US2095144A

US2095144A - Telegraph signaling apparatus

Info

Publication number: US2095144A
Application number: US13771A
Authority: US
Inventors: Masson Albert Henry
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-04-10
Filing date: 1935-03-29
Publication date: 1937-10-05
Anticipated expiration: 1954-10-05
Also published as: GB430453A

Description

TELEGRAPH S IGNAL ING APPARATUS Filed March 29, 1935 2 Sheets-Sheet l ALBERT HENRY IVA'SGOA/ Oct. 5, 1937. A. H. MASSON TELEGRAPH SIGNALING APPARATUS 2 Sheets- Sheet 2 Filed March 29, 1935 lll lllll l l l 1 ll 1111 l IWII I II III as RQJ QQW in to". ova/ A:

Patented Oct. 5, 1937 Albert Henry Masson, Maranhao, Brazil Application March 29, 1935, Serial No. 13,771 In Great Britain April 10, 1934 13 Claims.

This invention relates to telegraph signaling apparatus and more particularly to apparatus for the reception of telegraph signals.

In order to overcome interference in telegraphy, and particularly the effects of atmospherics or fading in Wireless telegraphy-circuits, it is well known to arrange for signals to be repeated from a transmitting station after certain time intervals and for the repeated signals tobe superimposed upon the first transmission of the signal so that the original transmission and the repeated signals are compared at a receiving station. The object of the present invention is, in the first instance, to render it unnecessary in such repetitions ystem's to provide more than one repeated signal, although the invention may be applied to obtain improved results with more than one repetition of the signals.

The invention is applicable to the reception of signals transmitted on any code, such as the ordinary cable code or the five-character code but ithas special application to the reception of double current cable codesignals, that is to say, signals sent by the Morse code in which the signals consist of electrical conditions which are made to persist for various time intervals. The usual practice in double current cable code, an example of which is setout in Patent No. 2,029,- 1'71, filed 15th December1932, issued Jan. 28, 1936, is to represent a dot by marking current having a duration of 100 per cent of a signaling interval, a dash by spacing current having the same duration and a space by marking current lasting for 50 per cent of a signaling interval followed by spacing current lasting for the remainder of the signaling interval. The present invention enables such signals to be transmitted in one channel and the signals to be repeated after a predetermined time interval in the intervals between the signals ofthe original transmission which actually form the second channel.

Generally, the system of the present invention presents the following four operating functionsz' first, when the two successive incoming signals are free from distortion the apparatus records the received signal upon a tape, as by means of a perforation; second, if the second signal is unidentifiable due to fading, etc., the apparatus will record the first and properly received signal; third, the apparatus functions as in the second condition if the first signal is mutilated, but the second signal is undistorted; and fourth, if both the first and second signals are received in a mutilated and an unidentifiable condition, the apparatus will causethe sign-a1 recorder to be obliterated so that the record cannot erroneously show a dot or a dash.

It is-known in repetition systems to store the original transmission at the receiving station until the repeated signals arrive so that the original transmissionand the repeated transmission can be compared simultaneously. In accordance with the present invention, however, it is necessary to store the second or repeatedtransmission for a relatively short time because it is desired to allow both the signals of the original trans mission and of the repeated transmission to act upon an automatic apparatus which will control the obliterating of the signals and it is necessary to store both transmissions so that this apparatus hasan opportunity to act ondistortecl signals before the latter pass to the receiving apparatus.

Thereceiving apparatus may consist of an automatic scrutinizing device based on the principle of that set forth in British patent specification No. 286,365 and its effect may be that when mutilated or distorted signals arrive, over the period controlled by the device, it causes impulses of a type generally different from the fundamental signals of the code to be stored on both channels. The storage system may be of any kind such as condenser storage, electromagnetic storage or mechanical storage in whichthe stored signals are represented by pins or similar movable elements'which can be caused to take up one of two or more positions. When condenser storage is employed,the obliterating charges may be charges all of one sign toqwhich all the condensers are charged over the predetermined period. The charges in thev condensers on the first transmission channel are stored for a long period before being discharged and those on the second channel for a relatively short period, but when the condensers thus charged are discharged, they render the relays or otherreceiving apparatus on that particular channel ineffective for the number of signal intervals for which the signals are to be obliterated, so that in each case the other channel takes charge of that time. A device of the kind referred to, sensitive to distortion. of the signals, can be employed in dealing with lightning or other brief atmospheric disturbances, but disturbances of longer duration, such as those due to fading, changing of a line or insertion of a wrong plug, may be dealt with by a similar device controlled by failure of the incoming signal current to change over from space to mark. These obliterating devices may be step-by-step devices which, after a" predetermined number of steps, cause positive charges to be passed to all the condensers.

Control switches may be provided so that when there are no effective disturbances, the signals are no longer repeated but the two separate channels are available for operating on two separate transmitted messages.

In order that the invention may be clearly understood and readily carried into effect, a telegraph receiver for double current cable code signals arranged in accordance with the invention will now be described more fully with reference to the accompanying drawings, in which:

Fig. 1 is a circuit diagram showing the mode of connection of the receiver.

Fig. 2 is a diagram showing the operation of the device in connection with true and distorted signals.

The signals from the line L are received on a receiving relay RR, which functions in the same way as that illustrated in Figures 2, 3 or 4 of the drawings accompanying patent application Serial No. 647,454, now Patent No. 2,029,071, issued Jan. 28, 1936. The upper tongue I of this relay deals with the signals on both channels. In the conductors 2, 3 from the mark contact M and the space contact S of this relay, there are contacts 4, 5 which are closed by cams 6, 1 for about 10 per cent of each signal period. These correspond to the

charging contacts

46, 41, 48, 49 in Figures 3 and 4 of the drawings accompanying Patent No. 2,029,071. It will be noted that the raised parts of the cam 6 are set at right angles to the raised parts of the cam I but both are driven synchronously with the signals in such a way that the contact 4 is closed for receiving dots at a point about three-quarters the way through each signal period as indicated at 6 in Fig. 2, which is more fully described below, and the contact 5 for receiving dashes about a quarter the way through each signal period as indicated at 1 in Fig. 2, and described in the above-mentioned prior patent specification. The dot signals thus picked up are applied to a charging brush 0 and the dash signals thus picked up are applied to a charging brush 0 of a rotary distributor switch. This rotary distributor switch is to be operated at the same speed as the transmitting distributor and to be held in synchronism'therewith by any of the several well-known methods of correcting from line signals well recognized in the art of telegraphy. The segments of this switch are arranged in two rows or banks, the upper bank n n n being allocated to dot signals and the lower bank m m m being allocated to the dash signals. It will be appreciated that these segments are illustrated as a development of segments set on a rotary drum and the segment n in the upper row appears at both ends just as does the segment m in the lower row: also while sixteen segments are shown in each row, in practice, there will commonly be a considerably larger number of segments to each row. The number of segments is arranged so that when the rotary drum is running at the normal speed for reception, the time between the brush (1 coming into contact with a particular segment and subsequently the brush 9 coming into contact with that segment is equal to the time which elapses between the original and repeated transmission of a given part of the signal. This period is chosen as far as possible so that a signal which is lost, or at least badly mutilated during one transmission due to positive static, that is interference, or due to negative static, that is fading, will not be lost or mutilated during the other transmission. It will also be noted that the segments of the upper row are staggered with respect to those of the lower row, each being spaced exactly half way between two of the segments of the lower row; all of the segments n n n and m m m are each connected to a storage condenser. The dot storage condensers appear at h 71. h the condenser h is shown duplicated in the drawings for the sake of clearness. Similarly the dash condensers are shown at 70 W, 10 the condensers being directly connected as shown to their respective segments of the distributor switch and their opposite plates being connected through the conductor 8 to the negative pole of the battery B.

In an alternative arrangement the segments of the distributor switch may be arranged in four banks or rings, the segments of the respective rings being allocated respectively to dot signals on the first channel, dash signals on the first channel, dot signals on the second channel and dash signals on the second channel.

It is clear that either the brushes c and c or the segments n n n and m m m can be arranged to rotate but in the particular arrangement illustrated it is assumed that the brushes are rotated and moved from left to right as indicated by the arrow.

It will be noted that in the drawings the segment m is in contact with the charging brush 0 and soon a discharging brush comes into contact with that same segment. There is such a discharging brush 01 (2 respectively for the dot segments and the dash segments. These brushes, howevenare only used for discharging the signal charges belonging to the repeated transmission, and, to insure that the charges stored during the first transmission are not discharged through the brushes d and 11 it is arranged that when the segments which have received a current impulse on the first channel reach one of these discharge brushes d and d for the second channel, the conductors from the discharging brushes (1 and d are interrupted at the contacts I 0 and I3 operated by the cams I l and I4 which are driven at a speed of one revolution in the period of time taken by a brush to pass from the center of one contact such as n to the center of the next but one contact such as u Thus, the conductor 9 from the brush d is at the requisite instants interrupted at a contact In by a synchronously driven cam II. Similarly, the conductor l2 from the brush d is interrupted at the desired moments by a contact l3 opened by a synchronously driven cam I4. On the other hand, the impulses stored in the condensers through the charging brushes 0 and c and belonging to the first channel are kept stored in their condensers for almost a complete revolution of the distributor brushes until discharging brushes 9 and g for the dots and dashes of the first channel arrive on the segments belonging to the first channel. The conductor l5 from the discharging brush g of the first channel includes a contact I6 opened by a synchronously driven cam I! and in a similar way the conductor l8 from the dash discharging brush 9 on the first channel includes a contact I9 interrupted by a synchronously driven cam 20. Thus, if any impulses on the second channel remain stored in the condensers when the appropriate segments are in contact with the brushes 9 and 9 the contacts l6 and I9 are then opened and the second channel impulses are prev'ented'from discharging from those brushes. of the dots on the second transmission is represented by the circumferential distance between the brushes and (1 whereas the much longer time of storage of the dots on the first transmission isreprcsented by the circumferential dis- 1 tance between the charging brush 0 and the discharging brush g ','this being equal to the greater part of a revolution of the distributor switch. The difference between these two times of stor age is, of course, equal to the delay at the transmitter between the first and second transmission, so that the corresponding signals in a message on both transmissions are discharged simultaneously through the brushes (1 and g In asimilar way the periods of storage of the clashes on the second and first transmission are represented by the circumferential distance between charging brush (2 and the discharging brush d and between the brush c and the discharging brush 9 The difference between these periods is, of course, the same as for dots. t

Generally speaking, in a two channel system with'one' repetition, it is only necessary to store the signals of the first transmission to bring them into step at the receiver with the'second transmission, but in accordance with the present invention; it is necessary to storeboth transmissions, although the second need be only stored fora relatively short time as explained above. The reason is that both the first and second transmission impulses have to be subjected to the action of the automatic scrutinizing device which will be described below and which must have an opportunity to respond to distorted signals of the second transmission as well as of the first. It willflbe noticedincidentally that the instants at which the cams II, M, H and 2e open the contacts iii, it, Hi and i9 respectively are all the same, but owing. to the spacing of the distributor segments n n, n and m 172 m the first transmission is prevented from discharging through the conductors 9 and i2, while the second'transmission can and does discharge through those conductors but not through the conductors l and i8.

' There is a dot and dash relay allocated to each transmission. Thus 2| and 22 are the windings of the dot and dash relays respectively for the first transmission and '23 and 24 the windings of the dot and dash relay of the second or repeated transmission. It has already been explained that the signal impulses which correspond in the first and second transmissions affect the relay windings 2| or 22 and 23 or '24 at the same moments through the conductors i5, 25 or 18, 25 and 9, 2? or i2, 28.

Thus, when'a dot is received, it will, through the charging brush c charge two of. the dot condensers at times separated by a period of delay, but after impulses on the two channels have received their respective storage times they will pole'of the battery B; The opposite side'sof the Thus, the time of storage windings 2!; 22, 23, 24 are also connected direct to the negative pole of the battery B so that when a dash is received, as described above, the discharge of the respective storage condensers on the two channels through the discharging brushes 9 and :1 respectively will cause energization of the relay windings 2i and 23. Similarly, if a dash'is received without distortion, the

relay windings

22 and 24 are energized by the discharge of the dash'condensers through the brushes 9 and d respectively. In addition to the windings 2!, 22, 23 and 2d, the four relays are furnished with

locking windings

29, 30, 3I and 32 with

locking contacts

33, 34, 35 and 36 to' which these locking windings are directly connected. The windings 3 and 32 are connected through safety resistances r r and a contact 37! to the positive pole of the battery B, and similarly,'the opposite sides of the locking windings 29 and 36' are connected through safety resistances T3 and r and a contact 38 to the negative pole of the battery B. Consequently, when any one of the

relay windings

2t, 22, 23 or 24 is energized, the tongues 39, 4B, 4!, d2 of these relays remain held up until the locking circuit of the relay is interrupted by the cam 43 in the case of the first transmission and the cam 44 in the case of the second transmission. These cams 43, M are synchronously driven exactly as described with reference to Figures 3 and 4 of the drawings accompanying Patent No. 2,029,071. Thus, when a relay is momentarily energized by a condenser discharge, it is maintained energized for a substantially longer period by the current passing through the contacts 3'? or 38, but it is released by those contacts opening before it is to be energised by the following condenser discharge. Now the tongues 39 and of the dot relay 2| and dash relay 22 on the first transmission are connected together and are connected to the posi-. tive pole of the battery B. The main contacts t5 and it of these relays are each connected through a change over switch t! to the respective windings as, 49 of a centrally biassed differential relay, the tongue 50 of which is shown in the central position to which it returns. The other sides of the windings 48, 49 are respectively connected to the main contacts 5!, 52 of the dot and dash relays 23, 24 belonging to the second or repeated transmission. The tongues 4!, 42 of these relays are also connected together but in this case are connected to the opposite pole of the battery B, that is the negative pole.

In order to'aid in the further understanding of the invention, reference should be made to the diagram shown in Fig. 2 of the drawings. In this diagram the vertical lines t 15 t i represent the divisions between signal periods. The first heavyline extending across the diagram represents the position of the arm I, the upper portions M of this line indicating the position of the lever i in contactwith the marking contact M, while the sections S represent times when the lever l is in contact with the spacing contact S. In the period 73 t the arm is on contact M during the first half of the period and on contact S during the second half. In the period t t the arm remains on contact M, while in the period t t the arm remains on contact S. The next cross line represents by the sections 6 the periods in which the cam ii closes the circuit at i, while the next line represents by the sections 1 the periods in which the cam l closes the circuit at 5. The first line corresponds therefore to marking and the second to spacing. It will be evident that during the period t 1& the arm I is on contact S when cam 6 closes contact 4. Therefore no circuit will be closed, and this condition represents a space. In the period 15 i however the cam 6 closes the contact 4 during the second half period when arm I is on contact M, and thus charges the condensers h through brush c In the same way during the period 15 t cam I closes contact 5 during the first half period when arm I is on contact S, thus completing a circuit to brush and charging condensers k.

. The signals shown to the left of the line :rx in Fig. 2 are true or undistorted signals since each segment begins and ends exactly on the line between signaling periods. At the right of the line x-x the signals are represented as distorted, or in other words as terminating or starting before or after the division line between signaling periods. Along the line B the arrows indicate the change in position of the arm I, the downward arrows indicating a shift from M to S and the upper arrows a shift from S to M. It will be noted that with true signals these arrows fall at the end of some half period. To the right of the line :vx however, since these changes of position do not occur at the exact end of a signaling period, the arrows are out of line with the half periods.

The line C represents the action of the cam H 3. During the lower sections H6 of the line, arm I I is in contact with lever H6 and current can flow from condenser H2 through resistance M3 to the positive pole of the battery. On the other hand, the lines I I! represent the periods in which arm I I5 engages contact I I1, so that if any current flows during this period it must pass through the coil 63.

During normal operation with true signals, it is evident that the arrows B are always opposite the sections IIG of the curve C. Or in other words at the period of changing from M to S a circuit is always open through resistance H3 and not through coil 63. On the other hand, the arrows to the right of the line x-a: are at times opposite the sections III of the curve H6, as for example the arrows b 11 and 19 also indicated by arrows d (1 and d Th refore when the signals become distorted some of the changes in position of lever I will take place at such times as to cause current to flow through the coil 63 and operate the mechanism herein described.

The operation of the mechanism will be described in further detail herebelow.

If normally formed signals, that is signals without more than a certain degree of mutilation, are being received the operation is as follows: When a dot is received the relay windings 2| and 23 are energized as already described and these relays pull up and are locked for the period determined by the cams 43 and 44. The result of this is that there is a circuit from the positive pole of battery B through the conductor 53, through the tongue 39 of the dot relay on the first channel, contact 45, change over switch 4?, differential relay winding 48, contact 5| and tongue 5! of the dot relay on the second channel through conductors 54 and 8 to the negative pole of battery B. Thus, the dot winding 48 of the difierential relay is energized and the tongue 5|] drawn over against its dot contact 55. The result is that the positive of the battery B, which is connected through conductor 56 to the tongue 58 of the differential relay, is connected to conductors 57 and 58 of the main re-perforator MP and the spare re-perforator SP respectively, the

contact 59 of the change over switch 41 being closed. The mid-points of the windings of the perforators MP and SP are shown connected to the negative of the battery B in the usual way so that one half of the winding of each is energized to punch a dot in the paper strip.

If a dash is received, a similar circuit is completed, from the positive of the battery B, through the conductor 53, tongue 40 and contact 46 of the dash relay on the first transmission, through change over switch 41 and the dash winding 49 of the differential relay, contact 52 and tongue 42 of the dash relay on the second transmission and through conductors 54 and 8 to the negative pole of the battery B. The tongue 53 is therefore now drawn over to the right against its dash contact 50 so that the tongue 50 connects the positive of the battery B to the conductors BI and 62 respectively of the reperforators MP and SP, with the result that the opposite halves of their windings are energized and a dash is punched in the perforated strip.

When no signals are received, the tongue 50 of the differential relay remains in the central position illustrated. If, however, owing to a fault, the dot and dash relay windings 2|, 22, 23, 24 are all energized at the same time, then the differential relay is balanced and the tongue 50 remains in its central position so that no perforating takes place. It is, however, an advantage to leave blanks in the tape when a fault of this character occurs as it makes it possible for the operator to fill in the correct holes in the paper tape. Also in addition, undistorted signals which difier in the two receptions will also cause the occurrence of blanks and it may be arranged that upon the occurrence of either of these conditions, the operator may be notified by an audible or visual signal, although the circuits of such a signal are not shown in the drawings.

In order to deal with the reception of mutilated signals, in such a cased't is arranged that the mutilated signals on one transmission may be obliterated so as to leave the apparatus to be controlled by the signals of the other transmission. For this purpose an automatic scrutinizing device is employed arranged on the lines described in British patent specification No. 286,365. In that specification, if the signals are mutilated beyond a certain extent, the condenser K is arranged to discharge through an alarm device A shown in Figure 1 of the drawings accompanying that specification. In the present case, however, an electromagnet with its winding 53 is provided in the place of the alarm device A. Each time an additional tongue 96 of the receiving relay RR moves over, a condenser H2 is charged or discharged through a resistance H3 or through the winding 63. A cam I I4 is driven to make one revolution during the time of two aggregate centre holes, that is, two centre holes of the combined channel signals as received. Since the apparatus is organized to handle double-current cable-code signals, when the signals are undistorted, the tongue 95 moves over only at the beginning or half-way through each aggregate centre-hole period. The cam H4 is arranged and timed so that during these normal times of change-over of the tongue 96, the arm II5 rests against its contact II6, with the result that the condenser II2 then charges and discharges through the resistance II3. If, however, the tongue 96 of the receiving relay RR moves over during the times that cam 6 or cam I is closing its contact 4 or 5 respectivelyor closely before or after those times, since the lifts of the cam l l 4 are usually designed to provide some margin.- the cam I I4 has pressed the arm I I5 over against the contact I l1 and the condenser I I2 charges or discharges through the winding 63. The winding 63 may, however, be arranged under the control of a relay to be energized on the occurrence of signals of an amplitude in excess of a predetermined value, such as for example, might occur due to lightning or itmight be responsive both to excess amplitude and a predetermined degree of distortion. This device is arranged to Work in co-ordination with a pair of obliterating brusheso 0 with which the rotary distributor is provided. The winding 63 controls an armature 64 arranged when the winding 63 is energized to retract thecheck pawl 65 of a ratchet wheel. This ratchet wheel 66 is stepped round one tooth at each signal interval by a driving pawl 61 which is rocked by a synchronously driven cam 68 in step with the signals. On the spindle 69 of the ratchet wheel 66 there is a cam ill with a 66 and the cam l!) are turned by a spring I2 in the clockwise direction until the raised part II "of the cam ll] comes against a stop 13. When normal undistorted signals arrive, however, the winding 63 is not energized and consequently the ratchet wheel 66 is turned one step counter-clockwise at each signal interval until a point is reached when the raised portion ll of the cam comes into contact with a spring blade 14 and separates it from a contact 15 and at the same time acting through an insulating distance piece 16 it separates afurther spring blade 11 from a contact 18; that is the normal state of the apparatus when ordinary undistorted signals are being received.

The dot obliterating brush 0 is connected through a contact 19 controlled by a synchronously driven cam 80 to the contact 15 while the contact springs 14 and H are connected by'conductors 8! and 53 to the positive pole of battery B. Similarly, the dash obliterating brush 0 .is connected to a contact 82 also controlled by the cam 8|! and thence to the contact 18. The cam 80 as well as the other cams B, I, II, 14, ll, 20, 43, A l, .58 and H4 are all driven synchronously and held'in synchronism with the transmitting apparatus in thesame way as the receiver rotary distributing switch. All of these cams are oper-' I ated so as to make one revolution during each channel centre-hole period, that is, during every two centre-hole periods of the combined channel signals as received.

. Now if suddenly some mutilated signals arrive .and cause the winding 63 to be energized, the

latter retracts the check pawl 65 which may remain retracted by the action of .alocking wind- .ing 83, which will be referred to below, until the line receiving relay RR changes position. There-.

fore the spring 12 rotates the ratchet wheel 63 both-channels are all positively charged until the two pairs of spring contacts 14;, I5 and l1, 18 are .opened again. When theinutilatiqn ceases, the

pawl 61 again turns the ratchet wheel 66 step-bystep and it may be arranged that it has to turn through a distance of three teeth before the contacts l4, l5 and ll, 18 are separated so that the obliterating charges are cut off at a time of three signal intervals after the distorted signals cease.

The effect of the obliterating charges when the first transmitted signal inthe first channel is clear, and the second transmitted signal in the second channel is mutilated, may be briefly explained as follows: The obliterating charges belonging to the second channel will be discharged through the brushes d d after a short period of storage. result in the dot and dash relays 23 and 24 on the second channel being held up for the whole time during which the obliterating condensers are being discharged on the second channel. 'During that time, however, condensers are being dis-. charged at the discharge brushes g and g on the first channel, but these condensers are not charged with obliterating charges at all as owing to the long period of storage on the first channel, those condensers received the first transmission before the disturbance giving rise to distortion occurred, and. they received that part of the signal corresponding .to the part of the repeated transmission which was obliterated; therefore, they cause the dot and dash relays 2| and 22 belonging to the first channel to be. actuated in accordance with that part of the signal. It will be appreciated from the detailed circuits described above that the relays ,2] and-'22 then take full control be-' cause the circuits of the windings 48 and 49 of the difierential relay cannot be completed by the relays 23 and'24 a1one, but the circuits are only completed respectively when either the relay 2! or 22 is energized.

On the other hand, when the first signal is mutilated and the second signal is clear, the obliterating charges on the first channel are stored for a relatively long time and when they arrive at their discharging brushes g 9- the relays 2| and 22 on the first channel will be. continuously held attracted while the obliteratingcondensersare discharged .onthe first channel. However, owing to that long period of storage on'the first .chan; nel, the obliterating charges on the secondchannel have already been discharged and at the time in .question, under normal conditions,. signals without distortion are arriving at the discharge brushes d 01 on the second channel which were transmitted after the disturbance causing distortion had ceased, but which, nevertheless, owing to the time delay, corespond with the obliteratedfsignals on the first channel. In this .case, therefore, .the dot and dash relays 23, 2.4 on the second channel take charge entirely and control the energizing of either the dot or dash windings .48, 49 of the differential relay.

In order to ,deal with failures such as those due to fading, changing the line, or the insertion of ,a wrong plug, a further device is provided gen- .erally similar in construction to that just described. This device, which is generally of .the nature of a device for counting the reversals of the receiving relay RR, is only capable of deal.- ing with such faults if they have a relatively short duration. Generally, the receiving relay RR operates tongue 9.6 to energize relay Iill so that movement of the ratchet wheel 84, and the cam -81, controls the periods when obliterating charges are passed to the brushes oi and 0 The device has a ratchet Wheel .84 generally similar to the Wheel 66 and advanced one tooth at eachsignal When they are discharged they will period by a pawl 85' drivenlikethe pawl 91 from the cam 68. It also has a spring 86 tending to turn the ratchet wheel in a clockwise direction. The ratchet'wheel drives a cam 8'! with a raised portion 88 which is turned against a stop 89 when the check pawl 99 is drawn away from the wheel 84. There are twopairs of contacts in this case also under the control of the cam 81, also consisting in each case of a spring blade and contact 9|, 92 and 93, 94, but in this case, when the cam is in the zero position against the stop 99, these contacts are open as shown in the drawings so that then no obliterating impulses pass to the obliterating brushes 0 0?. As before the springs 9|, and 93 are connected .to the positive pole of the battery B for which purpose the conductor 95 is provided and the

contacts

92 and 94 are connected respectively to the obliterating brushes throughthe contacts 82 and I9.

To provide for the control of this device, the main receiving relay RR is provided with an additional tongue 96.and an additional pair of contacts 91, 98 controlledby the tongue and connected respectively to the positive and negative sides of the battery B through conductors 95 and 99. The tongue 96 is connected directly to a condenser I99, the other side of which is connected to a winding ml of an electromagnet which when energized withdraws the check pawl 99. The winding I9I is connected through a resistance I 92 to the positive pole of battery B. Thus, when the tongue 96 moves over to the contact 98, as shown in the drawings, there is a charging circuit for the condenser I99 through the winding I9I from the battery B and when subsequently the tongue 96 moves over to the spacing contact 91, the condenser I99 is able to discharge itself through the winding IM and resistance I92. Thus, every time the relay RR crosses over from its space to its mark contact or vice versa a current impulse passes through the winding I9I and each time the winding I9I retracts the check pawl 99 so at each cross-over of the relay RR, the ratchet wheel 84 is released and the cam 81 brought against the stop 89. If, however, the relay RR fails to cross over for a number of signal periods, the check pawl 99 is not withdrawn and the driving pawl 85 turns the ratchet wheel 84 step-bystep through the amount of one tooth at each signal period. After a predetermined number of periods which, in the example shown, is arranged to be twelve signal periods, the raised portion 98 of the cam 81 closes the contacts 9| and 92 and the

contacts

93 and 94 so that, as already described in connection with the automatic scrutinizing device, obliterating impulses are sent from the positive pole of the battery through conductors 95, I93 and the two pairs of contact springs and contacts 19 and 82 to both obliterating brushes and this continues until the receiving relay winding 83 is connected across the battery B through a pair of front contacts I94 controlled byits own armature 94 and through a pair of back contacts I95 controlled by the armature of the winding I9I. Thus, when the armature 65 is drawn down by thescrutinizing winding 63 the attain circuit through the winding 83 is completed to hold down the check pawl 65 until the relay RR reverses its position when the pawl 99 is drawn down and the contacts 595 opened.

The re-perforators MP and SP have their circuits controlled by switch blades 59 and I96 which connect the re-perforators as already described when they are closed at their upper contacts I91. They can be turned down, however, on to their lower contacts I99 when the switch 4'! is turned from its upper contacts I99 to its lower contacts;

II9. When both switches are in the uppenposition, the connections are as already described When they are in the lower position, however, the connections are altered in the following way: First of all the switch 41 connects the positive pole of battery B through the conductor 58 and the conductor III direct to the windings 48 and 49 of the differential relay so that this relay is only under the control of the relay tongues 4Ii and 42. The contacts 45 and 49 and the tongues: 39 and 49 are now removed from the circuits of the windings 48 and 49 by the switch 41. Secondly, the tongue 59 of the differential relay through its contacts and 69 can only connect with the windings of the re-perforator MP. The windings of the re-perforator SP on the other hand, are connected by the switch blades 59 and I95 though the contacts I99 to the contacts 45 and 4 9 of the relays 2| and 22 and thence through the tongues 39 and 49 to the positive pole of the battery B. Thus the signal received on the first transmission is perforated by the re-perforator SPand that received on the second transmission by the re-perforator MP.

It has already been indicated that the invention is applicable to codes other than the double current cable code. When the invention is, applied to ordinary cable code, for example, the relay 3 in the drawings is replaced by a relay, the tongue of which is biassed to the central position but is drawn over to the left or right respectively by incoming dot or dash signals. In that case, the cams 6 and "I instead of being arranged to operate the contacts 4 and 5 alternately as in the drawings, are set to operate the contacts simultaneously and are phased or timed so that the contacts 4 and 5 are closed at the middle of each period of contact of the relay tongue I due to the incoming dot and dash signals. In that case also the charging brushes c 0 are so placed that they are in contact with a segment during the time that the contacts 4 and 5 are closed. They would,.therefore, be staggered just as the other pairs of brushes are staggered in the drawings,

or in other words, in the position illustrated, the brush 0 would be making contact with the segment 11 Again for a receiver to operate on five-unit code, the relay I is as shown in the drawings so that its tongue will be in contact with the marking contact M or the spacing contact S during the time of each of the signal units which go to, make a character, this depending upon the combination of such mark and space units forming each character.. The cams 6 and I, in that case, are arranged to cause both contacts 4 and 5 to close at the middle of every such signal unit period and the brushes 0 c are placed so as to be each in contact with a segment during the times the contacts 4 and 5 are closed. That is to say, in the position shown, the brush 0 would be in contact with the segment n just as for ordinary cable code.

In the case of five-unit code, however, the relay 50 need not be a centrally biassed relay, butmay be a neutral relay drawn to one side or the other by the marking or spacing signals respectively and remaining in the position in which it is last placed until displaced by a further signal element. The re-perforators MP and SP are replaced by apparatus for transcribing the five-unit signals. Generally a five-unit synchronous system is operated as a multiplex system with the five-unit characters allocated in sequence to a number of channels. In such a system, the reperforators MP and SP would be replaced by synchronous apparatus for separating he channels and by the several printers allocated respectively to each channel; such synchronous apparatus and printers are, of course, well known in themselves.

It has already been indicated also that the invention is applicable to receivers with other forms of storage than the condenser storage illustrated in the drawings. When the invention is applied to a receiver employing mechanical storage, sets of movable members such as pins are employed for dots and dashes generally as set forth, for example, in British patent specification No. 111,343. These movable members may be arranged alternately on one drum, or at different axial positions on the drum. When the signals are repeated once so that the original transmission and the repeated transmission are'in efiect sent on two channels, alternate dot pins are allocated to the original transmission and to the delayed transmission and, similarly, alternate dash pins are allocated to the originaltransmission and to the delayed transmission. At one point in each revolution of the drum, all the pins are reset by a plough or similar cam device into the initial position and on arriving at the actuating point, if a dot signal is received one of the dot pins is displaced, and if a dash signal is received one of the dash pins is displaced. According to the present invention, during a period when the signals are distorted or mutilated beyond a predetermined degree, the whole of the dot pins and the whole ofthe dash pins are actuated and therefore set over into the signal position. Each set of pins, both the dot pins and dash pins, cooperate with a pair of levers which correspond to the dot discharge brushes d 9' and (1 g on the two channels respectively. Each pin which is actuated or set in the signal position acts upon both levers when it arrives at the appropriate positions and causes each lever to make a contact corresponding to those made by the discharge brushes in the drawings. The contacts are connected to conductors in which there are camclosed contacts such as shown in the drawings at l0, l3, I6, I9, the purpose being exactly the same as in the system illustrated, that is to say, to ensure that the circuits through the relay windings 2!, 22, 23 and 25 shall only be completed by the appropriate dot or dash pin s. In other respects, the system is similar to that illustrated in the drawings. 7

I claim:-

l. A telegraph receiving system for cable code signals, comprising in combination, a signal receiving relay for receiving an original and a repeated transmission of signals, a signal impulse storage device comprising a bank of condensers for storing the dot signals of both of said transmissions, a bank of condensers for storing the dash signals of both of said transmissions, synchronously actuated switching means connected to said receiving relay for charging said dot and dash storing condensers and synchronously actuated switching means for discharging said dot and dash storing condensers aiter'difierent time intervals for said two channels tobring the dot and dash signals of both channels into step, a receiving apparatus comprising separate elements connected res ectively to said switching means for discharging said dot storing condensers and to said switching means for discharging said dash storing condensers and means responsive to a predetermined degree of distortion in the received signals comprising synchronously actuated switching means connected to apply charging impulses to said dot and dash storing condensers" so as, to obliterate the signals of both of said transmissions received during the period of signal distortion.

2. A telegraph receiving system for cable code signals, comprising in combination, a signal receiving relay having spacing and marking contacts for receiving an original and a repeated transmission of signals, a bank of condensers for storing-the dot signals of both of said transmissions, a second bank of condensers for storing the dash signals of both of said transmissions, a local battery connected to the tongue of said signal receiving relay, synchronously actuated switching means for connecting the marking contact of said signal receiving relay to each of said first-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dot signal, further synchronously actuated switching means for connecting the spacing contact of said signal receiving relay to each of said second-mentioned bank of condensers in sequence so asto charge one or" said condensers from said battery upon the reception of each dash signal, synchronously actuated discharging means for discharging the condensers of said two banks after different periods. to bring the corresponding signals of both of said transmissions into step, a receiving apparatus comprising separate elements connected respectively to said switching means for discharging said dot storing condensers and to said switching means for discharging said dash storing condensers and means responsive to a predetermined degree of distortion in the received signals comprising synchronously actuated switching means connected to charge said dot and dash storing condensers so as to obliterate the signals of both of said transmissions received during the period of signal distortion.

3. A telegraph receiving system for cable code signals, comprising in combination, a signal receiving relay having spacing and marking contacts for receiving an original and a repeated transmission of signals, a bank of condensers for storingthe dot signals of both of said transmissions, a second bank of condensers for storing the dash signals of both of said transmissions, a local battery connected to the tongue of said signal receiving relay, synchronously actuated switching means for connecting the marking contact of said signal receiving relay to each of said firstmentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dot signal, further synchronously actuated switching means for connecting the spacing contact of said signal receiving relay to each of said second-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dash signal, synchronously actuated discharging means for discharging the condensers of said two banks after different periods to bring the corresponding signals of both of said transmissions into step, a receiving apparatus comprising separate elements connected respectively to said switching means for discharging said dot storing condensers and to said switching means for discharging said dash storing condensers, and means responsive to a pre determined degree of distortion in the received signals for passing from said battery to said banks of condensers, impulses of like polarity to the stored'signal impulses so as to obliterate the stored signals received during the period of signal distortion.

4. A telegraph receiving system for cable code signals, comprising in combination, a signal receiving relay having spacing and marking contacts for receiving an original and a repeated transmission of signals, a bank of condensers for storing the dot signals of both of said transmissions, a second bank of condensers for storing the dash signals of both of said transmissions, a local battery connected to the tongue of said signal receiving relay, synchronously actuated switching means for connecting the marking contact of said signal receiving relay to each of said first-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dot signal, further synchronously actuated switching means for connecting the spacing contact of said signal receiving relay to each of said second-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dash signal, synchronously actuated discharging means for discharging the condensers of said two banks after different time intervals to bring the corresponding signals of both of said transmissions into step, a receiving apparatus comprising separate elements connected respectively to said switching means for discharging said dot storing condensers and to said switching means for discharging said dash storing condensers, further synchronously actuated switching means organized to make connection with said condensers in sequence, connections from said last-mentioned switching means to said battery and contacts included in said connections and operable upon the occurrence of a predetermined degree of distortion in the received signals to connect said battery to said last-mentioned switching means.

5. A telegraph receiving system for cable code signals, comprising in combination, a signal receiving relay having spacing and marking contacts for receiving an original transmission and a repeated transmission of the same signals, a bank of condensers for storing the dot signals of both of said transmissions, a second bank of condensers for storing the dash signals of both of said transmissions, a local battery connected to the tongue of said signal receiving relay, synchronously actuated switching means for connecting the marking contact of said signal receiving relay to each of said first-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dot signal, further synchronously actuated switching means for connecting the spacing contact of said signal receiving relay to each of said second-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the re- 'ception of each dash signal, synchronously actuated discharging means for discharging the condensers of said two banks after different time intervals to bring the corresponding signals of both transmissions into step, a receiving apparatus comprising separate elements connected respectively to said switching means for discharging said dot storing condensers and to said switching means for discharging said dash storing condensers, further synchronously actuated switching means organized to make connection with said condensers in sequence, connections from said last-mentioned switching means to said battery, contacts included in said connections, a contact operating device driven in step-by-step fashion in synchronism with the received signals and operatively connected to separate said contacts after a definite number of signal periods and an electromagnet energized upon the occurrence of a predetermined degree of distortion in the received signals to declutch said mechanism so as to effect closure of said contacts.

6. A telegraph receiving system for cable code signals, comprising in combination, a signal receiving relay having spacing and marking contacts for receiving an original and a repeated transmission of signals, a bank of condensers for storing the dot signals of both of said transmissions, a second bank of condensers for storing the dash signals of both transmissions, a local battery connected to the tongue of said signal re ceiving relay, synchronously actuated switching means for connecting the marking contact of said signal receiving relay to each of said first-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dot signal, further synchronously actuated switching means for connecting the spacing contact of said signal receiving relay to each of said second-mentioned bank of condensers in sequence so as to charge one of said condensers from said battery upon the reception of each dash signal, synchronously actuated discharging means for discharging the condensers of said two banks after different periods to bring the corresponding signals of both channels into step, a receiving apparatus comprising separate elements connected respectively to said means for discharging said dot storing condensers and to said means for discharging said dash storing condensers, further synchronously actuated switching means organized to make connection with said condensers in sequence, connections from said last-mentioned switching means to said battery, contacts included in said connections, a contact closing device driven in step-by-step fashion in synchronism with the received signals and operatively connected to close said contacts after a definite number of signal periods and an electromagnet energized upon each change-over of said signal receiving relay to de'clutch said mechanism so as to cause said contacts to separate.

7. A telegraph receiving system for double current cable code signals of the type set forth, comprising in combination, a signal receiving relay for receiving a transmission of signals on one channel and a transmission of the same signals repeated after a predetermined time delay on another channel, a signal impulse storage device comprising a set of storage elementsfor storing the dot signals of both of said transmissions and a set of storage elements for storing the dash signals of both of said transmissions, synchronously actuated switching means for conveying impulses to the storage elements of said respective sets upon the arrival of dot or dash signals, a receiving apparatus connectedto said signal impulse storage device to be actuated simultaneously by corresponding signals of both of said transmissions and means responsive to a predetermined degree of distortion in the received signals for rendering said receiving apparatus insensitive to signals of both of said channels received during the period of signal distortion.

8, A telegraph receiving system for double current cable code signalsof the type set forth, comprising in combination, a signal receiving relay .for receiving an original transmission and a transmission of the samesignals repeated with a a signal impulse for storing the dot signals of both of said tran missions, a bank of condensers for storing the dash signals of both of said transmissions, synchronously actuated switching means for applying charging impulses to the condensers of said respective banks upon the arrival of dot or dash :signals and synchronously actuated switching apparatus comprising separate elements connect-ed respectively to said switching means for discharging said dot storing condensers and to,

said switching meansfor discharging said dash storing condensers and means responsive to a predetermined degree of distortion in the received signals comprising synchronously actu-' .ated switching means connected to apply charging impulses to said dot and dash storing condensers so as to obliterate the signals of both of said transmissions received during the period of signal distortion.

9. A telegraph receiving system for 'cablecode signals, comprising in combination, a signal receiving relay for receiving an original transmission a'nd a. transmission of'the same signals repeated with a predetermined time delay, a bank of condensers for storing the dot signals of both of said transmissions, a 1 second bank of condensers for storing the dash signals of both of said transmissions, synchronously actuated switching means connected to said receiving relay for charging said dot and dash storing condensers, synchronously actuated switching means for discharging said dot storing condensers and for discharging said dash storing condensers, said discharging means being so timed that stored signal impulses corresponding to the same signal elements in the original and repeated transmissions are discharged simultaneously, a receiving apparatus comprising a dot relay and a dash relay allocated to the original transmission with a dot relay and a dash relay allocated to the repeated transmission, connections between said relays and said discharging means for energizing the respective relays upon the discharge of corresponding stored signal impulses, connections for connecting in series the contacts of said two dot relays, connections for connecting in series the contacts of said two dash relays, a differential relay having opposed windings connected respec tively in circuit with the contacts of said two dot relays and in circuit with the contacts of said two dash relays, a pair of receiving instruments actuated under the control of the opposite contacts of said differential relay and means responsive to a predetermined degree of distortion in the received signals for causing certain of said condensers to be charged to prevent the selective operation of; said receivinginstruments due to the signals received during the period of signal distortion;

10. A telegraph receiving system for double current cable code signals, comprising in combination, a signal receiving relay for receiving an original transmission and atransmission of the same signals repeated with a predetermined time delay, a synchronously operated contact-making device connected to the marking contact and a second synchronously operated contact making device connected to the spacing contact of said receiving relay, a synchronously driven rotary distributor switch comprising a ring of contact segments allocated todot signalswa second'ring of contact segments allocated to dash signals, a dot charging brush co-operating with said first mentioned ring of contact segments and connected to said first-mentioned contact-making device, a charging brush co-operating with said second-mentioned ring of contact segmentsand connected to said second-mentioned contactmaking device, a bank of storage condensers respectively connected to the contact segments of said first-mentioned ring, a second bank of storage condensers respectively connected to the contact segments of said second-mentioned ring, a pair of dot discharging brushes co-operating with said first-mentioned ring 'of contact segments and a pair of dash discharging brushes co-operating with said second-mentioned ring of contact segments, connections from said discharging brushes and synchronously driven contact-making devices in said last-mentioned connections and timed so that the dot impulses derived from the original transmission are discharged through one of said dot discharging brushes and the dot impulses derived from the second transmission are discharged through the other of said dot dis charging brushes, while the dash impulses derived from the first transmission are discharged through one of said dash discharging brushes and the dash impulses derived from the second transmission are discharged through the; other of said dash discharging brushes, the discharging brushes being so spaced that stored signal impulses corresponding to the same signal elements in the original and repeated transmissions are discharged simultaneously, a receiving apparatus, comprising dot relays allocated respectively to the original and repeated transmissions, dash relays allocated respectively to the original and repeated transmissions, connections between said relays and said discharging brushes for energizing the respective relays upon the discharge of the corresponding stored signal impulses derived from the two transmissions, connections for connecting in series the contacts of said two dot relays, connections for connecting in series the contacts of said two dash relays, a differential relay having opposed windings connected respecsponsive to a predetermined degree of distortion in the received signals for connecting, during the period of signal distortion, said obliterating brushes to the pole of said battery which is connected to the tongue of said signal receiving relay.

11. A telegraph receiving system for receiving one transmission of signals and a single subsequentrepetition of the same signals, comprising in combination, a signal receiving relay, a signal impulse storage device operatively connected to said receiving relay and organized to store the signal impulses of the original transmission and the repetition in separate'storage elements and for different periods to bring the corresponding signals of the original transmission and of the repetition into step, means responsive to a predetermined-degree of distortion in either of the received signals and operative upon said signal storage device to destroy the identity of signal impulses stored therein and a receiving apparatus connected to receive simultaneously the stored signal impulses representing a signal of the original transmission and the same signal of the repetition and comprising a 'pair of relaydevices controlled respectively by the stored signal impulses of the original transmission and of the repetition and a receiving or recording circuit connected to be controlled solely by one of said relay devices at times only when the identity of the stored signal impulses controlling the other of said relay devices is destroyed.

12. A telegraph receiving system for receiving one transmission of signals and a single subsequent repetition of the same signals, comprising in combination, a signal receiving relay, a signal impulse storage device comprising two sets of storage elements operatively connected to said receiving relay and organized for one set to store the signal impulses of dot signals of the original transmission and the repetition and the other set to store the signal impulses of the dash signals of the original transmission and the repetition in separate storage elements and for different periods to bring the corresponding signals of the original transmission and 'of the repetition into step, means responsive to a pre-determined degree of distortion in the received signals and operative upon said signal storage device to destroy the identity of signal impulses stored therein by storing dot and dash impulses simultaneously in the respective storage units, and a receiving apparatus comprising a'pair of electromagnetic relays connected to receive simultaneously the stored signal impulses representing a dot signal of the original transmission and the same dot signal of the repetition, a further pair of electromagnetic relays connected to receive simultaneously the stored signal impulses representing a dash signal of the original transmission and the same dash signal of the repetition, a receiving or recording circuit for the dot signals including the contacts of said first pair of relays in series connection and a receiving or recording circuit for the dash signals including the contacts of said second pair of relays in series connection.

13. A telegraph receiving system for doublecurrent cable code signals including three kinds of signals consisting of only two current conditions persisting for difierent portions of a signal period, comprising in combination, a signal receiving relay responsive to the said two current conditions, synchronously-driven switching gear connected to the contacts of said relay and timed to pass forward current impulses from one or other contact of said relay upon the reception of a signal of two of the said three kinds of signals, a signal impulse storage device comprising a set of storage elements for storing the signals of one kind and a second set of storage elements for storing the signals of a second kind, means responsive to a pre-determined degree of distortion in the received signals and operative upon said signal storage device to destroy the identity of signal impulses stored therein and a receiving apparatus connected to receive simultaneously the stored signal impulses representing a signal of the original transmission and the same signal of the repetition and to be unaffected by stored signal impulses whose identity has been destroyed.

ALBERT HENRY MASSON.