US2279353A

US2279353A - Telegraph system

Info

Publication number: US2279353A
Application number: US231479A
Authority: US
Inventors: Hendrik C A Van Duuren
Original assignee: Nederlanden Staat
Current assignee: Nederlanden Staat
Priority date: 1937-09-25
Filing date: 1938-09-24
Publication date: 1942-04-14
Anticipated expiration: 1959-04-14
Also published as: FR851674A; GB519633A; NL50112C

Description

April 1942- H. c. A. VAN DU'UREN TELEGRAPH SYSTEM .Filed sept. 24, 1938 4 Sheets-Sheet 1 Ala/14 April 14, 1942. Q VAN RE 2,279,353

TELEGRAPH SYSTEM Filed Sept. 24, 1938 4 Sheets-Sheet 2 Wa ez/WW) Patented Apr. 14, 1942 TELEGRAPH SYSTEM Hendrik C. A. van Duuren, Wassenaar, Netherlands, assignor to Kingdom of the Netherlands, Post Ofi'ice Administration, The Hague, Netherlands Application September 24, 1938, Serial No. 231,479 In the Netherlands September 25, 1937 30 Claims.

The present invention relates to telegraph system's, particularly of the type-printing class. The invention is primarily concerned with the troubles arising in these systems from transmission disturbances. Transmission disturbances are particularly present in radio transmission, where static and fading frequently mutilate the signals. For this reason, the invention has its primary field of utility in connection with radio transmission, but it will be understood that the invention can also be employed in wire transmission systems over land and cable lines for avoiding difilculties arising from atmospheric disturbances, induction from adjacent power lines, etc.

British Patent No. 419,526, issued to Arjen Bakker and myself, illustrates one type of telegraph system which has been developed to cope with the problem of atmospheric disturbances in radio transmission. The system of this patent operates upon the theory of utilizing two carrier waves of different frequencies in each oneway path of communication. One signal element, which may be termed the marking element, is imposed on one carrier wave, and the other signal element, which may be termed the spacing element, is imposed on the other carrier wave.- The theory underlying this mode of operation is that so long as both signal elements on the two Waves arrive undisturbed at the receiving station, the latter will continue its printing operation, but if one of the signal elements is mutilated by a parasitic impulse or by fading, the receiver will be stopped automatically and means put into operation for obtaining the emission of a non-mutilated signal from the transmitting station. This prior type of system requires the use of four transmission channels, two for the signal elements of the message and two for the corrective or controlling signal elements which are adapted to be transmitted back from the receiving station to the transmitting station.

The present invention, on the other hand, only requires two transmission channels for the same purposes. In other words, the present invention provides a system in which the mutually protected elements are emitted one after the other on a single channel. The signal elements are made mutually protective by having them comprise impulses having different electrical values which are so chosen as to produce a constant ratio or constant total electrical value for each transmitted signal. this constant relationship in the signals received at the receiving station is an indication that the Any deviation from signal has been mutilated, calling for a retransmission of that signal. For example, if the signals emitted on the single wave are thought to consist, in the manner of Baudot code, of a given number of'negative and positive signal elem'ents, which are transmitted in a combination characteristic of each signal, then the protection of the signal is obtained according to the invention by causing the proportion of positive and negative elements to be identical in each signal. The occurrence of a parasitic impulse or of fading during the transmission of the signal is detected through the deviation from normal of the proportion of positive and negative elements as determined at the receiver.

If it were attempted to employ the normal five unit code, represented by the Baudot code, in the application of the above idea, a shortage of-difierent combinations would result, because when operating upon the basis of a given proportion or ratio of positive and negative elements there would be several combinations of such five unit code which obviously could not satisfy the requirements relating to this proportion or ratio. It is therefore desirable to employ a code in which the signals are made up of a greater number than five units or elements.

In the preferred embodimentof my invention herein disclosed I employ a code containing eight units or elements. The eight unit code is particularly suitable for the practice of the present invention in that when the code is obtained by conversion from the five unit code which is usually employed in mechanical telegraphs or land lines, thirty'of the thirty-two combinations. of the five unit code may be changed into eight unit code signals by simply adding three elements, of which three, two, one, or none are marking units. Only those signals of the five unit code which have five identical units have to be transformed in a diiferent manner.. 1

In the system of the aforementioned British patent, each signal element is protected in and of itself, and hence it is possible to transmit a single element as warning of the reception of a mutilated signal. In the system of the present invention each signal element is not protected in and of itself, but, to the contrary, the protection only applies to every combination of elements constituting a signal. Hence, in this system an entire signal is employed for this purpose. .Inasmuch as the eight unit .code, when j cted to the conditionthat each s na shall a greater number of signals thanthe first me'ntioned number. Inasmuch asseveral-warning signals are available in the above described code relation, it will be evident that consecutive warning signals, each time suitably'amended'or differentiated from preceding warning signals, may repeatedly be given.

The preferred embodiment of the invention as it will .be hereinafter described utilizes" a' transmitter which'transmits with an eight" unit code, in response to' received signalswhich, are formed on the'basis of 'a five unit'code. The transmitter includes transforming apparatus for transforming the five unit signalsinto eight unit signals. Similarly, this embodiment utilizes a-receiver which receives the eight unit code, and whichreceiver includes transforming apparatus which retransfor ms the received eight unit signals into five unit signals for controllingv a printer. It will be clear that this transforming apparatus is not essential to the application of the fundamentals of my invention. For example, in situations where messages originate directly at the transmitting station, or in situations where messages received ovei'a land-wire'in a five unit code (such as the-Baudot code) are printed at the transmitting stationand are then manually recast into a code having a different number of units, there is no necessity of employing such transforming apparatus. However in view of the fact that in most instances the large bulk of messages will be conveyed over land lines to the radio transmittingstation, and in view of the fact that these land lines are usually equipped to work with a five unit code, it is desirable to provide the aforesaid transforming apparatus to transform the five unit code into the eight unit code at the transmitting station, and to transform the eight unit code backintothe five unit code at the'receiving station. In this regard, it is to be understood that the clescrlptionof an eight unit system is not to' be interpreted as' a limitationof the invention, since seven units suffice for obtaining the required nuniber'of combinations; provided that in each signal four and three equal signal elements should always occur, in which case seven'units provide 1.23:4;56- 7 my r Poo COIIlblIlatlOflS However, the use of eight units is more advantageous sinceit appears to simplify the apparatus'v considerably, as in'fthis case all signals from the five unit-code, except those having five equal elements, may be used in the eight unit code by merely completing these signals to eight unit signals through the additionof three elements. i

If a disturbanceis signaled at the receiver due to thearrival of an incorrect proportion of positive and negative elements in a signal, a warning has to be given to the transmitter in the manner indicated above; A transmitter in the direction AB will thus have't'o transmit the five unit signals ready at A (e. g., perforated in a paper strip) after their transformation into eight unit signals, and moreover warning signals to transmitter B, as required by reason of disturbances on the path BA (i. e., whenever warning signals which have been transmitted back from transmitter B along the path BA have been mutilated in transmission). The receiver B has to transform the eight unit signals arriving on the radio path into five unit signals, which transformation consists in the simple admission of the first five of the elements of'the signal as received to a five unit printer, except in the cases in which theoriginal signal contains five equal elements, or where it was a. signal for indicating a disturbance on the path BA (i. e., where transmitter B has been required to transmit a waming signal back along the path BA, which warning signalis mutilated in transit, thereby calling for the transmission 'of a warning signal in the reverse direction from transmiter A along the path A3 to receiver B). The'particular require-- me'nts'to be satisfiedby-the transmitter A and receiver B will-be better understood by'referring to-the accompanying drawings illustrating one preferred embodiment of my invention; In these drawings:

Figure-l is a circuit diagram of the transmitter apparatus of each station;

Figure 2 is a circuit diagram of the receiver apparatus of each station;

Figure 3 is a chart'illustrating different combinations available in the eight unit code;

Figure 4 is atiming diagram of one group of contactors employed in the transmitter;

Figure 5 is a timing diagram of one group'of contactors employedin the receiver; and of the start-stop teletype connected thereto, and

Figure 6 is a timing diagram of different contactors employed in the transmitter and in the receiver, grouped according to the shafts by which these contactors are operated.

Referring first to Figure 3 which shows difierent code combinations in which the eight unit plishing this relation, fourcode combinations of the eight possible combinations of the three added elements are required; 'viz., for the cases in which one, two, three, of four positive elements were present in the original signal. These four combinations have been shown in Figure 3 at the lines I-IV. In this chart, the signal elements denoted by the circles or zeros may, for convenience of reference, be referred was the spacing elements, and the signal elements denoted by the X marks may be referred to as the marking elements. For example, in the Baudot code the flat tops in the current wave are commonly referred to as marking elements'and the valleys are commonly referred to as spacing elements. Correspondingly, in the present disclosure the X marks in Figure 3 may be regarded as the tops or marking elements and the circles as the valleys or spacing elements, this arbitrary designation, however, being solely for convenience of a, reference. Referring more particularly to these so called norma signals indicated in lines I-IV, line I illustrates the three signal elements which are added when the original five unit signal contains only one marking element; line II the three signal elements which are added when the original signal contains two marking elements; line III the three signal elements which are added when the original signal contains three marking elements; and line IV the three signal elements which are added when the original signal contains four marking elements.

A further requirement of the transmitter is that if the original five unit signal has five equal elements, such signal must be transformed into a balanced eight unit signal comprising equal numbers of positive and negative elements. There are two instances of such a five unit signal, one in which all five elements are positive (spacing elements and the other in which all five elements are negative (marking lements X). These two signals are shown in their transformed state in lines 0 and V in Figure 3, from which it will be seen that these two transformed signals differ from each other, although the sequence or grouping of the last three elements is the same in both instances. This sequence or order of the last three elements differs, however, from each of the other four sequences or groupings I, II, III, and IV. When the receiver receives either of the two signals 0 or V it perceives that a transformation has taken place. Because the sequence of the last three elements is the same in both 0 and V they only exhaust one of the three-element combinations, which, together with the normal signal combinations I, II, III, and IV, exhaust five combinations in all.

Hence, of the eight possible three-element combinations, three yet remain, and these are used at the transmitter for the emission of warning signals under control of signaling relays, these signals being shown respectively in lines VI, VII. and VIII in Figure 3. The receiver thus has the particular requirement to select between (1) normal signals, represented at I-IV in Figure 3; (2) transformed signals indicated at O and V in which the first five elements have to undergo a retransformation opposed to the transformation experienced by these elements at the transmitter; and (3) warning signals indicated at VI-VII in Figure 3. Lastly, the receiver B should be adapted to control its own transmitter B for the emission of warning signals to A whenever a disturbance occurs on the path AB. Similarly, in this same regard, the reception of a warning signal at B has to occasion the repetition of the warning signal previously mutilated on the path BA. The converse of this situation is, of course, true in the event'that the message signals are transmitted at B for reception at A.

Referring now to Figure I, the transmitter comprises the five contact fingers or feeling tongues 2| to 25, inclusive, adapted to coact with the perforated paper tape in which the message is recorded in conventional five unit code.- When these contact fingers are in their upper positions (which is the case when the tongue registers with perforations) they establish engagement with cooperating upper contacts, and when they are in their lower positions they establish engagement with cooperating lower contacts. Difierent polarities or potentials are imposed on these contacts to establish the marking or spacing elements of the first five-unit portion of the complete eight unit signal. The perforated paper tape is intermittently advanced under control of the timing contact 2, which has connection with negative battery and which governs the energization of the conventional starting magnet S; The otherterminal of this starting magnet has connection through ground with battery mid-point. Throughout the circuit diagrams of Figures 1 and 2, all ground connections will be considered transmitting apparatus RT also includes as a part of its equipment a suitable radio receiver RR, which will be described later in connection with Figure 2. It will be noted that the first three contact fingers 2|, 22 and 23 of the tape controlled contact fingers have permanent electrical connection with the first three distributor segments 33, 34, and 35, and that the last two

contact fingers

24 and 25 of said group are operable to have connection with the next two distributor segments 36 and 3'! through relay armatures 64 and 65, the latter performing controlling or coding functions which will be later described.

The apparatus for adding the three extra signal elements to make up the eight unit code comprises a bank of three supplementing

relays

29, 3B, and 3|, it being noted that their

respective armatures

26, 21, and 28 are connected with the last three segments 38, 39, and 40 of the transmitting distributor TD. These relays are of the polarized type in which each armature remains in its actuated position after the cessation of the actuating current impulse and until a current impulse of opposite polarity traverses the relay winding for actuating the armature to the other-position, these armatures remaining in rest positions (in engagement with their left hand contacts) when negative polarity is applied to the relay windings. When the armatures are in engagement with their left hand contacts they receive positive polarity and when they are in engagement with their right hand contacts they receive negative polarity. The windings of said relays 29, 30, and 3| are connected with the timing

contacts

8, 9, and I0, respectively, and also with the timing

contacts

5, 6, and 1, respectively. The timing contacts to 2D, inclusive, are all mounted on a common shaft V for synchronous operation, these contacts only being shown diagrammatically in Figure 1 but actually having the varied timing intervals illustrated inFigure 4. The shaft V has the same speed as the rotary member of the transmitting distributor TD. A second shaft V associated with both the transmitter and receiver of each station operates the timing contacts a, b, c, d, e1, ez, and es of the transmitter, and also the timing contact I of the receiver (see Figure 6). This second shaft V is adapted to be started by the electromagnet ST of the receiver (Figure 2), as will be later described, and rotates at a speed which is 6; of the speed of the first mentioned shaft V Three other shafts V V and V are also arranged to rotate timing contacts of the transmitter under the control of electromagnets associated with the receiver. Shaft V rotates timing contacts A1, B1, and C1, and ,isadapted ceiver; shaft V. rotates the timingcontactsAz;

Br, and C2 of the transmitter, and is adapted to be started by the electromagnet S of the. re-' pair of polarized relays 4| and 42 which. are

adapted to be energized whenever. all of the contact fingers or-feeling tongues 2|-25, inclusive, occupy similar positions. The movement'iof'all of said contact fingers 2|25. to similar positions causes these fingers to have potentials of equal polarity. If, then,.shortly. after. the fixation of the five unit signal'the bank of. timing contacts l4zto l8, inclusive, are closed, it will be evident that a current of corresponding direction will fiow through the polarized relays 4| and 42. This current will be of. one: polarity if all of the contact fingers2'l-25 are in their raised positions, and will be of the opposite polarityyif allof said contactfingersare in their lowered positions. Accordingly, this current will energize the relays 4| and 42 and'cause either'one or. the other ofthe armatures 45 or 45 to moveto circuit closing position, depending upon the polarity of the current to said relays. At the moment at which timing contacts |4-|8 are closed; the

timing contacts

3 and 4 are open (see Figure 4), so thatthe spacing and marking contacts associated with the contact fingers 2l-25 are connected to the-voltage source through resistances 43 and 44. It will thus be seen that the closure of timing contacts |4-|8 does not result in a complete short circuit in the event'that the contact fingers 2l-25 do'notall occupysimilar positions. In such case, the transforming apparatus should not function, and to this end the relays 4| and 42 do not carry current at this time, inasmuch as the contacts M to [8, as well as contact l3, then have the potential of battery mid-point. When therelays 4| and 42 are .energized they close holding or lock-up circuits through their armature contacts 45 and 46, such holding circuits being opened upon the opening of timing contact l3. Therefore it will'be seen that until the opening oftiming contact I3 the point 41 has a potential corresponding ,inpolarity to that of the similarly positioned contact fingers 2| to 25.. This voltage, whether of one polarity or the other, now energizes the relay48, which attracts its armatures 49,. 50, 5| and 52. The nature of the transformation resulting from this energization of therelay 48 will be first described in the situation where a five-space signal is being applied to the contact fingers 2| to 25, in which situation the contact fingers are all on their lower. contacts Figure ,1,.such corresponding to five successive circles according to the-system of notation shown in Figure 3. After the armatures 49 and 50' have been attracted by the energization of the relay winding 48, contact finger '2l remains connected with positive '(such being the spacing current or zeros 2,279,353. to. be started by the electromagnet S3 of the -re'-' to. negative through the: new position of 'armature '50; contact'finger'23 remains connected-to positive; contact finger. 24 is now-connected. to negative through .thenew position' of. armature 50; and contact finger25 remains connected to positive. Thus, the first five elements 'of signal 0 of Figure 3 are formed. With reference to the last three elementsof this signal formed through the supplementing relays 29, 30, and 3|, these three relays are energized at this'time through timing contacts 5, 6', and 1. Thus, relay is connected with negative: through timing contact 6 and armatures 69 and H; and relays: 29 and 3| are connected-withpositive through-timing contacts .5 and 1 and armatures 5| and HI. Such energization of the

relays

29, 30, and 3| results in the

relay armatures

26 and 28 having negative or marking voltage and the relay armature 21'having'positive orspacing voltage, thus producing the last threesignal elements shown in signal 0. The-converse situation of transforming a fivemarking unit signal (wherein all five contact fingers 2 I are in their upper positions corresponding to five marking elements denoted X in Figure 3) into the eight unit signal V of Figure 3 will be apparent from the description of the preceding transformation. In this latter transformation, the energized position of the armature 49 reverses the polarities supplied to the upper contacts associated with contact fingers 2|, 23, and 24 in much the same manner that the armature 50 reversed the polarities of the lower contacts of contact fingers 22 and 24 in the preceding transformation.

It should be observed that when relay 48 is energized, its armature 52 interrupts the test conductor 32 so that this conductor and the relay 53 are rendered inactive.

Referring now to the manner in which the normal signals (I-IV'of Figure 3) are formed, the three control relays 4|, 42, and 48 remain at rest whenever a signal having four or less equalelements is applied to the contact fingers M45. The three

signal supplementing relays

29, 30; and 3| return to rest position in engagement with their positive contacts when negative is applied to the relay windings over the circuits closed by the timing

contacts

5, 6, and 1. Under such conditions, these latter relays thus add spaces.(the

of Figure3); contact finger 22 is'now' connected signal impulses represented by the circles in Figure 3) to the five units of the original signal. In this manner, a signal having four marking units and one spacing unit is converted into the eight unit signal IV of Figure 3. In the case of a signal in which the number of marking unitsissmaller than four, the polarized relay 53 is energized in a bridge connecting with the resistances 54-6| by way of the test conductor 32. This test conductor will'not carry current when the eight unit signal is balanced, because such causes equal amounts of positive and negative currents to flow in the resistances 54-6l. In order to effectthe conversion of the different normal signals, the five unit signal is tested three times by the action of timing

contacts

8, 9, and I9, which coact with timing contacts it and I2. If the signal-is not balanced on the first testthe first supplementing relay 29 is brought into the marking position (armature to the right) over a control circuit through contact 62 of relay 53 and through timing contact 8. If at the, second test the signal is not yet balanced, thesecond supplementing relay 30 is brought into' marking position. Finally, if the signal should not yet be" balanced atthethird test, the third supple- 8, 9, H), II and I2, it will be seen from Figure 4 that the contact ll intermittently establishesa holding circuit for the relay 53, which holding circuit is closed concurrently with each closing of contact I2 and which carries over through each closed circuit interval of the successively operating

contacts

8, 9, and I0.

Referring now to the manner inwhich the warning signals (VI-VIII of Figure 3) are formed, it will be seen that the signals to V, inclusive, utilize all groupings or sequences of the three added elements except those shown in these last three signals VI, VII, and VIII. These last three are used for Warning purposes, but it is necessary that they be completed by five preceding elements of such polarity that a balanced eight unit signal results. Three relays S S and S operating in conjunction with blank relay BL, serve to give these warning signals. An understanding of these functions will be facilitated by first consideringthe operation of said blank relay BL. The energization of this relay is under the control of timing contacts a, B1, B2, B3, l9, and 26. Responding to the energization of said relay are armatures 63, 64, 65, 66, and 61. The actuation of armature 63 causes relay 48 to be energized, and this establishes the correct polarity.

of the first three elements and of the last three elements of the eight unit signal corresponding to signal 0 of Figure 3, such operation occurring independently of the position of the contact fingers 2l-25. This will be apparent from the preceding description of the operation of relay 48, from which it will be recalled that the first three elements of the transformed eight unit signal were the same whether the contact fingers were in their upper positions or in their lower positions, as evidenced by signals 0 and V of Figure 3. With regard to the last three elements of the signal, the three supplementing relays 29, 36, and 3l'pr'oduce marking, spacing and marking elements respectively (signal 0) in the same manner that they produced this three element combination in the transforming operation previously described. With regard to the fourth and fifth elements, these are given their correct polarity by the armatures 64 and 65 of relay BL. Relay armature 66 establishes a holding or lookup circuit for the winding of blank relay BL during the time that timing contact I9 is closed. The signal produced by the above operation is therefore a so-called blank, i. e., the receiving printer is supplied with a five space signal, to which signal it does not respond at all. That is to say, the signal which is transmitted over the radio path is signal 0 (Figure 3) but after transformation at the receiving station into a five unit signal it takes the form of five spaces, to which the receiving printer does not respond. The armature 61 of relay BL at the transmitter interrupts the circuit of the starting relay or winding S, as otherwise, when a blank is given, a letter would be missed. It should be further observed that this blank signal is also given in the absence of a perforated strip in the transmitter, i. e., the signal then given is signal 0 of Figure 3. Inasmuch as this signal consists of successive reversals of spacing and marking elements it considerably facilitates the receiver adjustment.

As distinguished from blank, the system uses, in known manner, thesignal letterblank consisting of five markings (therefore signal V. of Figure 3) and which is used to change from numbers to letters. On the radio path-this signal is in the eight unit form indicated at V, but after transformation at the receiving station into a five unit signal it takes the form of five markings.

Referring again to the function of the signaling relays which cause the emission of warning signals, the first warning signal is given by the simultaneous energization of relays BL and S The energization of relay BL operates its armatures 63 to 61, inclusive, as above described, and

'to the distributor segments 36 and 3'! respectively. As a result, warning signal VI of Figure 3 is emitted from the transmitter. At the receiver, this will indicate that the transmitter on itsside has transmitted a signal which has been mutilated before reception, for which reason it has to be repeated. The manner in which the receiver influences its own transmitter will be hereinafter described. Meanwhile, it should be noted that after the transmission of the first warning signal from A to B, A transmits a second warning signal, this time by the simultaneous energization of relays BL and S". Armatures ill and -H are thereby'actuated, which transmits negative polarity to supplementing relay 29, positive polarity to supplementing relay 30, and negative polarity to supplementing relay 3|. Armature I2 is also actuated, which transmits negative polarity to the distributor segment 31- for producing a marking element as the fifth signal element. Such actuation of the armatures of relays BL and S results in the emission of signal VII of Figure 3. This second warning signal from A now causes at receiver and transmitter B the repetition of as many signals as have been transmitted during the time between the emission of warning signals VI and VIII, as will be hereinafter described. After the transmission of the second warning signal, a third Warning sig nal is emitted by A, such being effected by the simultaneous energization of relays BL and S The energization of the relay S causes actuation of the arinatures13 and M. The actuation of' armature 13, together with the actuation of the armatures which respond to relay BL, results in.

quence, warning signal VIII is thereby emittedv The arrival of this signal from the transmitter. at the receiver B results in the emission of as many signals from its transmitter as has been emitted between the sending of warning signals VII and VIII.

Referring now to the circuit diagram of the receiver, illustrated inFigure 2, .it will benoted that this apparatus comprises a multiplicity of timing contacts 9| to :I I8, inclusive, all mounted on'ashaftv 'Said shaft ;V :has the-samespeed as the rotary :member of; the receiving distributor RD, andlthe timed relationofrthese several contacts isillustrated in Figure5. The receiving apparatusqalsobincludes the'timing contact I which is mounted on the shaft V associated with the transmitting apparatus, as previously described. The I receiving apparatus, comprises the polarized"receivingirelay I6 which receives the'signals from any suitable radio receiver RR, such radio apparatus being well known, and hence not being shown indetail. As previously described, each station having such radio receiving-apparatus RR also includes as apart of its equipment a suitable radio transmitting apparatus RT, illustrated in Figure 1; The receiving relay I6 energizes the receiving distributor RD with difierent polarities corresponding to the positions consecutively occupied by the armature of the polarized sending relay I5. The receiving distributor RD is shown with sixteen contact segments, the first thirteenof which: connect with the windings ofthe polarized relays :"I'I to 89, inclusive. The fourteenth, fifteenth, and sixteenth segments are connected back to the windings, of

relays

82,83, andz84. The first eight relays TI to 84, :inclusive, are energized in conformity with a received eight unit signal. The last'five relays 85 to, inclusiveytogether with the last three relays, 82, 83, and-rfl4 ofthe first group of eight, serve for thereception of the next eight unit signal. The relays 111-89 are of the polarized type in which; after the cessation of current flow through the relay windings, the armatures remain in the positions last assumed. Thirty of the utilized thirty-five combinations of the eight unit code (excludingsignals O, V, VI,

VII, and VIII of Figure 3) are received in the following manner. Upon the arrival of one of these thirty combinations, the first five elements of the first-mentioned signaliare received by the relays TI to 8|, and are directed to thelprin'ter without any modification. This is effected at suitable moments throughtiming contacts 94 to 98, and occurs for all signals except those in ofthe nextsignal have arrived tocontrol relays 85-89, Thearmatures of said latter relays are connected to the printer at suitable moments through-timing contacts 99-483.

Relays II4-andII5 are energized on the arrival of a signal corresponding to O or on the arrival of a signal corresponding to V (Figure 3). Timing contacts I04 and I85 havesuch timed sequence as to cause the aforementioned signal which first arrives to energize relay H4, and to cause the aforementionedsignal which next arrives to energize'relay II 5, this distinction applying in case of arrival of signal 0 as well as of signal V. The energization of relay II4, for exwhich the three element combination received on the last three relays 82, '83, and,84iof the first group corresponds to the'last threeelements of signals 0, V, VI, VII, and VIII; When the signal terminateswith the last three elements of the latter combinations, thearmatures of

relays

82, 83, and 84, and consequently thearmatures II6-I2I of relays III, vII2, andzII3, are caused to occupy such positions that one 'of the relays I I4, H5, S S or S is energized via circuit'connections established through armatures IIB-I2I,

'Relays H4 and, I I5 are energized by signals 0 and V. The energization of relay I I4actuates armatures H4, I22, and I23;-; and the energize,-

tion of relay II5 actuates armatures 5'; I24,-

ample, causes its armatures I22 and I 23 to be brought intoengagement'with their right hand contacts, whereby the upper and lower contacts of the first four relays II-80 have the same polarity impressed thereon as is impressed on tion'being established through conductor I23. That is-to say, the fifth element of signal 0 or the, fifthelement of-signal V will determinethe polarities or voltagesimpressed on these upper and lower contacts of said first four relays. In consequence, thefirst five elements of the signal undergo a retransformation (as will appear from Figure 3) opposite to the" transformation that they received in the transmitter. In corresponding manner, the other relay II5 takes care of the signal which is' next received by imposing on the upper and lower contacts of relays'85-88 the same polarity as isimposed on the, armature of relay 89, such connection being established through conductor I25. Relays S S and S are'energized when the transmitter of, the other station emits warning signals VI, VII, and :VIII (Figure 3), such-energization being through circuit connections established by way of relay armaturesIIB-IZI in consequenceof the three element combinationsat the ends of these warning signals, whichelements are received by the

relays

82, 83, and 84.

The apparatus at the receiver for the detection of gmutilations in the signals operates as follows: .The said signal which arrives first energizes relays 11-84; the armatures of these relays are then connected in circuit with relay ST by way of timing

contacts

92 and 93 through the resistors I2B-I33. The upper and lower contacts gized. This'is because four of the relays II-89 have transmitted OIIBlDOIaIitY of current flow through timing contacts 592, 93to therelay ST, and tfonrzother relays-onthissame, group fill- 89 have transmitted the opposite polarity of current flow through said

timing contacts

92, 93 to said relay ST. Hence, the two polarities balance each other out andthere is no energization of relay ST. In any other instance, i. e., whenever the signal is a mutilated one, relay ST is momentarily energized because an unbalanced conditionexists either by reason of a greater number of positive elements than negative elements or a greater number of negative elements than positive elements. This closes a circuit through armature I40 which energizes relay 3T The latter relay actuates armatures Ml, I42, and. I43, the first of which completes a holding circuit for said relay through timing contact H0. The actuation of armature M2 interrupts a circuit connection to battery mid-point which in turn prevents energization of relays S S and S whenever the reception has been mutilated. The actuation of armature I43 interrupts the printer start circuit so that the mutilated letter is not printed at receiver B. The energization of the relay ST starts the shaft V for transmitting warning signals from transmitter B, in a manner which will now be described.

The shaft V started by the relay ST of receiver B, rotates at A of the speed of the transmitter shaft V and said shaft V controls timing contacts a-d, e e and e of the transmitter B, and also controls timing contact I of the receiver B, which remains open during thirty-six revolutions of the transmitter shaft V so that the starting of the printer is prevented during this period of time required for transmitting the Warning signals VI-VIII from the transmitter B, added to the time required, in the most unfavorable case, for station A to react to these signals.

This most unfavorable case would occur when warning signals VI and VII have not been received without mutilation, and only warning signal VIII has caused the transmitter A to be set back. In station B, the closing of timing contacts a and b (Figure 1) causes the energization of relays BL and S whereby warning signal VI is transmitted. Six revolutions later timing contacts a and c are closed, thus energizing relays BL and S causing warning signal VII to be transmitted. On the sixth revolution of said shaft after signal VII has been transmitted, contacts a and d are closed for energizing relays BL and S to cause the emission of warning signal VIII.

Timing contacts e1, es, and es of station B exercise a necessary control function when, during the described operation of the shaft V of station B, the transmitter A transmits warning signals to the receiver B for the purpose of indicating to that station that its warning signals transmitted over the path BA have been mutilated. In this situation the warning signals transmitted back from station A cause timing contacts A1, B1, and C1, or A2, B2 and C2, or A3, B3, and C3 of transmitter B to become operative. The nature of the above mentioned control function exercised by the timing contacts e1, e2 and es of station B will be best understood after first considering the action of warning signals VI-VIII on station A, which will now be described.

Warning signals VI-VIII, transmitted from B, will arrive at A after the transmitting shaft V of A has rotated one or more revolutions beyond the revolution which emitted the message signal which was mutilated in its transit from A to B. The telegraph transmitter of station A should therefore be set back by several signals; in the particular embodiment herein disclosed it is set back by five signals under normal operating conditions. However, if the transmitter A has meanwhile been engaged in transmitting a warning signal to the receiver'B, this number should be made smaller by one; because during the emission of said warning signal the perforated strip has not been advanced. For the purpose of interrupting the transmitter start circuit (station A), the armature 61 of relay BL isinterposed in series between the timing contact 2 and the winding of the transmitter start device S. When warning signal VI arrives at receiver A it causes relay S to be energized, thereby causing shaft V to be started. This shaft likewise turns at a speed of of the transmitter shaft V and rotates timing contacts A1, B1, and C1. Timing contact A1 energizes the back step relay T of the transmitter (station A) for six revolutions of the transmitter shaft V Timing contact B1 energizes relay BL for twenty-nine revolutions of the transmitter shaft V so that transmitter A transmits the aforementioned blanks during thattime. Attention is called to the fact that the telegraph transmitter (station A) will only start when relay S is energized, as well as when stepping backwardly when relay T is energized. The start circuit of relay S, which was interrupted at armature 61 during the emission of blanks, will therefore have to be closed again during the six back steps, such closure of this circuit being effected at timing contact C1, which establishes a shunt around armature 61. It should be noted at this point that the closure of contact 01, in order to be effective, also requires the closure of contact :21, which will be referred to later. The emission of blanks (from station A) during the twentythree subsequent steps is necessary because at the sender B the received mutilated signal has resulted in further operations, such as the emission of signals VII and VIII, and during which time station B should not accept signals. The possibility that station A Will not react before signal VIII arrives should also be taken into consideration; in this case the inactive period is required for enabling the transmitter to return to the correct letter.

Start relays S S and S are so mechanically interlocked that when station A has reacted to signal VI, the signals VII and VIII emitted by station B will not be effective to again initiate a starting operation at station A.

As thetelegraph transmitter was set back by six steps, whereas the transmission delay only required it to be set back five steps, the receiver B must not print the first signal to arrive after resumption of the transmissionfrom station A. To prevent the printing of this first signal, timing contact I remains open for one turn longer.

In the above mentioned instance where the telegraph transmitter should be set back one step less, i. e., in the event that there has been a reaction to signal VI, this function is performed by rotary contact e1 which is connected in series with rotary contact C1, and to which reference has already been made.

In the event that station A does not react to signal VI, it is almost a certainty that it will react to one or the other of the two succeeding signals VII and VIII. The operation of the apparatus under the control of the latter signals corresponds to that under the control of signal VI, timing contacts A2, B2, and C2 being set into operation by signal VII, and timing contacts A3, B3, and C3 being set into operation by signal VIII, in the same manner that timing contacts A1, B1, and

C1 were set into operation by signal VI. The delays and the number of back steps1;will,.of. course, differ in the case of each-of these three signals. as will be apparent fromFigure 6. ,If station A should not react to a single one of these three warning signals, receiver B will miss some letters.

The possibility .of such an occurrence is, however, exceedingly small on normal circuits. In any case, the system prevents .the printing of mutilated letters, and the missing .of a great numberof letters cannot pass unnoticed.

The .synchronism of the transmitter shaft V atstation Aandreceiver. shaft V at station B, as well as that of transmittershaft V at station B and receiver shaft V of. station A,.is maintained in known manner. I

In the foregoing description I have described a sequence of operations wherein the message signals are transmitted from station A for reception at station B, but it will be understood that the message signals can, of course, originate at stationB for reception at station A, in which case this samesequence of operations. occursin reversed relation with respect to the two stations.

While I have illustrated and describedwhat I regard to bethe preferred embodiment of my invention, nevertheless it will be understood that such is merely exemplary and that numerous modifications and rearrangements may be made therein without departing from the-essence of the invention.

I claim:

1. In an electrical system of communication, the method of signaling which comprises transmitting code combination signals each composed of.a predetermined number of'elements having different electrical values so chosen that they bear a constant relationship to each other. in each transmitted combination, and balancing the different signal elements receiveda t the receiving apparatus against each other so as to differentiate between true signals which have this constant relationship and other signals which have been mutilated.

2. In printing telegraphy, the method of signaling which comprises transmitting code combination signals each composed of so-called marking and spacingelements so coded as to be in a constant numerical ratio to each other in each letter or numeral transmitted, balancing themarking and spacing elements received at the receiving apparatus against each otherso as to difierentiate between signals in which this constant numerical ratio is present and any mutilated signals or groups of extraneous impulses in which this constant numerical ratio is not present, and then printing at the receiving apparatus only these signals having such constant numerical ratio.

-3. In radio telegraphy, the method of signaling which comprisesformulating signals in a code combination characterized by a predetermined number of positive and negative impulses in an equal ratio in each signal,- transmitting said signals by radio from a radio transmitting station in such manner that said positive and negative impulses produce an equal ratio of distinctive components in each radio signal, receiving said signals at a radio receiving station, causing said radio signal components to establish correspondi positive and negative impulses at the receiving station, and balancing said positive and negative ,impulsesagainst each otherlat the receiving station so. as-to dif re tiate; between truersi nal and signalswhichlhave been mutilated by atmospheric conditions.

4. In printing telegraphy, the method of signalingwhich comprises converting signalsfrom a conventional five unitcode into signals of a second code. by the addition of signal elements in such manner .that the components of each converted signal ..are maintained in .a constant numerical ratio,;tra-nsmitting such signals in this second code to a receiving station, utilizing this constant ratio characteristic at the receiving station toqdifferentiate between mutilated and unmutilated signals, and converting the unmutilated signals back into said conventional five unit code for, printing.

5.1In radiotelegraphy, the method of signaling which. comprises transmitting codesignals from aradio transmitting station on a single radio channel, said channel being composed of different classes of components maintained in a fixed ratio in each signal, receiving said signals at a radioa receiving station, and testing the signals received at the receiving station by a differentiating operation wherein signal components of one class act in opposition to signal components of another class todetermine the presence or absence of said :fixed ratio.

16. In an electrical signaling system, the combination of transmitting apparatus operative to transmit code combination signals composed of elements having .different electrical values so chosen; as .to bear a constant numerical relationship to each .other in each letter or numeral transmitted and receiving apparatus adapted to receive the signalstransmitted from said transmitting apparatusand also receiving mutilated signals and extraneous impulses, said receiving apparatus being operative to differentiate between signals which have thiszconstant numerical relationship and those which do not, and comprising meansfor. automatically transmitting a special signal back to said transmitter upon rereceiving a mutilated signal not having this constant. numerical relationship.

7. Ina telegraph system, the combination of transmitting apparatus operative to transmit code combination signals on a single channel each composed of a fixedsnumber of elements having different electricalvalues so chosen in a constant numerical ratio that the resultant signal of each letter has a predeterminedelectrical value, and receivingapparatus adapted to receive the signals transmitted from said transmitting apparatus and operative to differentiate between signals having such predetermined electrical} value and any mutilated signals or extraneous impulses not having this predetermined electrical value, said receiving apparatus comprising means for auto- ;matically transmitting aspecial signal back to said transmitting apparatus upon the. reception of a: mutilated signal.

8. In aradio telegraph system, the combination of .a radio transmitter comprising means for establishing;signalszcharacterized by a fixed ratio of positive and negative impulses in each signal, means fortransmitting said signalsby radio over a single radiochannel in such a manner that said positive and negative impulses produce the, same fixed ratio of difierent components in .each radio signalcorresponding to said positive and negative impulses, and a radio receiver receiving said signals from said radio transmitter comprising means for converting such com- ;ponentsoithe radio signals backinto correspond- 55 iiasm s ivelandine et ve impu s s-means:operative to test the converted signals for said fixed ratio of positive and, negative impulses, and means for automatically transmitting aspecial radio signal from said radio receiver to said radio transmitter upon the reception at said receiver of a mutilated signal not having such fixed ratio of positive and negative impulses.

9. In an electrical system of communication, the combination of means for converting signals from a first code into signals of a second code in which the components of each signal are maintained in a constant numerical ratio, means for transmitting such latter signals, and receiving apparatus comprising means for receiving and. testing said latter signals to determine if their components are in said constant ratio, and means for converting the tested signals back into said first code.

10. In a radio telegraph system, the combination of means for counverting signals from a conventional five unit code into signals of an eight unit code in which each signal is composed of a predetermined relation of positive and negative impulses having a total potential of zero, a radio transmitter for transmitting said latter signals over a single radio channel, a radio receiver for receiving said latter signals comprising means for testing the received signals for said zero potential to determine whether the signals have been mutilated in transmission, and means for converting the unmutilated signals back into said conventional five unit code-f or operating a printer.

11. In electric signaling apparatus for converting signals from a first code into a second code in which a fixed ratio of electrical values is maintained in each letter transmitted, the combination of a first group of conductors adapted to have different current values impressed thereon corresponding to said letters as coded in said first code, a second group of conductors adapted to have different current values impressed thereon corresponding to additional signal elements employed in converting the letter signals from the first code to the second code, supplementing relays for governing the current values impressed on the conductors of said second group, and testing relay apparatus responding to the current values impressed on said first group of conductors during the transmission of each letter for controlling the operation f said supplement.

. ing relays.

12. In a transmitter for a radio telegraph system, the combination of a transmitting distributor comprising a first group of contacts and a second group of contacts, apparatus responsive to a perforated signal tape for impressing different polarities on said first group of contacts in code relation for each character transmitted, polarized relays for impressing different polarities on said s'econdgroup of contacts, a bank of resistors connected with the contacts of both groups, and means including a relay responsive to the current flow through said bank of resistors corresponding to the particular character to be transmitted for causing the operation of said polarized relays in sequence until the polarities impressed on both groups of contacts are in balanced relation.

13. In a transmitter for a radio telegraph system, the combination of a transmitting distributorcomprising a group of contacts, apparatus responsive to a perforated signal tape for impressing different polarities on said distributor contacts in code relation corresponding to the difierent letter characters to be transmitted, relay apparatus adapted to be actuated in the event that the same polarity is impressed on all contacts of said group in a single letter signal, and means.

responsive to said relay apparatus for transforming such signal by changing the polarity impressed on one or more of said distributor con,- tacts.

14. In a radio telegraph'system, the combination of a radio transmitter for transmitting signals each composed of a predetermined relation of positive and negative impulses the total electrical value of which is zero,a radio receiver for receiving said signals comprising integrating means for testing the total electrical value of the impulses in the received signals, and a printer adapted to respond to said signals, said integrating means governing the operation f said printer.

15. In a radio telegraph system, the combinae tion of a radio transmitter comprising means for transmitting signals on a single radio channel each composed of precalculated significant and supplementary impulses the total electrical value of which is zero, said transmitter comprising a transmitting distributor through which said impulses are impressed on the radio channel in timed sequence, a radio receiver adapted to receive such signals from said radio transmitter comprising a receiving distributor operated synchronously with said. transmitting distributor, integrating means receiving the signal impulses from said receiving distributor and comprising a bankof resistors through which the total electrical value of all impulses in each signal is tested, a printer adapted to respond to the significant impulses of each signal, and printer control means comprising a relay responsive to the current flow through said bank of resistors for governing the operation of -said printer.

l6. Ina radio telegraph system, the combination of a radio transmitter comprising means for transmitting signals on a, singlev radio channel each composed of several predetermined impulses the total electrical value of which is zero, said transmitter comprising a transmitting distributor through which said impulses are projected on the radio channel in timed sequence, a radio receiver adapted to receivesuch signals from saidradio transmitter comprising a receiving distributor operated synchronously with said transmitting distributor, integrating means receiving the signal impulses from said receiving distributor and comprising a bank of resistors through which the total electrical value of all impulses in each signal is tested, a printer adapted torespond to said signal, printer control means comprising'a relay responsive to the current now through said bank of resistors for governing the operation of said printer, means operative totransmit a warning signal from said radio receiver back to said radio transmitter, and means responsive to said printer control means for causing said last named means to operate. Y

17. In a telegraph system, the combination of a, transmitter including a distributor, a receiver including a distributor operating synchronously with said transmitting distributor, said receiver comprising a first group of polarized relays and a second group of polarized relays each having their windings connected with separate groups of contacts of said distributor, the armatures of said first group or relays adapted to engage in one position with one set of relay contacts normally having one potential impressed thereon and adapted to engage in their other position with another set of.relay contacts normally having another potential eifective thereon, a printer adapt ed to receive signal impulses 'tro'm said latter armatures, and means responsive to signal impulses received on said second group of relays for varying the potentials efiective on the relaycontacts of the first group of relays. 1 18. In a telegraph system, the combination a first signal station including means for transmitting signals each having a predeterminedtotal electrical value, a second signal station including a'transmitter and a receiver, said receiver comprising integrating means for testing thetotal electrical value of the signals received from said first statiomarotary shaft, means responsive to said integrating-means for controlling said rotary shaft, and means responsive to said rotaryshaft for causing said transmitter of said second station to transmit warning signals to said firs station.

19. Ina telegraph system, thecombination of a signal station including a transmitter and a receive-r, said transmitter comprising means for ting signals each composed of elements having different electrical values so chosen that they bear a constant relationship toleach' other'in each transmitted signal, theradiorecei-verof 'eachstation-comprising abankof polarized relays adapted to receive the different elements of each signal transmitted from the other station, integrating means actuated by the signal elements from said bank of polarized relays and comprising'a bank of. resistors through which each signal is tested to determine whether the elements thereof bear theaforesaid constant relationship to each other or whether the signal has been mutilated intransmission, a printer, rotary contact means for controlling the admission of the unmutilated signals fromsaidpolarized relays to said printer, and means responsive to said integrating means in-the event of thereceptionof a mutilated signal forinterrupting the operation ofsaid printer and for causing the associated transmitter to transmit warning signals. r

transmitting apparatus including means for causing the positive and negative impulses to be in aconstant ratio to each other in each of these groups,- and receiving apparatus for receiving said signals comprising means jointly responsive to the number of said positive impulses and to the number of said negative impulses in each signal for difierentiatingbetween code combination signals which have this constant ratio and other mutilatedsignalswhich do not. i

23. In an electrical system of communication, the method/of signaling which comprises trans mitting code combination signals from a transmitting station even a single channel, a pluralityof' said signals being composed oftwo kinds of elements having different electrical values-so coded as to bear a constant relationship to each other in each of said code combination signals, receiving said signals at a receiving station-distin-gaiishing at said receiving station between coded signals having this constant relationship and mutilated signals which do not, and automatically transmitting a warning signal from said receiving station back to said transmitting stationupon the reception of such" mutilated signal at saidreceiving station.

24; In an electrical system of communication, the combination-of transmitting apparatus comprising means for transmitting code combination signals, each of which signalsis composed of a pturality of kinds of impulses which bear a balanced numerical relationship to each other in each of said code combination signals, -and apparatus for receiving said signals comprising means jointlyresponsive to the number of impulses of one-kind and to the number of impulses of another kind for distinguishing between said code combination signals which have this balanced relationship and other mutilated signals which ddn'ot. l ll l 25. In an electricalsystem of communication, the method of' signaling which comprises transmitting code signals eachcomposed of four positive elements'and four negative elements, and subjectingthe/signals received at the receiving station to a differentiating operation wherein the 'positive lelements aot'in opposition to said negative elements to i distinguish between true signals which-'have-this relationship of four-positive ele- 21. Inan electrical system of communication,

the. combination of transmitting apparatuscom, prising means for transmitting code combination signals on a single channel each of which signals is composed of two; kinds of impulses having electrical values so.chosen that they bear a .constant. relationship to each other, and apparatus for receiving said signals comprising means mutually responsive to said two kinds of impulses for distinguishing between said code combination signals which. have ,this constant relationship and other mutilated signals whichdo not.- 7

22 In an electrical system of communication, the, combination of transmitting apparatus for transmitting code combination signals on a single channel each of which signals is composed of groups. of positive and negative impulses, a plumen-ts and-four negative elements, and other mutilated signals which do not. 1

26; In'anelectricalsystem of communication, the'meth'od ofsignaling which comprises transmitting code combination signals each composed of eight elements madeup of so-called marking and spacing elements so coded as to be in a constant numerical ratio to each other in each series of eight, andsensing the marking elements and alsothe spacing elements in eachsignal received at the "receiving; apparatus: 50 15 o distinguish b een ue-si na s whi h v is o st nt num r e atioot m rk n and spacing element 'and'oth 'mutilatedsignals, which do not.

2,7. I nyan' electrical system of communication, the combination o transmitting apparatus: comprising meansfor: transmitting code combination signals each of which signalsis composed se es, Qfeigh e emen s made up. of; di fere t KZQQSQEQEQQQE whi h bear a constant relation shirztcea h; o her in each elfies of ei h nd a paratus forzreceiving said signals comprising relay means jointly responsive to said different kindsrof elements in eac'h series Off eight for disnals which have this constant relationship and other mutilated signals which do not.

28. In an electrical system of communication, the method of signaling which comprises transmitting code signals each composed of a predetermined number of positive elements and a predetermined number of negative elements, and testing the code signals received at the receiving station including sensing the number of positive elements and sensing the number of negative elements in each signal to distinguish between true code sigals and mutilated signals.

29. In an electrical system of communication, the combination of transmitting apparatus comprising means for transmitting code combination signals, each of which signals is composed of a predetermined number of marking elements and a predetermined number of spacing elements, and receiving apparatus for receiving said signals comprising a plurality of relays operative to sense the number of marking elements and to sense the number of spacing elements in each received signal, and relay means operative to efiect a relative valuation between the sensing established by the relays responding to the marking elements and the sensing established by the relays responding to the spacing elements, whereby to distinguish between true code combination signals and mutilated signals.

30. In an electrical system of communication, the combination of radio transmitting apparatus comprising means for transmitting code combination signals over a radio channel, each of which signals is composed of a predetermined number of marking elements and a predetermined number of spacing elements which bear a constant relationship to each other in each transmitted signal, and radio receiving apparatus for receiving said signals comprising a plurality of polarized relays operative to sense the number ofgmarking elements and to sense the number of spacing elements in each received signal, and relay means difllerentially responsive to the positions of said polarized relays for distinguishing between true code combination signals which have the aforesaid constant relationship, and mutilated signals which do not.

HENDRIK C. A. van DUUREN.