US965368A - Submarine-cable telegraphy. - Google Patents

Description

3. G. BROWN. SUBMARINE CABLE TELEGRAPHY. APPLICATION FILED BEPT. 10, 1907.

Patented July 26,1910.

2 SHEETS-SHEET 1.

TERS co., WASHINGTON, n. c.

rug name S. G, BROWN. SUBMARINE GABLE TBLEGRAPHY.

APPLICATION FILED SEPT. 10, 1907.

Patented July 26, 1910.

2 SHEETS-SHEET 2.

I\Ill ca, WASNLNGFDN, u. c.

SIDNEY GEORGE BROWN, OF LONDON, ENGLAND.

' SUBMARINE-CABLE TELEGRAPI-IY.

ceases.

Specification of Letters Patent.

Patented July 26, 1910.

Application filed September 10, 1907. Serial No. 392,108.

To all whom it may concern:

Be it known that I, SIDNEY GEORGE BROWN, a subject of the King of Great Britain, residing at 4 Great Winchester street, in the city and county of London, England, electrical engineer, have invented certain new and useful Improvements in or Relating to Submarine-Cable Telegraphy, of which the following is a specification.

This invention relates to submarine cable telegraphy, and has for its object to increase the speed in connection with the transmitting and receiving of signals, and generally to improve the working of such systems.

By my invention I am enabled to utilize for signaling purposes, not only the quick changing or signaling currents as they are called, but also the slow discharge currents which are due to the charging up action of the cable when a succession of signals of the same sign are transmitted.

Hitherto it has been found necessary to prevent the discharge currents from passing into the receiving instrument, and the present invention consists of means whereby it is possible to utilize such currents, in such a manner that a signaling speed from 50 per cent. greater than the present rate may be obtained.

l/Vhen signals are sent into a line, two types of current impulses namely the signaling or quick changing currents and the slower discharge currents from the cable, arrive, at the receiving end of the line. If for example a cable be directly connected to a recorder without the intervention of a blocking condenser, or other equivalent arrangement for preventing the discharge cur rents from flowing through the instrument, a succession of signals of the same sign arriving at the recorder, will produce a current through the coils of the recorder, which increases rapidly at first, and then less rapidly, and finally tends to a constant value producing a curve on the tape somewhat like the curve A, in Figure l of the accompanying drawings. The eflect of interposing a blocking condenser at the receiving end, will be to eliminate the slowly rising discharge current, and only permit the variations of the saidcurrent to arrive. The re sult will be a curve such as B, Fig. 1, in which the ordinate is roughly proportional to the rate of change of the ordinate of curve A. Such a curve is called a quick changing or signaling current. The curve A is called a slow, or discharge current.

Up to the present time it has been considered necessary to prevent the discharge current from flowing through the receiving siphon recorder or relay, by means of a condenser in series with the receiver, or in other equivalent way. Now an inspection of the curves in Fig. 1 will show (what is of course well known) that the action of the condenser while it sharpens the signals, at the same time largely reduces the amplitude of the arrival currents, and consequently the power available to operate the receiving instrument. I have discovered that by the application of the means hereinafter described, it is possible to utilize a considerable proportion of the socalled discharge current,

as well as the signaling current to operate the recorder or relay. I therefore permit the proper proportion of the discharge current to pass through the receiving instrument by increasing the capacity of the series blocking condenser, by shunting such condenser with a resistance, by increasing the induction of a magnetic shunt across the in strument, by increasing the resistance in series with such shunt, or in any other suitable way.

For the purpose of my invention there may be an automatic transmitter, operated by a sending battery of the kind usually employed. The receiving instrument is a relay, preferably of the type described in my British Letters, Patent No. 1434 of 1899, the tongue being preferably of the character described in my British Letters Patent No. 12,500 dated 29th May 1906. The relay tongue is adapted not only to operate a direct writer for recording the signals and the sending-on relays, as heretofore, but also controls the current in a local branch circuit, hereinafter called the reaction circuit, in which is included a subsidiary coil on the relay, so arranged that when the tongue makes contact with one of the surfacesof the drum of the relay, a current is caused to flow through the circuit and the subsidiary coil on the relay, in such a directionthat it tends to move the tongue to the side of the drum opposite to the contact which supplied the current in the said circuit, thereby producing a counteracting force which determines the delineation of the signals.

In order that my invention may be clearly understood and carried into effect, I will proceed to describe the same with reference to the further diagrams represented in the annexed drawings, Fig. 1 being a diagram showing the curves produced on the tape by the slowly rising discharge current and the quick changing or signaling current; and Fig. 2 being a diagrammatic view of an arrangement of apparatus adapted to accomplish the objects of my invention, and Fig. 3 a diagram illustrating the shape of the current wave resulting from my improved mode of working, compared with the shape of the current wave which would be obtained without the counteracting force, and also illustrating the manner in which the signals are emphasized and perfected.

According to the arrangement illustrated in Fig. 2, the apparatus may comprise a line wire A, with a receiving condenser n, which is shunted with a suitable resistance n The line wire is in operative connection with the coil 0; of the relay, so as to operate the tongue a arranged to move across the surface of the revolving drum which is provided with contact surfaces a and an insulated portion a The said drum may be in connection with the ordinary sending-on post ofli'ce relays a a which, when used, are disposed in the circuit of a split battery 6, the aforesaid circuit being connected with the contact surfaces a of the drum by leads 6*. Condensers b of suitable capacity are arranged across the cont-act between the tongue a and the contact surfaces a of the drum. From the mid point of the battery I) a lead is taken to a direct writer or recording instrument 0, thence through the lead b and the reaction circuit 0 to the tongue a of the relay. The reaction circuit- 6 is a divided circuit, containing in one arm a noninductive resistance 6 and in the other arm an inductive resistance 6 and the auxiliary coil (5 wound on the relay coil a. By suitable adjustments of the coils e and 0 it is possible to determine the magnitude of the current wave through the coil cl, as well as its time-period and shape. It is thus possible to adjust accurately the magnitude and the time effect of the counteracting force exerted on the tongue of the relay, when it is moved into or out of contact with one of the contact surfaces of the drum. The sign of the correcting force is always such that its tendency is to move the relay tongue back toward the insulating strip.

I will now proceed to describe the effect on the signals produced by the employment of the methods of working which are the 3, the full line A, represents the form the signals would assume, when a considerable proportion of the slow discharge currents is allowed to pass through the relay in one of the ways described above. The signals I have chosen as an example are C, H, E and A, viz., .-,because in these signals the effect of my invention on reversals, single dots, and several signals following one another of the same sign is well illustrated. It will of course be understood thatthroughout this specification the code referred to is thecable code,

in which the dot is the'resultof a signal of one polarity, and the dashis the result of a signal of the opposite polarity, there being however no distinction'between the lengths of these signals. In the same figure, the vertical lines B, represent the magnitude of the counteracting force on the tongue of the relay, produced by the current in the reaction circuit hereinbefore described. X represents the insulating portion of the drum, or the no-mans-land as it is sometimes called. P Q, represent the contact surfaces. The dotted line D represents the actual curve traced by the tongue on the drum, and is the resultant of the curve A and the counteracting force represented by the vertical lines B. At the point marked 1, on the curve A a negative signal is just beginning to arrive at the receiving end of the line. At the point 2, the tongue has passed on to the contact surface Q of the drum, and the counteracting force, represented by'the line B does not immediately assert itself, owing to the self induction in the reaction circuit but allows an amplified movement of the tongue to the maximum extent as indicated by the point 3, on the curve A, at which point, the arrival current begins to decrease. At the point 4 the reaction current is equal in value to the arrival current and, consequently, the tongue of the relay has been returned to its zero position. Owing, however, to the fact that the signal under consideration is being followed. by a reversal, the arrival current rapidly decreases, as shown, while the reaction current (although the tongue is now on the no-mans-land) continues momentarily to flow. At this moment, therefore, the reaction current is the stronger, and carries the tongueon to the other contact surface P, of the drum and brings the tongue to the point 5 on the contact surface 1?. The current in the reaction circuit now changes sign and brings the tongue to the point 6 on the contact surface Q. The reaction current then again changes sign and brings the tongue to the point 7 on the contact surface P but as the current from the cable, represented by the thick line A, at that point, is of the same sign, it opsubject of this invention. Referring to Fig. l poses the reversal but allows the tongue to move to the middle of no-mans-land at the point 8.

It will be seen that, in a series of reversals, such as occur in connection with the letter C provided the speed of signaling is high enough, only the first and last of such reversals arrive. The intervening reversals are wiped out but not so the beginning and the end signals due to the result of their being only partially neutralized by a single following and preceding reversal respectively. Under these conditions the current from the cable can start and stop the current inthe reaction circuit Which operates to put in the reversals as though they had actually arrived from the cable.

In the case of a combination of signals of the same polarity, as in the letter H, the curbing of these signals having been reduced as aforesaid, the current from the cable will accumulate or rise to a point indicated at 9, but as the reaction circuit is opposed to this as represented by the line B, the movement of the tongue on the drum will be according to the curve indicated by the dotted line at the point 10; on the current falling to the point 11, the reaction circuit brings the tongue on to the insulated portion X or no-mans-land, of the drum, at the point 12, representing a space between the signals as is the case at the point 8 between C and H. In the case of a single signal of the same polarity as the last signal following this space as in the case of the letter E, the current from the cable will rise to the point 13 on the curve but not so high as in the combination of signals representing the letter H. The effect of the reaction circuit in this connection will be to bring the curve to the point 14, on the insulating portion X representing another space. In the case of the combination of signals of different sign as in the letter A, the reaction circuit will assist the current to make the signaling contacts at points 15 and 16, bringing the tongue promptly back to the insulating portion of the drum at the point 17.

The advantages of this method of working will now be obvious, for it is possible to obtain signals of much greater amplitude than hereto-fore and still retain perfect definition. The practical result of this is that it is possible to largely increase the rate of signaling with a given cable.

It will be found that there is no difficulty in so adjusting the constants of the reaction circuit, as to give the best results, especially if the resistance, in one arm, and the inductance in the other arm, are made so that they are conveniently and readily adjustable. In order that there may be no difliculty in carrying the invention into effect, it may be stated, by way of example, that on a cable of say 32KB such as that between Gibralter and Porthcurnow the magnetic bridge m may have an inductance of 7.32 henries, while the resistances m and m may each have a value of 1 ohm. The-receiving condenser a may have a capacity of about 80 microfarads, while the condenser 0 may have a capacity of 7 microfarads. The condensers Z2 may each have a capacity of 4: microfarads. Each half of the dry battery I) may be composed of 4 dry cells. The resistance of the direct writer or sending 0n instrument 0 may be 500 ohms. The resistance 6 may be of about 20 ohms and the inductance of 6 may be of about 1.8 henries. The resistance of the coil (Z may be about 60 ohms.

It will of course be understood that the diagrams herein referred to which are of a theoretical character are intended as eX- amples of the manner of applying the invention and for the purpose of explaining the invention in connection with submarine telegraphy. Also that although in the foregoing an example of the application of the invention to a duplex system of telegraphy is illustrated and described, the invention may be readily applied in connection with other systems in which the cable code is employed.

What I claim and desire to secure by Letters Patent of the United States is 1. In a system for receiving signals from a cable in cable code the combination with a receiving instrument of means for enabling the discharge currents to be utilized to give amplitude to the signals and a suitably adjusted reaction circuit for modifying such signals to receive increased definition.

2. In a system for receiving signals from a cable in cable code the combination with a relay of a series blocking condenser, a re sistance shunting such condenser, a magnetic shunt across said relay, a resistance in series with such shunt and a reaction circuit which acts diiferently upon the three classes of signals, namely, reversals, consecutive signals of the same sign, and single signals whereby it is possible to utilize the discharge current from the cable and at the same time secure increased definition in the signals.

3. In a system for receiving signals from a cable in cable code the combination with a relay of means for enabling the discharge currents to be utilized to give amplitude to the signals and a suitably adjusted reaction circuit for modifying such signals to receive increased definition.

4:. In a system for receiying signals from a cable in cable code the combination with a receiving instrument of a series blocking condenser, a resistance shunting such condenser, a magnetic shunt across said receiving instrument, a resistance in series with &

such shunt and a reaction circuit which alcts cliiierently upon the three classes of signals, namely, reversals, consecutive signals of the same Sign, and single signals whereby it is possible to utilize the discharge current from the cable and at the same time secure increased definition in the signals.

In testimony whereof I hlfiix my signature Witnesses:

T. SELBY WARDLE, WALTER I. SKERTEN.

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