US2361766A - Automatic telegraph apparatus - Google Patents

Description

Oct. 31, 1944. R HADEKEL 2,361,766

AUTOMATIC TELEGRAPH APPARATUS Filed June 26, 1942 5 Sheets-Sheet 1 Oct. 31, 1944.v R.' HADEKEL.

AUTOMATIC TELEGRAPH APPARATUS Filed June 26, 1942 5 Sheets-Sheet 2 R. HADEKEL Oct. 3l, 1944.

Filed June 26, 1942 5 Sheets-Sheet 3 ocr. 31, 1944.

R. HADEKEL 2,361,766

AUTOMATIC TELEGRAPH APPARATUS Filed June 26, 1942 5 Sheets-Sheet 4 Oct. 3l, 1944. R. HADEKEL AUTOMATIC TELEGRAPH APPARATUS Filed June vzes.V 1942 5 sheets-sheet 5 Patented Oct. 3l, 1944 UNITED STATES PATENT OFFICE Ruben naaekel, Gnppenhau, Warrington,

England Application June 26, 1942, Serial No. 448,642 In Great Britain April 1, 1941 12 Claims.

This invention relates to automatic telegraph apparatus. In such apparatus it is usual to employ for transmission a coding device operated for instance by a keyboard in which the letters or other symbols to be transmitted are converted into a code signal consisting of a series o1' electric impulses of diilerent duration or sign or amplitude, a transmitter operated by the code signals in successioxto send the corresponding impulses along the transmission channel and at the receiver a distributor separating the code impulses of each signal letter or other symbol and a. translator operated by each series of code impulses to indicate or print the letter or other symbol of the transmitted signal. In such apparatus it is the practice to employ mechanical and electro-mechanical devices for performing the various operations, both for transmission and reception, such devices consisting mainly of mechanically movable members operated by electromagnets. The object ofthe present invention is to reduce the number of mechanically movable parts and thus to enable a greater speed of transmission than in previous apparatus due to the limitations consequent upon inertia of mechanical parts, greater simplicity of the apparatus with ease of adjustment and convenient ampliiication of the signals at the receiving station.

According to the present invention there is provided an automatic telegraph apparatus wherein the coding, transmitting, distributing and translating devices, or any one or more of them, is or arev cnstituted at least in part bylone or more thermionic devices in which an electronic beam or space current is controlled to perform the required function in place of mechanical or electro-mechanical devices.

The invention comprises in automatic telegraph apparatus, transmitting apparatus comprising in combination a cathode ray tube having a series of code-anodes (or a long code-anode in combination with a series of deiiector plates) arranged so that the cathode ray may sweep along the code-anodes or anode, means for causing the cathode ray to execute such sweeping movement, a coding device-for determining which ofthe code-anodes (or deiiector plates) is eiective during a givensweeping movement and means responsive to current impulses to the cathode from the code-anode or anodes for transmitting signals to line. v

The coding device for determining which of the anodes or deflector plates is effective may Y translating device which is preferably of' therof thermionic valve which constitute coding and` mionic character `as hereinafter described.

The invention comprises also the various forms of cathode ray tubes which constitute transmitting and receiving devices and the various forms translating devices as hereinafter described.

Specic examples of constructions in accordance with the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a diagram in three sections upon sheets I, 2 and 3 of the drawings showing respectively, one form of coding and transmitting apparatus, a form of distributor for received signals to co-operate therewith and a thermionic translator for co-operation with the distributor, the whole comprising a complete system;

Figure 2 is a diagram of an alternative form of transmitting apparatus with a thermionic coding device;

Figure 3 is a diagram of an alternative forri of thermionic translator to take the place of the translator of Figure 1;

Figure 4 is a diagram of another alternative form of transmitter and receiver.

Referring to Figure 1, II represents diagrammatically, a cathode ray tube comprising a cathode I2, grid I3, main anodes Il, I5 and a series of target code-anodes I6 to 20 inclusive. There is also a `target starting anode 2| and deflector plates 22, 23 which, if suitably charged with aI regularly increasing potential, will cause the cathode ray to scan the whole series of anodes, beginning with the starting anode 2| and terminating at the furthermost code-anode I6. It is not necessary to describe the construction of a. cathode ray tube of this kind in detail as with the knowledge at present available, given the characteristics which are set out in this specification, it is perfectly possible for a competent person to assign the appropriate dimensions and location to the various parts. l

A series of keys 24 is provided, corresponding in number to the number of symbols which are to be transmitted. Each of these keys hasa contact, or contacts, 26 on the movable part comprise means selectively to connect certain which closes against a, corresponding contact 2l beneath it when the key is depressed. The contacts 26 on the movable portions of the keys are al1 connected together to the grid I3 of the cathode ray tube by line 228. It will be noted that the ilxed contacts 21 are arranged in iive columns under one another in the drawings. The numbers of the contacts 26 which are carried by each key, and their location, are arranged in accordance with the code which is decided upon so as to close against one or more of the columns of the contacts 21, all the contacts 21 in any given column being connected together. The columns of contacts 21 are connected to five code wires 28 to 32 inclusive, which are connected respectively to the code-anodes I6 to 28 inclusive. Thus, pressing any particular key will energise one or more of the code-anodes and each key renders eiectve a different selection of the anodes in accordance with the` code. The keys may be operated either manuallyor by any desired mechanism, of which various forms are known. Moreover, all the keys are disposed upon a rocking bar which carries a contact 33 insulated from the rocking bar, connected to positive and adapted to play between two contacts 34, 35 so that when the keys are raised the contact 34 is closed and when any key is depressed the contact 35 is closed. `The keys, with the rocking bar and their contacts, constitute'the coding device.

The cathode I2 of the cathode ray tube II is connected to negative line 36 through a resistance 31 and, whenever the cathode ray impinges upon a, live target code-anode surface, (i. e. are connected to grid) the'current passing is altered and causes a change of potential in the resistance 31. The resultant uctuations of potential of the cathode I2 are connected to an amplifying circuit 38, the details of which it is not necessary to describe, and thence to the transmission line 39. The operations are regulated by auxiliary apparatus comprising the thermionic valve 48 and thyratron valve 4I. The grid 42 of the valve 48 starting anode 2|, ready for the next signal.

after the starting signal a set oi' code impulses will be forwarded in strict accordance with the code contacts of the signalling key which has been depressed.

As soon as the key which has been depressed is released the contact 35 is broken and the contact 34 closed. 'I'his connects the line 53 to the positive of the supply and through the resistance 64 the positive potential reaches the grid 55 of the thyratron valve 4|. As a consequence the thyratron valve strikes and discharges the condenser 58, thereby returning the cathode ray to its initial position where it impinges upon the As will .be obvious the time interval required for all these operations is extremely minute so that signals may follow one another without regard to any limitations which would be imposed if the various alterations of the circuit connections depended upon the usual electro-magnetic relay armatures and the like.- Consequently the capacity of the system to transmit signals depends solely upon the speed with which the keys 24 can be operated and as these can be made very light,

is connected by a resistance 43 to the negative line and normally serves to bias the valve so that no current passes from the anode 44 to the cathode 45. When however, one of the keys 24 is depressed the contacts 33, 35 are closed connecting the line 46 to the positive of the supply and this, through the resistance 41, is connected to the grid 42 thus reversing its polarity. At the same moment the starting anode 2| of the cathode ray tube I is rendered effective through the line 48 to grid I3 and astarting signal is despatched to the transmission line 39. The coding device is so arranged that the contacts 33, 35 do not close until after the coding contacts 26, 21 have closed and rendered eiective the appropriate anodes of the series I6 to 28.

As soon as the grid 42 is reversed in polarity the valve 48 passes a current through the resistance 49 to condenser 58 and commences to charge the condenser, the potential of which rises. The positive terminal of the condenser is connected by a line 5I to the deilector plate 22 of the cathode ray tube and the opposite deiiector plate 23 is connected through a resistance 52 to a potentiometer system 252. It will be appreciated that up to this time the cathode ray has been held deflected on to the anode 2|, but as the condenser 58 charges up, the cathode ray begins to scan the anodes I6 to 28, one after the other. Whenever it reaches an anode which has been rendered effective by the closing of one of the contacts on the coding key which is depressed, a current impulse passes and is transmitted by the amplifier 38 to the transmission line 39. Thus,

and if desired operated by power through an appropriately punched paper strip, or otherwise in known manner, the capacity may be made extremely high.

Coming to sheet 2 of Figure 1 of the drawings, this shows the receiving end of the transmission line 39 which delivers the received signals (which may be transmitted wireless signals) tc an ampliiler 68. The amplifier 68 is connected to a distributor cathode ray tube 6I, the construction and operation oi' which is now to be described.

The distributor 6I comprises a cathode 62, main anode 64 and vertical scanning defl'ector plates 65, 66. 'I'he anodes are arranged in a double series, 61, 68 being the flrstpair and the others being numbered, in pairs, seriatim up to 15, 16.

There is a terminating anode 11. Although in the diagram the pairs of anodes are shown concentric with one another in order that they may be separately seen, it is to be understood that they are in fact arranged in two series side by side at the same radius from the cathode. The cathode ray would normally strike the anodes of one series in the course of its scanning movement under the influence of the deflector plates, 65, 66, but it can be deflected onto the other series of anodes by means of two horizontal deflector plates 18, 19. The incoming impulses from the amplifier are delivered to the plate 18 by the connection and the plate 19 is connected by the connection u 8| to a control part of the apparatus hereinafter described. The incoming impulses from the amplier 68 are also led by a line 82 to the grid 83 of a thyratron valve 84 which will be described as the starting thyratron. The first impulse which comes in over the line 39 will therefore serve to "trigger the valve 84 and it will be recollected that this flrst impulse is a starting impulse eected by the closing of the contacts 33, 35, and is separate from the code signal which immediately follows. The effect is to connect the line 85 (in the diagram), which is attached to the anode 86 'of the thyratron valve 84, to negative line 81 through the valve 88, the anode 89 of which is coupled to the cathode 90 of the thyratron valve. There is a condenser 9| which is connected through resistances 92, 93 to the positive line 94 and this condenser, as soon as the starting impulse is received, begins to charge, building up the potential of the line 95 which is connected to the vertical deector plate 65 of the cathode ray tube 6|. 'The cathode 62 is itself connected to the negative line bythe connection 96 joined to 85, and as a result the cathode ray from the cathode 62 is deflected and begins to scan the anodes of the tube 8|, beginning at the bottom pair 61, 68 and moving twoards the terminating anode 11. The capacity of the condenser 9| and the value of the resistances' 92. 93 through which it is fed, are so regulated that the rate of charging will correspond with the rate of scanning of the anodes I6 to 20 by the cathode ray of the transmitter tube Therefore, the cathode ray in scanning the anodes 61 to 16 will be in synchronism with the impulses which are coming in through the amplifier 60. In the absence of an impulse it will impinge on the` series of anodes represented by the odd numbers 61 to 15, but whenever an impulse is received it will be deilected by the connection of the plate 18, 19 on to the even series of anodes 68 to 16. At the termination of its scanning movement, the cathode ray impinges on the anode 11. Current passes through the anode 11, goes to the primary 91 of a transformer, the secondary 98 of which is connected by a line 99 to the grid of a thyratron Valve which is connected by a line |0| to the cathodes of the translator valve arrangement which is shown on Figure 3 of the drawings, and which is hereinafter described. The cathode 300 of this valve |00 is connected by line 30| to resistance 93. This ensures that the translator valve operates a translated signal as soon as the cathode ray in' the tube 6| has completed its scanning movement. l

The anodes 61 to 16 are connected to the corresponding series of transformers |01 to ||6, inclusive, and the secondary of each transformer is connected to a grid of a thyratron valve. 'I'hese thyratron valves are numbered in the drawings ||1 to |26, inclusive. The anodes of the valves ||1 to |26 are connected to the positive line 94 and the cathodes are connected through resistances |29 to the line |26, which is at the negative end of the resistance 93 in use for charging the condenser 9|. It will be appreciated that before the code impulse comes in to the line 39 the cath odes of the valves4 ||1 to |26 will be passing no current and will be connected to the negative line through resistance l| 30 and the connections 65,

|32, |33 and |28. They will therefore beat negative potential with respect to line 30|, but as soon as the thyratron valves are caused to strike by impulses transmitted to their grids |34 from the anodes of the tube 6|,'they become positive with respect to line 30|. Connections |31 to |46 inclusive, are provided from the cathodes of the thyratron valves to the translator valve now to be described and the effect is that of these connections only those are rendered positive which correspond to the code impulse received.

The connections |31 to |46 inclusive, are carried to a translator circuit which is shown on the third part of Figure l of the drawings (sheet 3).

Here these connections appear as the circular connections, which are correspondingly numbered. Disposed in a circle around the connections there are a number of heptode valves |50, corresponding in number to the number of the keys 24 of the transmitting apparatus. Each of these valves has five grids, an anode and a cathode, the cathodes being connected to the line |0 from the thyratron valve |00, and the anodes to positive line through resistance It is obvious that these valves can pass current only if all the five grids of any one valve are positive and the grids are connected up to the lines |31 to |46 in the manner indicated in the drawings in such a way that with any Jgiven signal the whole of the five grids of only one valve of the series can be rendered positive simultaneously. VWith a different signal the five grids of another valve will be rendered positive and with still another signal yet another valve, and so on throughout the series. Thus, whatever the signal transmitted, one valve of the translator valve series will be ableto pass current. which will affect the resistances I6| which are in series with each valve and by appropriate connections, which are not shown in the drawings and which may be made to known printing or perforating apparatus, will cause the appropriate symbol which has been transmitted to be automatically printed, perforated, or otherwise indicated, at the receiving station.

To summarise the operation of the receiving apparatus, when an impulse is received through line 39 this will be amplified in the amplifying apparatus 'and will first strike the thyratron valve 84, putting the condenser 9| in circuit and leading to the building up of potential in the line 95. 'Ihis will cause the cathode ray in the cathode ray tube 6| to scan the anodes 61 to 16. Voltages are so adjustedthat for a `potential diierence of the plates 18 to 19, which corresponds to a spacing part of the signal received through the line 39, that is to say a part corresponding to that part of the signal where one or more of the anodes I6 to 20 are not energised, the cathode ray beam will impinge upon one of the odd numbered anodes 61 to 15, while for a part of the signal impulse which corresponds to a live anode of the series I6 to 29, the plates 18, 19 will bear a potential difference sufficient to deflect the cathode ray on to one of the even series of the anodes 68 to 16. .The ten lines |31 to |46 will therefore be selectively energised accordingly. y

In the translator device the line |31 is connected to all the innermost grids of one-half of the valves |50 and the line |38 to the innermost grids of the other half of the valves.

Therefore, a spacing impulse which immediately follows the starting impulse can only energise a valve in the lower half of the diagram. whereas a marking impulse which immediately follows the starting 60 impulse from the transmitter can only energise valves in the upper -half of the diagram. A glance at the transmitter key connections 24 will show that all the uppermost keys give a marking impulse immediately after starting and the low- 66 ermost keys of the series all give a spacing impulse.

Similarly with the lines |39 and |40; these are connected to the second grids of the valves in such a way as to sub-divide the lowermost group into two sets, one set connected to the line |39 and the other to the line |40. 'I'hey are also connected to the uppermost half of the valves in such a way as to divide the grids thereof into two sets, one connected to the line |39 and one to the line |40, and a spacing impulse which follows in the second position of the signal can only energise the second grids ofone-half of the valves. Similarly with the lines |4| and |42. these are connected to the third grids of the valves and sub-divide each of the four sets thus far created into two more. The lines |43 and |44 effect a further sub-classification on the Thus any given signal, with its spacing :ind marking impulses, is automatically caused to operate one valve only, which precisely corresponds to the signal, and as soon as the cathode ray of the tube 6| has finished scanning the anodes 61 to 16, it will impinge upon the final anode 11, .discharge the thyration valve |00, and thus cause the particular one of the valves |50, which has been energised in all its five grids by the signal, to pass a current from the line to positive line and print or otherwise give an indication of the signal which has been transmitted. y

The rate of building up of the condenser 9| which has produced the scanning eiort of the plates 65, 66 is such that immediately after the cathode ray has impinged upon the anode 11 l the voltage will be suilicent to re a thyratron valve |52 which is in parallel with the condenser 9|, so as to discharge the condenser and thereby bring the cathode ray in the tube 6| back to normal. At the same time this will produce a current surge in the primary |53 of transformer |54, and the secondary |55 of this transformer will, through the line |3|, apply a negative cutoff voltage to the grid of the valve 88, thereby momentarily interrupting the current through the thyratron valve 84 and extinguishing the passa-ge of current therethrough. This re-sets all the valves instantaneously ready for the next signal.

Figure 2 shows diagrammatically an alternative coding arrangement from that of Figure 1. In Figure 1 each of the keys 24 makes a number of contacts which serve to render eifectivey directly, appropriate anode plates in the cathode ray tube Inl Figure 2 each key |60 makes one contact only, |6|; and for coding purposes a thermionic coding valve |62 is providedy which has a cathode |63 and a considerable number of grids 64 which are located in a circle about the cathode. One of each of the contacts |6| is connected by lines, not shown in the drawing, directly to one of the grids |64 so that when any key is depressed one of the grids becomes positive and any anode which is in line with the grid which has been thus rendered positive, will be energised. Five anodes are provided which are numbered in the drawings |65 to |69 inclusive. Although these are shown in the drawings as concentric circles, it will be appreciated that they must be grouped about thev grids |64 in such a way that each of them is exposed directly to the cathode electron emission, the natural arrangement for which is that the five anodes should each be formed as a cylindrical surface and put together end to end, the grids |64 occupying a cylindrical surface inside them and the cathode |63 being constituted by a wire or small cylinder inside the grids, but the valve is laid out as shown in the diagram, in order that all the parts may be more easily seen.

It will be noted that each 'of the anodes |65 to |69 is drawn shaded over certain sections of its extends from the positive supply of the apparatus. The lines |10 to |14 are also connected to a cathode ray tube 18|. Each of the lines is connected to one of ve pairs of horizontal deector plates, the second plate of each pair being f connected to a suitable positive potential; the deflector plates are arranged in a series |82 to |86 inclusive, in such a way as to deflect the beam opposite flve target anodes |81 to |9| respectively. The target anodes |.81 to |9| are connected by -a line |92 to grid I3. There is a starting anode 2| which corresponds to the anode 2| of Figure 1 and is also connected to grid I3. A contact 35 closed by contact 33 whenever any one of the keys |60 is depressed is connected to line 46 which corresponds to line 46 of Fig. 1. On the other hand when the key`is raised the contact 33 engages a contact 34 on line 53 which also corresponds toline 53 of Fig. 1. v

` Deilector plates 22, 23 are provided similarly to the correspondingly numbered plates of Figure 1 and, again similarly, there is a cathode l2, grid |3 and main anodes 4, l5; also an amplifying circuit 38 connected to outgoing line 39. The other parts of the circuit exactly correspond to Figure 1 of the drawings and do not need further description.

In operation, when any key |60 is depressed, it renders positive the particular grid |64 to which it is connected in the valve |62. As a consequence the anode or anodes of the series |65 to |69 which are in line with the grid so rendered active are able to pass current and therefore the potential of the defiector plate or plates of the series |82 to |86 whichA are directly connected to these anodes, will be modified.

As in the case of the apparatus of Figure 1 the cathode ray in the cathode ray tube |8| commences to scan the end of the tube beginning with the anode plate 2| as soon as any one of the keys |60 is depressed and a starting impulse is sent to line. The cathode ray is arranged to be directed so as to be just oi impingement on the anodes |81 to |9| but when it passes any one of the deilector plates |82 to |86 which has been energised by the coding valve |62, the cathode ray is deflected on to the corresponding anode of the series |81 to |9| and a current impulse will pass which is amplified by thel apparatus 38 and transmitted to'line 39. The remainder of the operation is as described in relation to Figure 1.

Figure 3 shows a decoding valve or translator to take the place of the series of heptode valves |50 of the third sheet of Figure 1. The principle of this valve is exactly similar to that of the valves |50 but all the parts are within a single envelope. There is a cathode 200, a series of ve concentric grid structures 20| to 205 inclusive, and a set of anodes 206 outside all the grids. The number of the anodes 206 is equal to the number of the different symbols which are to be decoded and they are connected to a series of resistances 5|, corresponding to the resistances |5| of sheet 3 of the drawings. The grids 20| to 205 are subdivided, the innermost one 20 into two parts, the

. next 202 into four parts, the next into eight parts and then into sixteen and the outermost into thirty-two parts, one grid to each anode in the last case. These series of grids are coupled to the lines |31 to |46 in a way which precisely corresponds with the coupling of the five grids of the heptode valves |50. In order to avoid complicating the gure, the connections|31 to |46,

which would show as concentric circles between the grids, have not been drawn in Figure 3, but it will be obvious how these connections are made to the little alternate lateral projections 201, 208 which are shown projecting from the grids. In this valve, at the expense of making a single very big valve, some of the complication of connections of Figure 1 is obviated. The operation is exactly as already described.

Figure 4 shows an alternative circuit in which the coding, and decoding arrangements are somewhat diiferent, although the principle of the employment of cathode ray apparatus in place of mechanical coding and decoding devices is retained. A number of keys 2||I are provided corresponding to thel number of symbols to be transmitted, which are connected by lines 2|I directly to anodes 2I2 in a cathode ray tube 2 I3. In addition there is a starting anode 2|4 connected to grid I3. An insulated contact which has been numbered in the drawing 35, as it corresponds closely with the contact 35 of Figure 1, is closed by a movable contact 33 whenever any one of the keys 2|IJ is depressed. There are deflector plates 22, 23 to cause the cathode ray, from the cathode I2, to scan the anodes 2 I2, beginning at the anode 2 I4, and the effect is that as soon as a key is depressed a starting signal is sent to line and at a time interval later, which time interval depends upon the key depressed, there is a second signal sent to line. The duration of this time interval determines the signicance of the signal. As far as possible the rest of the parts of Figure 4 are numbered correspondingly to Figure l, and the operation may be regarded as being in other respects similar so far as the transmitting end is concerned.

Coming to the receiving end, the line 39 delivers signals to an amplifying apparatus 60 and the general means for initiating the scanning operations of a receiving cathode ray tube 26| by means of thyratron valves 84 and |52 and condenser 9|, are the same, the corresponding parts being similarly numbered. However, in place of the pairs of anodes 61 to 16 there are a series of anodes in the valve 26| which are numbered 262 in the diagram. Each of these anodes is connected to one of a series of transformers 263 by a line 264, and the secondaries 265 of the transformers are connected by lines 266 to the grids 261 of thyratron valves 268. Only the iirst two of the series of valves 268, and their corresponding transformers, are shown in the drawings, the rest being merely duplicates. The result is that when a signal is received from the line 39 the cathode ray is caused to commence to scan the anodes 262, but at the commencement of its movement it is arranged to be projected in such a direction as just to miss the anodes. It will be noted that the cathode ray will be moving over the anodes 262 in precise synchronism with the ray in the tube 2| 3 which is moving over the anodes 2I2 of the transmitter, and thus synchronism is re-eiected for every symbol which is transmitted. As soon as the cathode ray of the tube 2I3 impinges upon an anode which has been rendered live by the depression of the corresponding key 2|0 at the transmission station, it willl send an impulse to line 39 and this impulse will energise the deiiector plates 16, 19 of the receiving tube 26|, thereby deecting the cathode ray on to the corresponding anode of the tube and firing the corresponding thyratron valve 268. This serves to operate appropriate means for printing, punching or otherwise indicating the symbol which has been thus .i transmitted; Itis not necessary to describe again in detail the remainder of the connections, which are similar to Figure 1.

Although the invention has beendescribed With reference to certain speciiic embodiments, it will be understood that many variations could be made within the scope of the invention, one outstanding advantage of which is that it practically eliminates, for those parts of the apparatus which employ cathode ray tubes and valves, time lag in response, thereby speeding up the transmission. Moreover the automatic synchronisation which is effected and the speed of the actual transmissionv in code of any signal, render the transmission largely proof against erroneous signals being transmitted and proof against ready decoding by unauthorised sources.

1. In a telegraph system the combination of a transmitter comprising a cathode-ray tube having a series of code-anodes, a cathode, and, means 'to move the electronic cathode-beam to cause it to sweep over the code-anodes seriatim, a coding device to render any desired selection of the codeanodes eiective and means, responsive to current impulse to the cathode from the effective codeanodes to transmit a signal by a. set of impulses in accordance with the selected code-anodes as the electronic beam sweeps thereover, a receiver comprising a, cathode-ray tube having a series of signal-indicating anodes, a cathode, and means to move the electronic cathode-beam to cause it to sweep over the signal-indicating anodes seriatim, means at both transmitter and receiver to set in action each of said electronic beams simultaneously by an initial current impulse at the beginning of each signal so as to cause said beams to perform their sweeping movement and thereafter to return to a, .predetermined initial position to await the next signal, whereby separate synchronizing means is rendered unnecessary, and means associated with the receiver to indicate to an operator the signal so received.

2. A telegraph system as claimed in claim 1 wherein the means comprised in the transmitter l to render any desired selection of the codeanodes effective include a set of keys each having a selection of contacts connected to some of the code-anodes so that each key completes circuits 1go a selection of the code-anodes peculiar to the 3. A telegraph system as claimed in claim 1 wherein the cathode-ray tube of the transmitter comprises a series of code-anodes each connected to an individual key so that the differences between signals depend upon the time interval which is required for the cathode-beam to reach a particular code-anode which has been rendered live by depression of the key corresponding to the signal in question.

4. A telegraph system as claimed in claim 1 wherein the means associated with the receiver to indicateito an operator the received signal comprise a decoding valve device in the form of a plurality of heptode valves.

5. In automatic telegraph apparatus, transmitting apparatus comprising in combination a cathode-ray tube having a long code-anode,

means to cause the cathode-beam to sweep a path in the same direction as that of the code-anode, a series of deflector plates disposed adjacent to said path, a coding device for selectively energizing deflector plates of the series so that when the cathode-beam 'sweeps said path the energized deiiector plates deflect it, whereby for part only of its path it strikes the code-anode, and

means responsive to current impulses from the code-anode to the cathode for transmitting sig-Y nals to line.

' 6. Transmitting apparatus as claimed in claim wherein thecoding device comprises means selectively to connect certain defiector plates to positive in accordance with the code.

7. Apparatus as claimed in claim 5, wherein the coding device comprises a series of keys corresponding in number to the symbols vwhich it is desired to code and .eachkey is adapted to close a plurality of circuits corresponding to the deflector plates which are to be energized.

8. Apparatus as claimed in claim 1 wherein the coding device comprises thermionic valvemeans, having a. cathode-beam emitting-means. a series of grids each arranged opposite a different area of the beam-emitting means and corresponding grid-by-grid to the symbols which it is desired to code, and a plurality of coding-anodes corresponding to the deector plates, said coding anodes being disposed in sections codewise, that is to say so that opposite to each of the grids there is located a section of the coding-anodes corresponding to the deector plates which it is desired should be rendered eiective.

9. Apparatus as claimed in claim 1 wherein the cathode-ray tube of the transmitter'comprises one anode for each signal to be transmitted, in combination with a starting anode, so that the code signal is constituted by a starting im- 10. In automatic telegraph apparatus, receiving apparatus. comprising in combination a cathode-ray tube having a series of signal-indicating anodes arranged so that the cathode-beam may sweep along the signal-indicating anodes, means responsive to an initial signal for each code group transmitted for initiating sweeping movement of the cathode-beam and for returning it thereafter to initial position, deflector plates energized by code signals received for deilecting the cathode-beam laterally to its path on to particular indicating anodes of the series during its sweeping movement, and means responsive to current impulses from the indicating anodes for indicating the anodes thus impinged upon by the cathode-beam.

1l. Receiving apparatus as claimed in claim 10 wherein the means for indicating which anodes pulse. and a second impulse the import of which v is determined by the time interval between the two impulses. Y

lthrough the thyratron valves to a thermionic decoding device which comprises a plurality of symbol anodes shielded from the cathode-beam by grids and the grids are so connected to the thyratron valves that only one symbol-anode is rende d active for any given combination of code signal impulses received.

RUBEN HADEKEL.

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