US2029071A - Telegraph signaling apparatus - Google Patents

Description

Jan. 28, 1936. v -r 2,029,071

TELEGRAPH SIGNALING APPARATUS Filed Dec. 15, 1932' 5 Sheets-Sheet -1 Fig.1.

2 9 4 11 1s 6 15 I 6 I h H M U s a 5 9 d e P i I I 1 8 a 10 12 5 14 7 I/VVENTOR A TTORNE Y Jan. 28, 1936.

H. V. HlGGlTT TELEGRAPH SIGNALING APPARATUS Filed. Dec. 15, 1932 A CHANNEL v M Q 5 Sheets- Sheet 2 INVENTOR HT TORNE Y Jan. 28, 1936.

TELEGRAPH SIGNALING APPARATUS HIGGITT Filed Dec. 15, 1932 BCHANNEI.

ORB

. 5 Sheets-Sheet 3 AcHA/wa Jan. 28, 1936. H. v. HIGGITT TELEGRAPH SIGNALING APPARATUS 5 Sheets-Sheet 5 Filed Dec. 15, 1932 Fig. 18.

Harv- Vernon H 45) OLL.

fiTTUAA EV naling interval.

Patented Jan. 28, 1936 PATENT OFFICE TELEGRAPH SIGNALING APPARATUS Harry Vernon Higgitt, London, England, assignor to Cable and Wireless Limited, a British com- Application December 15, 1932, Serial No. 647,454 In Great Britain December 24, 1931 12 Claims. (01. 178-88) This invention relates to telegraph signaling apparatus and particularly to receiving apparatus for use in signaling with what are now known as double current cablecode signals. Such signals are produced by representing the dot, dash and space by causing difierent electrical conditions and particularly marking and spacing currents to persist for different fractions of a complete sig- The method 'of signaling by the use of double current cable code signals is set forth in the specification of British Patent No. 294,715 and the preferred method described in that specification consists in representing a dot scribed in that patent specification. Again in the specification of British Patent No. 328,945 other methods for sending and receiving signals in that code and a mechanical apparatus for use in carrying out such methods are set forth and claimed. In United States application Serial No. 618,360 filed June 20th, 1932, now Patent No. 1,925,756, issued Sept. 5, 1933 to H. V. Higgitt, apparatus is described including automatic switch for sending signals by the double current cable code in two or more channels. Alternative forms of double current cable code signals are described in the specification of British Patent No. 294,715 and although the form of double current cable code signals described above is the preferred form, the present invention is not limited to receiving apparatus for use with that preferred form.

It is the object of the present invention to provide improved means for dealing with double current cable code signals at the receiving station. Thus, according to the present invention, receiving mechanism is provided which includes switching devices for preparing circuits to be completed for predetermined brief intervals of time definitely related to the signaling intervals so that if during a brief interval of time when, for example, the circuit allocated to dot impulses is prepared for closing, a receiving relay is closed on a particular one of its contacts, the prepared circuit is actually completed through that contact and the current flowing is employed to register a riot in the receiving apparatus, for example, by actuating a perforator to perforate a tape representing a dot, or a retransmitter, or for example, to retransmit a dot by ordinary cable code. In other words, two circuits are prepared alternately at difierent times in readiness to record the reception of any two predetermined signalsout of three signals commonly termed dot, dash and space. Whether or not the circuits would be made to be actuated both by marking current or both by spacing current or again one by marking'current and the other by spacing current would depend upon which mode of double current cable code was used. Further, the mode used would determine which two of the three signals dot, dash and space woud be recorded by the two circuits respectively.

As an example of the adaptability of this invention to the alternative modes of double current cable code, the particular mode may be considered in which a dot is represented by 50 per cent marking followed by 50 per cent spacing, dash by 100 per cent marking and space by 100 per cent spacing. In this case, one circuit is prepared to record a space signal at a point one quarter of the way from the beginning of each signal element, being controlled by spacing current, and the other circuit is prepared to record a dash signal three quarters through each element, being controlled by marking current. If neither circuit is operated, a dot will be recorded. There would be no difliculty in adjusting a siphon recorder to operate from such signals. The siphon with no current through the recorder coil, would be adjusted to take up the dot position; the strength of the space-signal current would be made to be such as to move the siphon to the zero position and the strength of the dash-signal current made about double so as to move the siphon to the dash position.

As another example of the application of the present invention to an alternative mode, the case may be considered when a dot is represented by 50 per cent marking 50 per cent spacing, a dash by 50 per cent spacing 50 per cent marking and a space by 100 per cent spacing. In this case, one circuit will be controlled by marking to record dots one quarter through each signal interval and another circuit controlled also by marking to record dashes three quarters through each signal interval.

In the case of the preferred form of double current cable code referred to above, it is convenient for the dot receiving mechanism to be arranged to prepare a circuit at regularly occurring brief intervals on the marking side of the restantially about points three quarters of the way from the beginning of each signal element, and in a similar way, the dash receiving portion of the receiving apparatus is arranged to become effective for brief intervals of time on the spacing side of the received signals, the intervals in this case occurring substantially about points one quarter'of the way from the beginning of each signal element. By means of this arrangement, a space signal consisting of marking current for the first 50 per cent of a signal interval and of spacing current for the other 50 per cent simply produces no effect on the receiving apparatus because at the brief interval of time when the receiver is in a condition to respond to spacing current, marking current has actually passed, while at the brief interval of time occurring at about the middle of the second half of the space signal when the receiving apparatus is in a condition to respond to marking current, it is spacing current which is actually arriving. In the case of a dash which consists of 100 per cent spacing current when the interval occurs at about one quarter the way from the beginning of each signal, the receiver can respond to spacing cur-- rent and spacing current is arriving corresponding to a dash so that a dash is effectively received. Similarly as a dot consists of 100 per cent marking current at a brief interval of time about three quarters of the way from the beginning of the signal, the apparatus is in a condition to respond to marking current and as marking current is being received the receiving apparatus actually and effectively receives a dot.

The circuit which is prepared and actuated when the appropriate current comes in may conveniently contain a condenser which'is charged, and after the brief charging interval is arranged to be discharged through a suitable relay which may for example, cause the actuation of a perforator or similar apparatus and that relay is locked through a maintaining winding until the locking circuit is interrupted by another switching device in time for the relay to be actuated again should the next signal impulse call for that particular relay to be immediately actuated again. The switching mechanism for charging the con-v denser and discharging it through the relay and completing the locking circuit of the relay may be of various types capable of suitable timing. They may for example, be contact springs whose closing is timed by rotary cams or they may be of the distributor type having contact segments;

co-operating with brushes.

Apparatus in accordance with the present invention with suitable elaboration may conveniently be used for the reception and separation of double current cable code signals allocated in rotation to two or more channels as set forth in United States application Serial No. 618,360 referred to above.

A pair of charging switches of either kind referred to above is provided, one for marking current and the other for spacing current, the cir-. cuit for charging either of two condensers being. completed for brief intervals of time spaced relatively as already described. The dot and dash condensers are conveniently common to both channels or to all channels if there are more than two. .Two separate discharging means and relays are used for each channel.

,In order that the invention may be clearly understood and readily carried into effect, some examples of receiving apparatus in accordance therewith will now be described more fully with reference to the accompanying drawings, in which:---

Figure 1 is a diagram illustrating double current cable code signaling;

Figure 2 is a diagram of connections of a receiving apparatus according to the invention, in which rotary distributor switches are employed;

Figure 3 is a'diagram of connections of a form of receiving apparatus according to the invention capable of dealing with double current cable code signals allocated to two channels and employing rotating cam operated switches;

Figure 4 is a diagram of connections very similar to Figure 3, but showing the timing somewhat modified so that the dots and dashes in the output are brought into phase;

Figures 5 to 17 are a series of diagrams illustrating in detail the timing of the different parts constituting the system shown in Figure 4.

Figure 18 is a diagram illustrating a portion of another form of the invention; and

Figure 19 is a diagrammatic showing of a further form.

In. the following detailed description of the drawings, a receiving relay RR is shown having a tongue I movable between two contact stops M, S called the mark and space stops. This relay RR may be operated by signals consisting of current in one direction for marking and the other direction for spacing, or by the well known "single current such as might in efiect be obtained from a rectified carrier current. The relay RR may alternatively be replaced by thermionic valves, or again the relay RR can be omitted provided the circuits are of a form suitable to respond to and differentiate between the incoming marking and spacing conditions, what- 'ever they may be.

Referring'firstof all to Figures 1 and 2 of the drawings, Figure 1 illustrates the form of double current cable code signals which the receiver illustrated in Figure 2 is adapted to receive. The clearest conception is obtained if the curve in Figure 1 is considered to represent the position of the contact tongue I of the receivi g relay RR ,seen in Figure 2. The position of ms tongue is plotted against time, the distances ab, be, cd, and de each representing one signal interval, or the distance between consecutive centre holes. In the signal interval ab, the curve shows how the tongue I moves during the reception of a space, that is to say, marking current is received for 50 per cent of the signal interval as shown at 2 and spacing current for the remaining 50 per cent of the signal interval as shown at 3. Betweenthe points 12 and c, the reception of a dot is shown which consists in receiving marking current for 100 per cent of thesignal interval as shown at 4. Further, between the points and d, the reception of a dash is illustrated consisting in receiving 100 per cent spacing current as. shown at 5. Between the points d and e reception of a further space, as shown att and l is illustrated. In Figure 1, in. each signal interval there is conventionally shown a pair of distributor segments 8, 9, l0, ll, l2, l3, l4, l5. Thesegments 8, l0, l2, and H are shown occupying a short space about a quarter of the way from the commencement of the respective signal interval. The other distributor segments, 9, ll, 13, and I are shown occupying a position about three quarters of the way from the beginning of a signal intervaL, Now if it be assumed that the segments 8; I 0, l2, and I4 are in series with a circuit connected to the spacing contact S of the relay RR in Figure 2 and the segments 9, II, I 3, and I are connected to a circuit in series with the marking contact M of the closed at its marking contact and again no circuit is completed. Thus, for this space signal and for all other space signals no circuit is completed and the receiver is not actuated. Now during the signal interval bc, upon receiving a dot, when a circuit is prepared at segment Hi again the relay RR is not closed at its spacing contact so that no circuit is completed, but when a circuit is prepared at contact H, the relay RR is on its marking contact M and as will be seen more fully in connection with Figure 2, a circuit for charging a condenser 2I is completed. Generally speaking, as regards the dot signals, a condenser allocated to dot signals is charged around about a point three quarters of the way along the signal interval.

Then considering the dash'signal between the points cd in Figure 1, when a circuit is prepared at segment I2 the receiving relay RR in Figure 2 is closed at its spacing contact S and as will be described more fully in connection with Figure 2, a circuit for charging a dash condenser I 9 is completed. Then when a circuit is prepared at segment I3 the relay RR is not closed at its marking contact M so that no circuit is completed at that instant. Generally speaking, in the system illustrated, when receiving dash signals a circuit charging a condenser I9 allocated to dashes is completed at a time about one quarter the way through a signal interval. This explains the principle upon which the present invention is based.

In Figure 2, a simple form of receiving circuit for dealing with one channel and employing rotary distributor switches is illustrated. The distributor segments 9, II, It, I5 and 8, I6, 52, I l, correspond exactly to those shown in Figure 1 and are to be assumed as equally spaced 90 degrees apart around the surface of a drum shown developed between the lines XY-XY. A brush it is swept over segments 9, II, I3, and I5 and a brush I? on the same arm I8 as the brush IE, but insulated from it, sweeps over the distributor segments 8, It, I2, Id. The brush arm I8 may.

be driven, for example, by a phonic motor in step with the signals. The circuits referred to in connection with Figure 1 may now be clearly seen. First of all the brush I l rests upon the segment 8 at that instant at which the relay RR is closed at its marking contact M as will be seen from Figure 1. The circuit through brush It and segment 8 is therefore interrupted at the spacing contact S. The same occurs when the brush II arrives on the segment It] as can be seen with reference to Figure 1. When however, the brush I'I arrives on the segment I2 it will be seen from Figure 1 that the spacing contact S of the relay RR is closed and, consequently, the charging circuit for the dash condenser I 9 is completed from the positive pole of the battery 20 through relay tongue I, spacing contact S, segment I 2, brush II, condenser I9 and returning to the battery 26. In a similar way, the brush I6 is connected directly to the condenser 2I associated with the dot signals and when the brush I6 rests upon the segment 9, I3 or IE, as can be seen from Figure 1, the relay RR is not upon its marking contact M so that no circuit is completed. On the other hand, when the brush I6 rests upon the segment I I the relay RR is closed at the marking contact M, as can be seen from Figure 1. Then the charging circuit for the condenser 2| runs from the positive pole of battery 20 through tongue I, marking contact M, segment I I, brush I6, condenser 2| returning to the battery 20.

The brush I6 also co-acts with dot discharging segments 22, 23, 2t, and 25 while the brush I'I cooperates with-similar discharging segments 26, TI, 28, and 29. If the dot condenser 2| has been charged and then the brush I6 comes into contact with one of the discharging segments 22, 23, 2d, 25, the condenser 2I is able to discharge itself by way of the brush I6, the discharging segment in question the operating winding 30 of the dot output relay CR and back through the conductor ill to the condenser 2 I. Similarly if the condenser I 9 has been charged and the brush I! then comes into contact with one of the discharging segments 28, 21, 28 or 29, a similar circuit is completed for the dot condenser I9, through the winding 32 of the dash output relay 0R It will be noticed that although the pick-up segments 9, II, I3 and I 5 occur at points corresponding to times three quarters the way through each signal interval and the pick-up segments 8, I 0, I2, I41 are located at points corresponding to a quarter the way through the signal interval, the discharging seg ment 22 is in line with the discharging segment 27 and so forth so that, although charging does not take place at the same instant for dots and dashes, discharging does, and by making use of the storage properties of the condenser I ii, the dot and dash outputs at the relays OR and QR are brought into phase or into step.

When the relays CR and OR are actuated at the brushes I6 and III and their respective discharging segments, these brushes need to be released for further duty and cannot therefore remain in circuit long enough to produce ordinary cable code output signals at the contacts 33 and 341 of the relays 0B and CR To overcome this the relays themselves are retained closed through locking circuits in the form illustrated or they may be neutral bias relays which remain in one position until positively restored. In the form illustratedhowever, the dot output relay OR is arranged to be locked up by locking segments 34, 35, 36, and 3? and similarly locking segments 38, 39, Eli, and iii are provided'for the relay OR. The dot locking brush is shown at It and the dash locking brush at GI. These co-operate respectively with the dot and dash locking segments. It will be noticed that the left hand edges of the segments 36, 35, 35, and iii for example, are in line with the left hand edges of the discharging segments 22, 23, 2 1, and 25, but that the segments 36, 35, 36, and 37, extend over a greater width than the discharging segments, in fact, extend so far as to lock up the relays 0R OR to a point at which they must be released for actuation by a fresh discharging segment. The circuit for looking the relay OR is from the positive terminal of the battery 26 through brush ti] and locking segment 36, 35 or 36, through locking winding I12 of the relay OR and back to the negative of the battery 20. It will be noticed that this circuit also passes through a back contact 3 so that it is only completed when this contact has been closed by energization of the actuating winding 30. The dash output relay OR has a similar locking winding M and back contact 45 and its circuit is similarly completed through brush II and segments switch 5|.

37, 38, 39. The result produced by this receiving circuit that at relay contacts 33, 34 there is an ordinary cable code output. The contact 33 can obviousiy control the dot mechanism of a perfora= tor and the contact 3% the dash mechanism or they may controlthe corresponding mechanism of a retransmitter.

In Figure 3, a more complicated receiving system is shown for dealing with signals allocated to two channels. Furthermore, in Figure 3 the switches, instead of being rotary distributor switches, are cam-operated contacts. The relay RR is the receiving relay as in Figure 2 and there is a dot charging switch consisting of two switches t6, 3? in series and similarly the dash charging switch consists of two switches 68, 39 in series. The purpose of using two switches in series at these points is to enabie the actual time of con= tact to be reduced as desired, by the use of separately adjustable switches. It will be seen that exactly as in Figure 2, a circuit is prepared through a dot condenser 2i and a dash condenser l9 periodically for brief intervals of time. The switches 66 and M in this case make one revolution for every two signal intervals; that is because the apparatus is dealing with two channels. The time of closing the switches 36, d1, 58, and G3 is shown by the arcs in heavy lines so that the g the contact segments of switches 46 and 41 are at right angles to those of switches 38 and 59 so that the switches 43 and t1 prepare the charging circuit of the condenser 2! for brief intervals of time about three quarters of the way through each signal interval. Then exactly as in connection with Figure 2, the completing of the condenser circuits and the charging of the condensers depend entirely whether at the appropriate instant, the tongue l of the relay RR is on the marking contact M or on the spacing contact S. It will he noticed that the dot and dash condensers 2i and I9 are common to both channels or to all channels if there are more than two. There are, however, two separate discharging means and relays for each channel. The channels may conveniently be referred to as the "A channel and B channel. On the A channel there is a dot discharging switch 50 and on the 13 channel there is a dot discharging These carry out the same functions as the dot discharging segments 22, 23, 2d, and in Figure 2, but theyhischarge alternately as can be seen by the time of contact indicated by the arc heavy lines at 50 and 5|. There is also a dash discharge switch 52 for the A channel and a dash discharge switch 53 on the B channel. These discharge alternately, but in the intervals between the dot discharges. If the condenser 2! has been charged and the switch 50 closes, the condenser 2| discharged through the actuating winding A of the dot output relay GRA of the A channel. If, however, when the condenser 2|, is charged, the switch 5| next closes, the condenser is discharged through the winding 30B of the dot output relay ORB of the B channel. Similarly, for the dash condenser I9, if it has been charged and the switch 52 next closes, the condenser is discharged through the actuating winding 32A of the dash output relay ORA and finally, if when the condenser i9 is discharged, the switch 53 next closes, the condenser I19 is discharged through the actuating winding 32B of the dash output relay ORB on the B channel. The four output relays have locking circuits exactly as in Figure 2 completed respectively through back contacts 33A, 45A, 43B, 353. When these contacts are closed the locking circuit is completed through locking switches 55, 55, 56, and 51 which correspond to the locking segments 34 to 39 in Figure 2. The actual time for which these locking circuits are closed is indicated by the arcs in heavy lines at 53, 55, 56, and 51. The main con tacts of the output relays 33A, 34A, 33B, and 36B are shown as closing the circuit of the perforator 58A or 583.

The timing of the apparatus will be dealt with more fully after referring to Figure 4, but it will be seen that, generaliy speaking, the system operates exactly as described in connection with Figure 2,.except that the discharging means on the A channel and the discharging means on the B channel come into action alternately so that the signals actuating the receiving relay RR are sorted out and the two channels separated so as to operate the perforators 58A and 583 in proper sequence. The discharging and locking switches are driven at the same speeds as the charging switches and may, of course, be actuated in step with the signals by a phonic motor.

In connection with Figure 3 it will be noted that the discharge switches producing the dot and dash output are timed so that the dots and dashes are not in phase. This can be seen, for example, by comparing the 'arcs shown in heavy lines in the switches 50 and 52. The system illustrated in Figure 4 is identical with that shown in Figure 3, except that the timing of the discharging and locking switches has been changed in' Figure 4 to bring the dots and dashes of the output as nearly into phase as possible. In Figure 4, the parts have been numbered exactly as in Figure 3 and the operation can be readily followed. If the are shown in heavy lines at the discharge switch 50 be compared with the are shown at the dot charging switches 45 and 61, bearing in mind that 53 is a dot discharge switch, it will be seen that the time of storage of the dot impulses in the condenser 2! has been reduced to a minimum. On the other hand, by comparison with the arc shown in heavy lines in the dash discharge switch 52 with the arcs in the dash charging switches 48 and 59, it will be seen that the dash impulses received through the spacing contact S of the relay RP; are stored in the dash condenser [9 for the maximum period. The result is as can be seen, for example, by comparing the time of contact indicated by the heavy arcs in switches 50 and 52 that the dot and dash output impulses are practically in phase or in step.

The systems illustrated in Figures 3 and 4 can probably be more clearly appreciated by studying the timing diagrams shown in Figures 5 to 17. These diagrams correspond to the switch settings shown in Figure 4, but the difierence between the settings in Figures 3 and 4 can be easily seen.

Figure 5 corresponds to Figure l and shows an example of signals; the alternate signal intervals being allocated to one channel. Thus, the signal intervals fg and his and Zm are allocated to the A channel, while the intervening signal intervals gh and 1d are allocated to the B channel as indicated by the lettering above Figure 5. By comparison with Figure 1, it will be seen that Figure 5 represents a space in the A channel followed by a dot on the B channel and then a space on the A channel, a dash on the B channel and a space on the A channel. Figures 6 to 1'7 are projected from Figure 5 in the sense that the instants of time indicated in Figure 5 are the same as the instants of time in the other figures lying on the same vertical lines. Thus, Figure 6 shows two sets of rectangles indicating overlapping of the contacts of the dot charging switches or pick-up switches 46, 41 in Figure 4. The actual time of charging or pick-up is the overlapping time and this is shown by the small rectangles in Figure 8. In a similar way Figure 7 illustrates the overlapping contacts of the dash charging switches 48 and 49 in Figure 4 and the small rectangles in Figure 9 show the actual time of charge of the dash condenser. l9. Figure 10 shows the actual times of discharge of the dots on the A channel and therefore represents the times of closure of the switch 58 in Figure 4. The dotted arrows connecting Figure 8 with Figure 10 merely connect the switch segments which are effective on the same output relays. In this case it is a question of the dot output relay on the A channel, that is the relay ORA in Figure 4. The dot discharge on the B channel is shown in Figure 14 and it will be noticed how the times of closure occur between the times of closure on the A channel as shown in Figure 10. Figure 12 shows the timing for the dash discharge switch 52 on the A channel and Figure 16 the timing of closure of the dash discharge switch 53 on the B channel. In each case the charging or pick-up timing is shown linked to the discharge timing corresponding to it by arrows in dotted lines. A comparison of Figures 10 and 12 or again of Figures 14 and 16 shows how the dot charges in the condenser 25 have been retained for the shortest possible time and the dash storage in the condenser 119 has been retained a maximum time in order to bring the times of discharge on the dots and dashes almost in phase or in step. The dotted arrows emphasize this. The dot discharge timing rectangles being very little after the corresponding charging rectangles, while in the case of the dashes there is a very considerable delay after the charging or pick-up rectangles before the discharging rectangles commence. In the example illustrated the time of discharge in each case is 20 per cent of the time represented by the distance between centre holes of a channel. Figures 11 and 13 show the times during which the locking circuit is maintained for the dot output relay ORA, or the dash output relay ORA on the A channel. Figures 15 and 17 show the time of maintaining closed the locking circuits of the dot and dash output relays ORB and ORB on the B channel. Each locking circuit is kept closed,

it will be seen, for aperiod equivalent to 80 per cent of the distance between successive centre holes on the channel.

It is possible as an alternative for the dot and dash relays to be put in series with the respective condensers so as to be actuated by the charge of the condensers, but it would not in general be possible to make the charging interval so short under these conditions, because of the inductance of a relay of the type usually employed. Furthermore, in that case, it would not be possible to adjust the phase relation between the actuation of the dot and dash relays. This phase relation depends upon requirements. Thus, when actuating automatic perforators or the well known siphon recorder it will usually be desirable to have the dots and dashes in phase, but when the signals are to be retransmitted after suitable manipulation in the form of double current cable code signals, it may be desirable to provide a certain phase difierence between them.

The switches in the receiving mechanism according to the present invention, must be kept in synchronism with the incoming signals so that the dot and dash relays are controlled by the correct portions of the signals. Any means such as the use of phonic motors for obtaining and maintaining synchronism may be employed. The preferred form of double current cable code signaling already referred to above is particularly suitable for use in conjunction with a synchronizing system in which impulses are initiated by the ends of the signals which actuate mechanism for applying a suitable speed or phase correction. A correction relay controlled by the in- Y coming signals directly or from the line relay may be caused to charge a condenser when on the spacing contact and to discharge it when on the marking contact. The discharge impulses could be used to efiect synchronism in the manner set forth in the specification of British Patent No. 238,622 in which they cause speed corrections to be made momentarily in the motor driving the mechanism.

The use of double current cable code, particularly when the signals are divided amongst two or more channels enables a substantial degree of secrecy to be obtained when used for wireless telegraphy, since the signals are not readable until they are passed through suitable synchronized receiving mechanism. The degree of secrecy may be increased by varying the speed. Thus, for example, the speed might be varied in a predetermined manner between 95 and 105 words per minute if the mean speed required were 100 words per minute. The speed of the mechanism would then be caused to vary in a corresponding manner and such an arrangement would not be difficult to anyone knowning the requirements, but would be very diflicult to be dealt with by an unauthorized receiver of the signals. A simple way in which the variation in speed may be effected is by interposing an elliptical spur gear between the motor rotating at uniform speed and the receiving mechanism, although any other well known and approved form of mechanism for producing variable speedrotating movement may be employed.

Secrecy could also be increased by dividing the signals amongst two or more channels in some predetermined sequence instead of in regular rotation. For example the signals may be divided amongst two channel's A and B in a sequence represented by AAB-AAB In this way the speed of the A channel is made twice that of the B channel, but reception of such signals may be carried out conveniently by employing apparatus disclosed with reference to Figure 2 of the annexed drawings employed in conjunction with apparatus for handling uneven speed channels, for example, as disclosed in British Patent No. 287,229, particularly the apparatus illustrated in Figure 7 of the drawings annexed to the complete specification of that British patent. The armatures 33 and 34 of the outgoing relays in Figure 2 of the drawings annexed to the present application would be arranged to control the apparatus disclosed in British Patent No. 287,229.

Figure 18 shows a further type of circuit arrangement comprising two thermionic valves or electron discharge tubes which replace the relay RR in Figure 2. The conductors 64, 65, 66 go to the positive terminal of battery 20 and to the distributor segments 8 and 9 respectively. The

line is shown at L and when ppsitive potential is on it, current flows from line to earth through the two resistances It so that the grid of the tube 62 is positive and that of grid 63 is negative so that the former will be conductive and the latter non-conductive. The result is that when brush it in Figure 2 makes contact with any one of the segments 9, ii, i3, i condenser 2i is charged, while the brush ll cannot charge condenser i9. When, however, the line L is at negative potential, the reverse is the case, the tube 63 then being conductive and allowing of the charging of condenser i 9 when brush i l' touches any one of segments 8, i0, i2, Ml.

Figure 19 shows another modification of Figure 2 arranged for reception direct from line Without the provision of a receiving relay RR as shown in Figure 2. In addition to omitting relay RR, the relays 0R OR in Figure 19 differ from those in Figure 2 as they are polarized. Thus, when the line L is positive, condensers 2i and i Q will be charged alternately but positively and the condensers are discharged through the windings of relay CR and OR respectively. These windings are connected, however, in such a way that the positive discharge onlyoperates relay 0R When the line is negative, the condensers 2i and i9 will also be charged alternately but in this instance negatively. They both discharge through segments 22 and 2? but the negative discharge only operates the relay 0R Brushes elil and M control locking circuits as described in connection with Fi ure 2 1. In a telegraph signaling apparatus for receiving double current cable code signals, employing three kinds of signals constituted by two different electrical conditions persisting for different portions of a signaling period, the combination of a receiving device having two contacts actuated in accordance with the difierent electrical conditions forming the signals and a pair of switching devices actuated regularly at the rate of occurrence of the signaling periods, each comprising coacting contact members so relatively located that, alternately during each signal period, said switching devices prepare respectively circuits, each of which includes one of the two contacts of said receiving device and is allocated to the reception of one of the said three kinds of signals employed in the code.

2. In a telegraph receiving apparatus for receiving double current cable code signals of the type set forth, the combination of a receiving relay having two contacts actuated in accordance with marking and spacing currents forming the signals and a pair of switching devices driven so as to be regularly operative at the rate of occurrence of the signaling periods, each comprising coacting contact members so relatively located that said switching devices prepare circuits respectively each including one of the two contacts of said receiving relay, during the first half and the second-half of each signaling period respectively.

3. In a telegraph receiving apparatus for receiving double current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for different portions of a signaling period, the combination of a receiving relay having two contacts actuated in accordance with marking and spacing currents forming the signals, a pair of condensers allocated respectively to two of the three kinds of signals employed in th; code anda pair 01 switching devices driven so as' to be regularly operative at the rate of occurrence of the signaling periods, each comprising coacting contact members so relatively located that said switching devices prepare two charging circuits each of which includes one of said condensers and one of the two contacts of said receiving relay so that said condensers are charged selectively in accordance with the signals received.

4. In a telegraph receiving apparatus for receiving double-current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for different portions of a signaling period, the combination of a receiving relay having contacts actuated in accordance with marking and spacing currents forming the signals, a pair of condensers allocated respectively to two of the three kinds of signals employed in the code, a pair of switching devices driven so as to be regularly operative at the rate of occurrence of the signaling periods, each comprising coacting contact members so relatively located that said switching devices prepare charging circuits each of which includes one of said condensers and a contact of said receiving relay so that said condensers are charged selectively in accordance with the signals received, and a further pair of synchronously actuated switching devices for respectively completing discharging circuits for said condensers.

5. In a telegraph receiving apparatus for receiving double-current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for different por-- tions of a signaling period, the combination of a receiving relay having contacts actuated in accordance with marking and spacing currents forming the signals, a pair of condensers allocated respectively to two of the three kinds of signals employed in the code, a pair or synchronously actuated switching devices organized to prepare alternately charging circuits each including one of said condensers and a contact of said receiving relay so that said condensers are charged selectively in accordance with the signals received, a further pair of synchronously actuated switching devices for completing respectively discharging circuits for said condensers and a pair of electromagnets for registering, recording or retransmitting the signals, each energized by the discharge current from one of said condensers.

6. In a telegraph receiving apparatus for receiving double-current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for different portions of a signaling period, the combination of a receiving relay having contacts actuated in accordance with marking and spacing currents forming the signals, a pair of condensers allocated respectively to two of the three kinds of signals employed in the code, a pair of synchronously actuated switching devices organized to prepare alternately charging circuits each of which includes one of said condensers and a contact of said receiving relay so that said condensers are charged selectively in accordance with the signals received, a further pair of synchronously actuated switching devices for completing respectively discharging circuits for said condensers, a pair of electromagnets each furnished with an operating winding and a locking winding in circuit with a contact closed by the electromagnet, said operating windings being respectively connected in the discharge circuits from said condensers and a third pair of synchronously actuated switching 76 devices in circuit with said locking windings for pendently of their operating windings.

7.11 a telegraph receiving apparatus for receiving double-current cable code signals, the three kinds ,of signals of which arerepresented respectively by'marking current of 100 per cent duratioi'rspacing currentof 100 per-cent'duration andmark-ingcurrent of=50 percent duration followed by spacing current of 50 per cent duration, the combination of a receiving relay having marking and spacing contacts closed respectively .when said receiving relay receives marking and spacing currents forming the signals, a switch- 7 ,ing mechanism, synchronously operated in step with the 'signals,rallocated to the first mentioned kind of signal and organized to prepare a circuit includingthe marking contact of said receiving relay at regularly occurring times about three quarters of a signal interval from the commencement of each signal intervaland a second switching device synchronously operated in step with the signals, allocated to the second mentioned kind of signal and organized to prepare a circuit including the spacing contact of said receiving relay at regularly occurring times about one quarter of a signal interval from the commencement of each signal interval.-

"8. In a telegraph signaling apparatus for receiving and separating double-current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for different portions of a signaling period, said signals being allocated in rotation to a plurality of channels, the combination of a receiving relay having contacts actuated in accordance with marking and spacing currents forming the signals, a pair of condensers common to the diiIerent channels and allocated respectively to two of the three kinds of signals employed in the code, a pair of synchronously actuated switching devices also common to the different channels and organized to prepare alternately charging circuits, each of which includes one of said condensers and a contact of said receiving relay so that said condensers are charged selectively inaccordance with the received signals of the two kinds mentioned, and a further pair of synchronously actuated switching devices allocated to each of the channels for completing discharging circuits for said condensers respectively, each discharging circuit being allocated to one of the two kinds of signals mentioned in one of the channels.

9. In a telegraph signaling apparatus for receiving and separating double-current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for difierent portions of a signaling period, said signals being allocated in rotation to a plurality of channels, the combination of a receiving relay having contacts actuated in accordance with marking and spacing currents forming the signals, a pair of condensers common to the different channels and allocated respectively to two of the three kinds of signals employed in the code, a pair of synchronously actuated switching devices also common to the difi'erent channels and organized to prepare alternately charging circuits each of which includes one of said condensers and a contact of said receiving relay so that said condensers are charged selectively in accordance with the received signals of the two kinds mentioned, a further pair of synchronously actuated switching devices allocated to each of the channels for completing discharging circuits for said condensers respectively, each discharging circuit being allocated to one of the two kinds of signals mentioned in one of the channels and a signal-translating device included in each oi said discharging circuits. 3

. 10. In a telegraph signaling apparatus for receiving and separating double-current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for difierent portions of a signaling period, said signals being allocated in rotation to a plurality of channels,.the combination of a receiving relay having contacts Iactuated in accordance with marking and spacing currents forming the signals, a pair of condensers common to the different channels and allocated respectively to two of the three kinds of signals employed in the code, a pair of synchronously actuated switching devices also common to the different channels and organized to prepare alternately charging circuits, each 01 which includes one of said condensers and a contact of said receiving relay so that said condensers are charged selectively in accordance with the received signals of the two kinds mentioned, and a further pair 01' synchronously actuated switching devices allocated to each of the channels for completing dischargingcircuits for said condensers respectively, each discharging circuit being allocated to one of the two kinds of signals mentioned in one of the channels. said last-named pair of synchronously actuated switching devices being so timed as to bring the signals of the two kinds substantially into phase in each channel.

11. In a telegraph signaling apparatus for receiving double current cable code signals, em-- ploying three kinds of signals constituted by two diflerent electrical conditions persisting for different portions .of a signaling period, the combination or a telegraph line adapted to deliver the g double current cable code signals, and a pair ofswitching devices actuated regularly at the rate ofoccurrence oi! the signaling periods, each comprising coacting contact members so relatively located that, alternately, during each signaling period, said switching devices prepare respectively circuits which become operative in dependence upon the incoming double current cable code signals, each of said circuits efiecting the reception of one of the said three kinds of signals employed in the code.

12. In a telegraph signaling apparatus for receiving double current cable code signals employing three kinds of signals constituted by marking and spacing currents persisting for different portions of a signaling period, the combination of a telegraph line delivering the double current cable code signals, and a pair of switching devices actuated regularly at the rate of occurrence of the signaling periods, each comprising coacting contact members so relatively located that, alternately, during each signaling period, said switching devices prepare respectively circuits which become operative in dependence upon the incoming double current cable code signals, each of said circuits eflecting the reception of one of the said three kinds of signals employed in the code.

HARRY VERNON mcerrr.

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