connecting a condenser between the artificial lines of the duplex circuits.

It is the objectot this invention to provide a circuit arrangement for substantially neutralizing the receiving-end' cross-lire without increasing` the sending-end cross-fire such as has resulted :trom the use of arrangements heretotore designed for this purpose. v

Other and further objects of this invention will be apparent from the following description when read in connection with the attached drawing showing one Jform of embodiment of the invention.

Serial No. 473,118.

In the drawing, 1 and 2 represent two telegraph signaling circuits which have associated therewith the terminal circuits A and C respectively at station X and B and D respectively at station Y. The opposite. ends of the line 1 are connected with one of the windings of the bridge coils 3 and 4 respectively to the apeXes of which are connected the terminal circuits A and B re- Across the outer terminals ot the bridge coils 3 and 4 are connected the polar relays 5 and 6 respectively. The balancing networks ALl and ALL2 are connected with one winding of the bridge coils 3 and 4 respectively to balance the line 1 connected with the said other winding of the said coils.

The terminal circuit at A comprises a pole changer 7 and an auxiliary relay 8 which are controlled by current from the. battery 9 by the operation of the key 10. Batteries 11 and 12 are connected with the contacts of the armatures of the pole changer 7 and the auxiliary relay S. Since opposite poles of these batteries are grounded. current of opposite polarity will be applied to the two contacts of the pole changer and ot the auxiliary relay. The armature of the pole changer 7 is connected with the apex of the bridge coil 8 and the armature of the auxiliary relay 8 is connected through the condenser 13 and resistance '14 with the apex of the bridge coil 23, associated with the line 2.

The terminal circuit B, located at station Y at the opposite end of line 1, comprises a pole changer' 15 and an auxiliary relay 16, akkey 17 and a source of current 1S tor energizing the said pole changer and auxiliary relay. Batteries 1 9 and 20 arearranged to apply current of opposite polarities to the armature of the pole changer and also to the armature of the auxiliary relay. The armature of the pole changer is connected with the apex of the bridge coil 4, and the arma ture of the auxiliary relay 1G is connected through condenser 21 and resistance 22 to the apex of the bridge coil 24, connected with the line 2.

Bridged across the ends of the windings of the bridge coils 23 and 24 are the polar` relays 25 and 26 respectively. These coilsA also have associated with them the artificial lines AL3 and AL, which are adapted to balance the line 2. The terminal circuit C, which is similar to circuits A and B, comprises pole changer 27 and an auxiliary relay 29 controlled by current from the battery 3l by means of the key 32. Batteries 33 and 84 are adapted for connection with the armatures ot the pole changer and the auxiliary relay. Similarly circuit D comprises the pole changer 28 and the auxiliary relay 30, Which are controlled by current from the battery 85 by means ot the key 36. Batteries 37 and 88 are adapted for connection with the armatures of the pole changer and the auxiliary relay respectively. The armatures of pole changers 2T and 28 are connected with the apexes of bridge coils 23 and 24e respectively, and the armatures of the auxiliary relays #29 and 30 are connected through condensers and resistances with the apexes of the bridge coils 3 and a respectively.

It will be seen that all of the tern'iiual circuits are structurally identical and that the terminal circuits at the same end of each line are so arranged that the armature ot the auxiliary relay oteac-h terminal circuit is connected with the apex of the coil oit the other line circuit. The admittance between the two parallel lines l and 2 is represented by the condenser C1 shown in the drawing as bridged across the said lines at their mid points. It is to be understood, of' course, that such representation is purely symbolic since such capacity is normally uniformly distributed throughout the length ot the parallel conductors.

Having in mind the foregoing description Ot the signaling system in ywhich this inve-ntion is embodied, the invention can be more clearly understood 'from thefollowing description of the inode ot operation oi the system: Let it be assumed that telegraphie impulses are being transmitted from station X to station Y over line l andthat at the same time no impulses are being transmitted over line 2 in either direction between said station. It the signaling key l0 of circuit A, which is connected with line l, is closed, the pole changer 7 and the auxiliary relay 8 will be energized, thereby causing their respective armatures to move to their leithand contacts thus applying a` negative impulse through the armature of the pole changer to the apex ot the coil 8 associated with line l and a positive impulse from battery l2 through the armature ot' relay 8 to the apex of coil'23 associa-ted with line 2. The negative signaling impulse applied to line l will tend to cause interfering current to flow in line 2 in the directions represented by the vwavy arrows. The effect of this inter-tering impulse upon the receiving apbaratas 26 atrstation Y lwill be neutralized by the impulse olz opposite polarity represented by the dotted arrows which was impressed upon line 2 by the operation of the auxiliary relay 8 simultaneously with the impression oi the signaling impulse upon line l. This neutralizing impulse will be transmitted over line 2 towards the distant end, and, although it may be reduced in magnitude by such transmission, it will be capable of neutralizing the resultant interfering impulse which is also attenuated by transmission. ltis` of course, to be understood that the interfering impulse produced in line 2 by the signaling impulse impressed upon lineI l is not as great as the original signa-ling impulse and, conserpiently, the neutralizing impulse impressed upon line 2 by the operation ot the auxiliary relay associated with circuit need be only of sutcient magnitude to neutralize the interfering impulse. The directions of liow oi' the signaling, interfering and neutralizing currents vfor the circuit conditions just de* scribed are as shown by the various arrows upon the drawing.

lt the signaling lrey l0 is opened ilfor the 'transmission ot a signal ot opposite cl1aracter between station X and station Y, the armatures oit the pole changer 7 and the relay S will move to their right-hand contacts, thereby applying a positive impulse :trom battery l2 through the armature of the pole changerto the apex of the coil connected with the line l anda negative yimpulse from vbattery ll through the larmature of the auxiliary relay S to t-he apex ot the coil connected with line 2. The positive impulse which is produced in line 2 bythe impression of the positive impulse to line l will be lneutralized by the negative impulse oit corresponding magnitude applied to line 2 by the operation ot the auxiliary relay 8. The directions of tlow oil the signal-ing, interfering and neutralizing currents tor the circuit conditions just described will -be opposite to that represented by the arrows upon the drawing. ly careful adjustment the interfering impulses may be substain tially neutralized, and the receiving apparatus 26 associated with the end ot `line 2 at station Y, where sigi'ials are Vbeing `received over line l, will not be affected by the cross-lire between line l and line 2. It will also be seen than since the neutralizing impulses applied to the line under crossre are directed to the apex of the` coil connected with the said line` no detrimental eitect will be produced in Vthe receiving apparatus, such as 25, connected with thesaid line.

In like manner it will be seen that it signals are transmitted trom station Y to station X over line l and line is idle as hereto tore. the polar relay 25 connected with line 2 and located at stationX will not be aliected by interfering impulses produced in line 2 by the transmission of signaling impulses over line l.

Let it now be assumedthat signals are being transmitted simultaneously over lines l and 2 from station X to station Y. When key l() associated With the terminal circuit A is closed', the pole changer T and the auX- iliary relay 8 will be energized, and in consequence there will be impressed upon line l a negative impulse and upon line 2 a positive impulse which will serve to neutralize the interfering impulse produced in line 2 by the transmission of the signal over line l. 'When key 32 is closed, pole changer 27 and the auxiliaryfrelay 29 will be energized, and in consequence a negative signaling impulse will be impressed upon line 2 and the positive neutralizing impulse upon line l, Which will serve to neutralize the interfering impulse produced in line l by the impression of the signaling impulse upon line 2. Accordingly, the receiving apparatus 6 and Q6 connected With lines l and 2 respectively are rendered substantially free from the effect of cross-fire, although they Will respond in the usual Way to the transmission of the signaling impulse over their respective lines.

Although this invention has been shown as applied to two line circuits only, it is not thus limited, but is equally applicable to a system employing a greater number of line circuits. Furthermore, the invention is not limited to the particular form of circuit arrangement herein disclosed, since it might be embodied in other and different arrangements which will suggest themselves to those familiar With the art. The essence of this invention consists in the method and means for neutralizing receiving-end cross-lire by applying to the circuits exposed to crosstire a neutralizing impulse simultaneous with the application of a signaling impulse over another circuit, the polarity of the neutralizing impulse being opposite that of the signaling impulse and of such magnitude as to substantially equal the impulse produced in the exposed circuits by the signaling impulse transmitted over the said other circuit.

It Will be seen from the foregoing description that my invention discloses simple and effective means for protecting parallel telegraph circuits against receiving-end interference. Furthermore since the condensers C3 and C4, which are connected between the artificial line sides of each end of the circuits, are adapted to substantially neutralize sending-end interference, the effect of both the sending-end and the receiving-end interfering currents may be substantially reduced and the circuits rendered substantially free frominterference by means of the arrangement herein disclosed.

Although this invention has been described as embodied in a particular form and arrangement of parts, it is to be understood that it is capable of embodiment in other forms and arrangements Without departing from the spirit and scope of the appended claims. l

What is claimed is:

l. In a telegraph signaling system comprising a plurality of adjacent circuits, the method of reducing receiving-end cross-fire between said adjacent circuits when signaling impulses are impressed upon one of said adjacent circuits which consists in impressing uponthe other of said adjacent circuits impulses of a character adapted to neutralize the interfering impulses produced at the distant receiving station thereof by the transmission of signaling impulses over one of the said circuits.

9.. In a telegraph signaling system comprising a plurality of adjacent circuits, the method of reducing receiving-end cross-lire between said adjacent circuits, which consists'in impressing upon one of said adjacent circuits an impulse of opposite polarity to the signaling impulse impressed upon. the other ofsaid adjacent circuits. j

3. In a telegraph signaling system comprising a plurality of adjacent circuits, the method for reducing receiving-end.cross-fire between said-adjacent circuits which consists in impressing a signaling impulse upon one of said circuits, and in simultaneously impressing an impulse of opposite polarity upon each of the other of said adjacent circuits.

4. In a telegraph signaling system comprising a plurality of adjacent circuits, the method for reducing receiving-end cross-fire between said adjacent circuits which consists in impressinga signaling impulse upon one of said circuits, impressing an impulse of opposite polarity upon other of said circuits, and in reversing the polarity of the source of current connected with the latter of said circuits Whenever the polarity of the source connected with the former circuit is reversed'.

5. In a telegraph signaling system, the combination with two adjacent line circuits, of sending circuits and receiving circuits individual to each line circuit, each sending circuit being characterized by means for applying a signaling impulse to its respective line circuit, and also to apply simultaneouslyl an impulse of opposite polarity to the other of said adjacent circuits whereby receivingend cross-lire in the said other circuits may be reduced.

6. In a telegraph signaling system, the combination With two line circuits of polar duplex terminal circuits individual to each of said line circuits, each of said terminal circuits being adapted to apply a signaling impulse to the apex of the bridge coil of its respective line circuit, and also to apply loo simultaneously to the -apex of the coil of lthe ,otlierfline circuitan impulse having a polarity opposite to that vof the .signaling impulse.

7. In a telegraph signaling system, the combination with a line circuit oi a second line circuit, a .sending circuitand a receiving circuit individual/,to each ofk said line circuits, means yassociated with each of. said sending circuits to apply a signaling impulse to -its respective line circuit dand to control the simultaneousapplicationito the `other of said line circuits of, an impulse lof Opposite .polarity to the signaling impulse.

S. In a telegraph signaling system, the

combination -Witha plurality of line circuits, each hinting a bridge coil, a balancingvnetwork and a polar relay connected .at .each end, a terminal circuit individual to each line circuit comprising a kpole changer controlledby a key adapted to apply, signaling impulses of predetermined polarity to the said line circuit, and anauxiliary'relayalso controlled by the said key adapted to apply 'l tok each of said other line circuits impulses of polarities v.opposite to the signaling yimpulses applied to the line circuit with which a particular terminal circuit may be connected.

9. n ,zi telegraph signaling system, the

3f combination Witha line circuit of asecond line circuit, a terminal circuit individual to Lacasse teach line circuit comprisingsources of current of opposite` polarity `and vmeans for ,applying simultaneously impulses of opposite polarity to each of said line circuits.

10.111 a telegraph signalingsystem, the combination with a line circuit of a second line circuit, Ia-terminal circuit individualto each line circuit comprising sources of cui'- rent of opposite polarity, means for applying .a signaling impulse of predetermined .polarity tothe respective line circuits and current of'opposite polarity, andan auxiliary relay, the circuit being so arranged that theiarniature of the pole changer is connect- .ed with the line circuitfto which the said terminal circuit is. ,individual and the varmature `yof the auxiliaryrelay is connected with the other adjacent line circuits.

In `testimony whereof, I have signed my name tothisfspecication this 24th day of May, 1921.

:ROY B. SHANC'K.

Images