US2453659A - Secret telegraph signaling - Google Patents

Description

- 2,453,659 H. J. J.\M. DE REGNAULD DE BELLEsclzE SECRET TELEGRAPH SIGNALING Nov. v9, 1948.

Filed Dec. 21, 1942 2y sheets-sheet 1 "f i fT y 2,453,659 H J. J. M. DE REGNAULD DE BELLESCIZE SECRET TELEGRAPH SIGNALING Nov 9, 194s.

Filed Dec. 21, 11942 A 2 sheets-sheet 2 Patented Nov. 9, 1948 2,453,659 SECRET TELEGRAPH SIGNALING Henri Jean Joseph Marie de Regnauld de Bellescize, Saint-Germain au Mont-dOr, Rhone, France, assignor to E. Gutzwiller & Co., Basel, Switzerland, a Swiss company Application December'zi, 1942, serial No. 469,684 In France September 5, 1941 section 1, Public Law 69o, August 8,1946

Patent expires December 12, 1961 (Cl. Z50-8) l Claims.

My invention relates to telegraph methods and systems wherein means are provided to secure a secret service by permuting at the transmitter the successive code elements of unit length `combined so as to form telegraphcharacters, and by restoring the normal order of these elements at the receiver.

In my prior U. S. Patent No. 1,612,101 I have described an electric transmission system comprising two machines operating in cooperation, the first one being an automatic keying device which alters the telegraph code while the second is a printing machine adapted to operate in ac# cordance with the altered code. Such a system however involves a number of drawbacks. In the rst place its operation becomes uncertain as soon as the unit elements are disturbed by statics and/or by fading; in such a case the current generated by each element; in the receiver varies at random and the effect to be retained to represent the sign becomes undetermined; for instance if the said effect is the final intensity of the received current, it may occur that the only part of an element which has undergone a serious disturbance is just the end thereof, in which case this element becomes unidentiable while it would have been satisfactorily read by means of an undulator. Moreover a given signalling apparatus is unable to match any kind of service and its keying speed cannot be adapted to the highly variable transmissionA conditions. Finally the synchronizing and phase adjustment are slow.

One object of my invention is to secure a secret telegraphic service over the link connecting two wire networks supplied with keying and recording devices of any kind, provided that their respective telegraph characters may be divisible intosuccessive unit elements having the same duration. Therefore, each signal may be in plain or ciphered language and the kinds of its unit elements are not limited to two as in the Morse and Baudot codes; and the common duration of these elements may be varied at will by the operators as explained below. This is'obtained by synchronizing the frequencies or rhythms of the signalling system, Wheatstone or Baudot, for instance, and of two pairs of distributors, one being adapted to control the modulation at the transmitter while the other collects electric current issuing from the receiver. These two groups divide the time into intervals which coincide with the durations of the successive unit elements issued from the signalling device. The transmitter pair comprises two distributors, the rst one deliverthe incoming elements to devices,`such as condensers, which store their respective effects,l while the second one collects the said effects ina different or-der and applies same to the modulator. The change in the order may be varied at will by changing the connections between the two distributors. The receiving pair is identicalr except that its internal connections are so arrangedthatA when its inlet distributor receives the elementsl in the altered order chosen at the transmitten'its outlet distributor restores the normal order before supplying the elements to the recording or printing apparatus.

Another object of my invention is to devise the secrecy apparatus so as to ensure better immunity against disturbances than usual recording systems, undulator for instance. The secrecy appa-- ratus has therefore to clearly define the effect which is to be retainedI at the receiver responsive to each code element in order that the latter may be restored at its normal place. This is obtained by deriving the said effect from the whole of the detected current corresponding to the element, or at least from a part thereof as important as permissible with respect to the' accuracy of synchro'- nism between time divisions of distributors and keying, The distributor pair at the receiver is therefore provided with an additional distributor which collects the detected current during the'l largest possible portion of each element, the quantity of electricity supplied by said current being stored in a condenser and the effect designed to:

represent the element being the voltage of the condenser when it has thus been charged.

Pursuant the above object, a preferred form' of my invention consists in combining the methodt automatic handling of received signals will now enjoy better conditions under' Statics and fading than those allowed of by the lecture of an un,-

dulator tape, instead of much worse conditions as it previously happened in secrecy systems. The

` said signalling method, which may be carried out by transmitting the unit elements on frequencies F-l-f, F-f, and eventually F,y comprises managing the receiver so as to translate these elements" into detected currents' +I, or 1, o'r zero, re"l f spectively, and Statics stronger than the signal wave into currents varying at random between +I and -I.

3 condenser at the end of any one of the unit time intervals for determining the effect responsive to this timelitevl cannot exceed a given amount of the normal chargedue to a correct sign. `Consequently, the said method also comprises comparing the charges successively collected from the Iadditional distributor to suitablethresholdsr.l .1.1ey.ft.rt ttsint from test te another- (2)v the, different keyingwspeeds are so selected fighe. corresponding durations ofv elements are 'multiples of a given time unit; v(3) the phase rsltionabetwten thekeysand dit.triltllttfs.0 f .the '11th thatthe .transitions between code eltrrltrats,Y with repetitions 'at thel more rapid speeds..

v her object or invention is to permit anges in the. keying Speed. It Wi11...be Observdthat the ..mens ab0ve. refe.rred to. .1mdr.; i?) and .(3) .imply .that Vthe kering Speeds derived frorn a common time division. This De 1itS..tQ-.Srr 1.chrfmize the driving. motors ofthe distributors or of the keying devicesdisp` ver tlrewire telegraph network, lby means Qf .elettrlaurents or hertzien. Waves modulated in acordancewiththe saidtime division. The keyingspeed may vthus Vbe changed without any rersrnchronizingoperation and even therevv occurs no lossoi' s ynchronism if, through anymistakgthereceiver is adjusted cna keying speed diierentwfrom the speed actually used at the transmitter,

The wavesorcurrents adapted to synchronize this keying devices eventually scattered on the sending telegraph network as well as the receiver distributors, are issued from a central place, such as the radio station. and they are 'modulated in accordance with the time division corresponding to thedistributor set of this station. The said waves or currents may be independent-pilot waves, or v.they may be the signal wave itself according toja method wherein the transitions between code elements rare caused toproduce unidirectional impulses which in turn contro1'the speed of the driving motors to beA synchronized.

vStill a further object of my invention `is to shorten the operations by means of which keying devices and distributors are 'brought into synchronism. According to the known methods'theperiod of the synchronizing wave or current should be equal to the duration ofthe 'groupsof unit elements within lwhich the elements order is permuted for secret purposes.v And since the/numn of elements in each group must be rather highin actual practiceto avoid ,d eciphering for instance "n=12), this period "is relatively large and getting locked synchronisms by means of such a wave or current would be rather slow. Acc'ordig. to 'my invention-the :synchronizing wave or current is'modulated with a much shorter period, preferably equal to the duration of the code element at the lowest keying speed whereby t synchronisrn is rapidly obtained. But with such a synchronizing method a distributor may be synchrnized at anyone of n angular positions with respect to the master distributor or keying device only ithese n positions is correct. In

' order to `permit accurate adjustment, my inven- Thus, the received signal is restored tion pr ovides that the stators of the synchro- Vnized apparatus may be manually adjusted as to their angular relations.

Iosum up, my invention secures a secret radiotele'gra'ph'i'c service only bound to make use of code characters divisible into unit elements of given length. At the transmitter, the ciphering device admits the incoming series of .such elements tsstrhtljcttrdng. .t .-.ttlegrtpaqdts @any sind indffeftritly. permettant. distribus these elements.. inta 'groups containing la Vdefinite number/af them.. .permutas their. order, .in each grua'trld delivers them t0 .the modulatorand to the link which connects the wirenetworks.

atfthe lowest'keying speed are A: :tn'cident At the. receiver; Where the. Signal Wave mar-...b injured ,byfstatics and. 0thtr. inttrferer1cs: each unit. element is .individually .restored .to the vStartda13d.. f9rg required. for dcipherins Operation-sbr meent. Q f an accumulation. efiect Substantially embratingrits Whole durtion.. then. the'series.; of Standard eftts .11s,separated into groups...corre spondng .wththose atthe transmitter, the ef.- fetsfarepermutated ,aeanpn each "groupso .as to recover their vnormal order, and `finallythesignal current is `delivered to a Msuitable recording device- Y... y. YThe advantages secured by this system are obvious; hitherto barred byv interferences, secret radiotelegraphic jservijce will-'become '-possilole, be'- cause thesignal current isrestored into the standard 1form required by, automatic cipherin'g. At'- tempts to unauthorized deciphering will. have to face an ,undetermined problem, due to the lackand so on moreover,y such permutations are varying at .random owing'tothe changes "occurrin'gintelegraph characters aswellras' in phase relations between `characters and igroupa and their "Ip'ossible numb'er may 'be increased Tat will'bymer'ely enlarging the groups. wlilch` are' 'fr'e'e'd 'fr'mfa'ny limitation "since"'ii'dependentftif-fthe 'telegraph codes;y the; recited 1'2'elem`ents "groups "authorize service. of high qualityis'putfat tliev disposait thepublicby merely'encouragirig'him'tol monrsi'gnalli'ng"apparatus matching' his neds'and resources, irom'themost expensive 's'ets tothe telephone. 'Together with this coriditinfairuh'- damental` one since designed vvto"`vul'garize"the securing the secret transfer of the series of varied A5 messages directly exchanged between their customers'.

In other terms, the present invention discloses the indispensable intermedium between wire networks through radio channels.

In the annexed drawings:

Fig. 1 is a diagram showing frequency or amplitude variations of the radiated wave at two keying speeds.

Fig. 2 diagrammatically shows the distributor set at the emitter.

Fig. 3 illustrates the distributor set at the receiver.

Fig. 4 is a. plan view of a double distributor set at the receiver.

In Fig. 1 the telegraphic signal represented is the letter u according to the Morse code (two successive dots and one dash). The ordinates represent amplitude or frequency variations respectively, according as the radiated wave is modulated in amplitude or in frequency. t is the time unit controllingtime division. Curve a corresponds to the lower keying speed and curve b to the higher speed. The speed ratio is equal to 2.

'It will readily be understood that the number of diierent speeds may be varied at will. For instance there might be provided a third speed wherein the duration of a dot would be 3t or more. On the other hand, the duration of a dot could be 2t (as in curve a) at the higher speed and 3i at the lower one, the speed ratio then being fractional and equal to 3/2. It kwill also be understood that the invention is not limited to codes based on combinations of two different elements, such as the Morse code, but may also be carried into practice with a three-element code,`for instance with a code using frequency modulation above and below a basic value F, the three elements then corresponding to the frequencies F-f, F and F+f.

In Fig. 2, I designates a master motor rotating at constant and stable speed. The said motor drives two sets of transmitting distributors 2, 2 and 3,3' through gears 4, each distributor comprising a rotating brush cooperating with fixed sectors. In the example shown, which corresponds to the case of Fig. 1, the speed ratio between 2, 2 and 3, 3 is 'equal to 2. Motor I also drives a distributor 5 which synchronizes through a controlled distributor 5' another motor 6 adapted to drive'keying devices 1 and 8 through gears 9, the speed ratio between 1 and 8 being equal'to the speed ratio between 2, 2' and 3, 3', i. e. to 2. By means of different lines 5"5', the master distributor 5 may simultaneously control in the same way other keying devices of any kind scattered over-the telegraph network connected to the radio-transmitter; provided that all of them work according to the same time division, they may use various telegraph codes and speeds.

Motor I may also drive another distributor I which modulates a pilot wave adapted to synchronize the receiver apparatus when the signal wave is not used for this purpose. The pilot emitter is indicated at II. Distributors and III operate with a very short period, which is preferably'equal to the duration -of the code element at the lower keying speed, i. e. to 2t in the case ofFlg. l. As it has been explained, this permits rapid synchronizing of the controlled motors. In order to bring the time divisions of keying devices 1 and 8 into coincidence with those of distributors 2, 2' and 3, 3' respectivelythe phase position of. thestator at distributor 5' may be adjusted at will by means of a manual handle I2. f

A two-way switch I3 permits operation either with keying device 1 or with keying device 3. Current impulses from the operative keying device are transmitted through a switch Ila to an amplier I4 the plate circuit of which is provided with a potentiometer I5 so adjusted that the voltage difference betweenits terminals is v1 or +111 responsive to operation of the keying device.

One terminal of the said potentiometer is com nected to a two-way swtch I6 whereby voltage differences may lbe applied to the rotating brush of distributor 2 or 3, the xed sectors of which are individually connected to a number of con densers I1. The other terminals of condensers I1 are connected in parallel with the second terminal of potentiometer I5. Due to this arrangement, each condenser l1 receives a charge -111 or +01 according to the kind of element collectedby the corresponding sector. Of course correct operation requires that motor 6 should be properly synchronized and adjusted and that distributor 2 (or, respectively, 3) should be in operation when keying device I (or, respectively, 8) is operative.

The sectors of distributors 2 and 3 are also individually connected with a set of six bars lli` and there is also provided another set of six bars I9, at right angles with the former. Bars I9 are respectively connected with the six sectors of distributors 2 and 3. And in each half of setA Il every bar may be connected by means of a removable plug 20 with any bar of the corresponding half of set I9. It will easily be understood that the rotating brushes of distributors 2' and 3' collect the electric charges of condensers Ilin an order which depends upon the respective positions of plugs 20.

The charges or voltages thus collected are led to a two-way switch 2| which permits operation either of distributor 2' or of distributor 3 and they are applied to the grid of a tube 22,-thus causing resistance variations in the output circuit of the latter. This output circuit is coupled with an oscillator 23 the frequency -oi whichis thus varied in accordance `with resistance variations within tube 22. There is also provided a quartz-controlled master oscillator 23' and the signal wave is obtained by causing oscillators 23, 23' to interfere in a rectifier 24 whereby this wave assumes in turn lfrequencies F+f and F-f re'- sponsively to voltages +111 and v1 for respectiva ly representing the two kinds of code elements.- It is amplified in 25 and radiated by the aerial 23 together with the eventual pilot wave from emitter II. It will be observed that distributors 2 and l3 have their sectors separated by a dead angle, Le; these sectors are shorter than the angle 4 (or 6D in the example illustrated) corresponding to the division of the circle between the successive elements of each group of n elements. Thel object of this arrangement is to avoid thatow ing to the slight imperfections in the phase re; lation of motor 6 with respect to the master mo-v tor I', `a brush might contact a given sector while the element corresponding respectively `to the last or next sector is not yet finished or already beginning.

cundesers .|12 being: discharged in v.the .fverywshort instant during which the respectivebnishesrof Asaisir'distributors simultaneously vkcontact f. two adprovided; twelve: being; an appropriate number.

`z The-'radiated wave,=which is modulated in fre'- gnencyftheltwo kinds of code elements corresponding to frequencies F-l-f and F- f in theA example-S.hown),is. received by the receiveraerial Zlrtiga) vItzls passed through theknown cirvcuitsZ3-.adapted to ensure selection, amplification.' frequency changing; rfrequency driftneutralisation, amplitude control, etc. And it is-demod- -ulated:.,inx,. so as to transform thefrequency changes :finto voltage changesivz lwhich are applied to atube 3.| adapted to act on the receiver distributorsfandto a tube 32 acting on the synchronizing means which control the receiver motor .33.. Should powerful. statics dominate the slgnahwavein. the receiver, the oscillation. freduency .fat demodulator 3E would provisionally come under the control of; said statics and .vary at iandomifromfF-'f toF-l-f, approximate frontiers o filterslila-whereby voltages fed to tubes 3|, 32 would a-lsovai-'yatv random/from c2 to +122'. rg'lheplate. circuit of tube,32 comprises .a transformerrzufwhich actson the gridof an amplifier tube355-through a push-pull rectifying device l36. Voltage1=varlations resultingy from'the transitions between thegincomingrelements are thus transfimedrinto lunidirectional :current impulses thexplatecircut of tube 35. These impulses are applied to .a :rotating commutator 31 controlling an additional exciting lwinding 3B cooperating With-motor33. As clearly-shown in' the drawings, commutator 31 comprises a numbergof pairs of sectors 31a?, 31h, the sectorsof `each pair-being in non.-adja-centzlelation.` The said sectors are. respectivelyconnectedv to one andthe other terminals 4of'wincling f381through sliding brushes while'its'central point is connected with the plate circuit ,of -tube 35. Whenl motor 33 rotates sin synchronism -withythe time division of the incomix ig.e1ement 5,A the brush .31e connected tothe plat-e oflllbef is, on thedead part..between sectors 11a and 3112 (position-illustrated in Fig. 3) when nomment impulse is delivered-by tube 35 and winding:4 3851s inoperative. But -as soongasgmotor '-26 leadsor, respectively, lags; current impulses are transmittei to asector 31ay or, respectively, A311) and winding 3 8 acts to-` increase or, respectively, to reduce -thevexciting'iield whereby the speed is corrected. i Ofycourse the-,naturall speed'ofgmotor 33 should be adjusted as exactly as possible by-jrneans of the emain exciting. winding A33a' to reducegspeelcorrections to a minimum.

Commutator ..31 is so arranged that it-may; effect one speed correction for each element at the lower keying speed. At the higher speed one current impulse is inoperative between two successive?. airspf sectors31a, 31h-which is without any inconvenience. When the .synchronizing isI ensured by means of.' a pilot wave.. the naar is .directly `applied@ commutator'fl afterdemodulation-` `Voltage,varia 'onslfrom amplifier tube .3.`| .are lcd .to a` two-way switch; 39.and thence. tcv one or the other of la. pair oflrotating'` distributors .40, 4| respectively .adaptedfto-operate at the lower and at the higher keying speed. The rotor of each1; cglistributar,r 40;. `for. instance, comprises @two nouns otr three :sectors 10d; ,1 i027,v 148e. l*Sectors* -Miafv arie f connected by a1 slip'+ring.;,andr brushearf rangement-I with switch 39; sectors 40h arexconnected inthe ,same manner with'another/twofway switch. 1-42 sectors: kMic .Hare y:connected fwith` the anode source of tube 3|'fzt'ogether .withonepmte of three condensers 43a;43b.:and:43c,:,theother plates r.i ofrwhich `are :connected toyfixed fbrushes contacting distributor 40 .at 60 from-eachother.

Distributor 40, for instance, is so'timed thata sector 40a comes into contact ywith va..brush;..cor responding to a condenser (43b'ipin1A the. casejillustrated) shortly after the .beginning ;,of-: a. codeajelement. The quantity of electricity deliveredfgby tube 53| .responsive to this sign is,thus.-storedfin condenser 43h. When the element .is..fended, or preferablyrfshortly before, condenser 4,3b1cooper`- ates wit-h a sector.-Illb.,=.wl:iereby` the-voltage@ `re., sulting'irom its charge isi-:applied to1thegrid;of a, tube 1.45. ,Condenser .43h .thereafter cooperates with-.a sector 400i whereby itl isgdischarged-fand ready. to receive afresh chargeresponsive man otherincoming element. Sector 40a isgsomewhat smaller than 6U by matter offsafety against slight timing imperfections; sector` Aub; extends-over?, i. e., the angle corresponding to the duration of an element; and sector 40e is'somewhatvr longer than .60` to bring thetotalangmar. extension of the. sector group to 180",l i. e. the anglecorresponding tothe duration ofvthree elements. It-.will easily .be understood thatrcondensersa, 43h-and 473e `operate in succession.

.Distributor 4| is quite similar to distributor-4 0, vwith sectors Ala; 4;lb -and ,4|c and condensers lilla,v .44h-'and 44e. Sinceit v.correspondsito lthe higher vkeying ispe ed -,xit.isA rotated at ltwice, t lie speed of distributor` 40, which is indicated'byga double arrow while the latter has a simple arrow. vIt `will-be observed that commutator '31, thoughedjusted to i indiiierentlyl correspond to both keying speeds, rotates at thesame Ispeedas distributor 4| (which corresponds to the-higher keying speed)A because one-revolution of these distributors indifierently .extends over-`4 six ele-4 ments atthe higher speed orover threeelements at the lower speed.. But of4 course .ther constructional arrangement,` couldlfbe different.v The drawing very diagrammatically shows in dashed lines. `the mechanical connections .between :motor 3 3 andcommutator 31. or distributors vMl and,

Asabove explained, the cumulative eii'ectfrepresenting aV vcode element, which eiiect 'is the chargeof acondenser 40a to vAlle or filato-Ale, acts `on thegridof tube 45. 'Iheanodecircuit of .said Vtube controls al two-contact relay 46 which in turn/.controls .the grid bias of a-tubeAL '.In

my.afQresa1d..U.-s. Patent 2,176,168, -I have ex,- pl'ained. how in frequency modulation signalling theQcumulative eiect produced by Statics curr rents,.-overthe'duration of each unit sign cannot exceeda .definiteamounty say: forty per.-cent,of theeffectsv normally produced by undisturbed code signs,. provdedv ythat .the r,modulation index fT, that. isto say, the ratio ofi thev frequency changes ftolreyingfliequency.%T, be atleast-equal. to 5 fir-6.A yThis maybe provedthrough probability considerations by comparing over. thef'said duration Tv (T={t,vcr T- f21f according-tothe keyingspeedl ori-the .one hand the norma-l charge :supplied vat the anode circuit of tube'll'bythe current I which corresponds to voltages vzzand frequency changes f,- on ther other hand'the charges "supplied f .by Statics currents .varying at randcrn'from '-I `to +I. 'U designating'thenal voltage reached in cumulative devicesA suchCas condensersia:tornooi-1:44a itof Mcresponsiveito the normal charge IT, relay 46 is `therefore adjusted to close its contacts 46a or 46h only when the variable bias u of tube 45 respectively exceeds +0, 4U or falls below -0, 4U. Thus, the anode current of tube 41 may only assume over each time interval T the one of three definite intensities i1, iz, is, according as contact 46a is closed, or contact 4Gb, or no contact at all; and the two ilrst events certainly denote the reception of unit elements F-l-f or F-f, whereas huge statics as well as fading will certainly cause the third event. Consequently, marks of length T corresponding to i1 or i2 must be deemed correct when occurring in a two-sign code transmission, whilst marks is surely denote an uncertainty to be automatically discarded at the final stage of the reception. With a code combining elements of three kinds, corresponding to frequencies F-l-f, F, F-f, marks iria must again be trusted, but now marks 'is indifferently denote the correct unit sign F or any injured element; the uncertainty is not fully avoided, but instead of concerning all elements" at random it only affects one of them, whereby it may be withdrawn by repeating the signal.

Current variations from the anode circuit of tube 41 therefore reproduce as accurately as possible the elements radiated by the emitter, for these elements have been restored into their standard form after an automatic analysis of the detected current which is highly preferable than estimates practicable on an undulator tape. But these elements are still in the altered order chosen at the emitter for secrecy purposes. To restore the correct order, the said current Variations, transformed into voltage variations by a resistor 4B, are brought to act on distributors similar to those used at the transmitter and operating in a similar Way. These distributors therefore need no detailed explanations and will be very briefly described below.

As at the transmitter there are provided two pairs of distributors 49, 49' and 50, 50' one for the lower keying speed, the other for the higher, each pair comprising an inlet distributor 49 or 50 whereby voltage variations are stored in condensers 5| as electric charges, and an outlet distributor 49' or `50 whereby the charges thus stored are collected in an order which depends upon the positions of plugs 52 connecting two sets of bars 53 and 54. The only difference, which is of mere constructional character, is that in each pair the distributors are concentric instead of being adjacent. Switches 55 and 56 permit operation with any pair of distributors at will according to the keying speed used at the transmitter.

It will be understood that if the plug arrangement on the set of bars at the receiver and at the transmitter are identical, the order of the elements is restored provided, of course, the receiver and transmitter distributors are not only locked into synchronism, but also brought into correct phase relation since the synchronized machines may run at a number n of relative positions (six in the simplified example illustrated), oneonly of which is correct. As in the case of motor 6 the proper phase relation is obtained by manual adjustment of the distributor stato-rs.

Fig. 4 diagrammatically shows a possible construction for the receiver distributors, commutator and associated parts. Motor 33 drives two shafts 51 and 58 at two speeds in the ratio 2:1. Shaft 51 (low speed shaft) carries distributor 40, with the corresponding slip rings, and distributors 49, 49' which are in the form of rotating brushes cooperating with two concentric sets of sectors carried by a plate 59. The connections with the said sectorsare effected through slip-rings carried by a shaft' 50 which is angularly adjustable by means of a handle 6I. The high speed shaft 58 is similarly arranged and also cooperates with a plate 62 carried by a co-axial shaft 63 adjustable by means of a handle 64, but the said high speed shaft 58 also carries commutator 31 with the corresponding slip rings.

VFinally the voltages collected by the operative outlet receiver distributor 49' or, respectively, 50' Fig. 3) are applied to the grid of a tube 65 which controls the printing or recording apparatus 66.

It should be understood that the above description has been given merely by way of example and that it does not limit the scope of my invention, the details of which may vary within the ambit of the appended claims.

I claim:

l. In telegraph signalling based on combinations of unit length impulses, the method of automatically securing secret correspondence along a link interconnecting keying and recording devices operating in compliance with their own telegraph codes, which 4comprises admitting signal currents from one of said keying devices, controlling said keying device to keep its unit impulses in step with the unit intervals of a predetermined timing; and carrying tout the following similar operations at both terminals of the link: separating like unit intervals into groups, separately storing effects of signal currents occurring during successive intervals in each group, and collecting the stored effects in a changed order, the changes respectively carried out at transmitter and receiver terminals being reciprocal ones, whereby signals are delivered to the recording devices as they issue from the keying device.

2. In telegraph signalling based on combinations of unit length impulses, a system for automatically ensuring communication secrecy over the link interconnecting keying and recording devices operatingv with their own telegraph codes, which `comprises means at the input terminal of the link for modulating control Waves in compliance with a predetermined frequency, a switch for admitting signal currents from one of the keying devices, means responsive to said control Waves forkeeping unit impulses issuing from this device in step with unit intervals of a timing related to the said frequency, means for separating these unit intervals into groups, means for separately storing effects of signal currents respectively occurring during successive intervals in each group, means for collecting these stored effects in an altered order to be used over the link; means at the output terminal for separating unit intervals of time into like groups as at the input terminal, said rseparating means consisting of automatic means for causing divisions in intervals to coincide and of manual means to bring like groups of such intervals into phase coincidence, means for separately storing elects of currents received over successive intervals in each group, and` means f-or collecting the stored effects in an order reciprocal to that chosen at the transmitter, whereby signals are delivered to the recording device as they issue from the keying device.

3. In telegraph signalling based on combinations of unit length impulses, the method of automatically securing communication secrecy at various keying speeds over a link alternately fed by keying devices operating with their own telegraph codes, which comprises, assigning to each of said devices a scale of speeds at which the reafwegen;

11 sultingfimpulsefrequency is a harmonic' .of a vgiven'lfrequency,l operatingsaid. keying devices' at their assignedspeeds, controlling the phase `of the keying operation to v'keep fthe 'resulting unit vimpulsesatanyof these speeds in step with subdivisions of the'same given frequency, and at .both terminals of the link' practising at anyspeed similar operations Whichconsisidin separating the series of impulses" into` groupsyseparately storing effects' of signal currents occurring during successive.r subdivisions inY each" group, and 'colylefcting'.v the? stored eiectsin achanged order, the .changes respectivelyfcarriedfout at transmitter and'.'receivei'V .terminals being reciprocal ones, whereby signals are delivered at 'theoutput of th'eflink'as they ssuefro'mthekeying devices.

' 4i vIn f telegraph. signalling; based ony combinations of unit length impulses,- a-system for automatically securing communication secrecy along valink.carrying signals' transmitted in various codes 'and keyingspeeds, which comprises keying devices operating accordingto a.V scale of speeds at which :ther resulting impulse-f frequency is f a harmonic i of a fgiv'eri frequency, means for. controlling-phases of saiddevicesfso as to' keep unit impulses-issuing therefrom'atany of said'speeds ini` step 'fwith 'subdivisions ofv the same given frequency; affplurality of permutatorsfor shuiing `the unitimpulseorder at-theinput of the link, @anni` permuta-tor corresponding to onefofy the possible*V speeds -and being operative over a cycle formed'.v by agiven' number of 'time` subdivisions correspondingto this particularl speed; a plurality.v ofA similarA permutators. for" restoring theimpulses A'to theirnormalorder at the otherv endof the-link;y and yswitches forfconnecting at any speed 'ther convenient set of permutators.

5. A system for securing secrettelegraphic service-over the link designedtoalternately connectfkeyingand recordingy devices which utilize inpairs their lowntelegraph.characters all based onsequenoesof code elementssucceeding one anotherat' the Vsame substantially constant frequency,..which^comprises, at--the sending station a-masteredistributor for dividing thetime. into groups of `successive uniform intervals independently oftheA character sequences', means under the controlA of the master. distributor for maintainingY locked synchronisrn` between these time intervals andthe cod-e elements-of the keying` device set in operation, means forA admitting the::signa1 Wave issuediromthis'device, means for.-separating the seriesl of admitted elements intofthe--groups dened by the masterdistribw tor, storage means-to store therespectiveeffects of.` code elements 'inreach` group sequentially, rxieans.- for; lpermuting the -stored effects accordingftothelaw chosen for' ciphering, modulation means for. adapting ther-permutedeffects to transmission over-the interconnection link, means for; effecting this transmission, demodulation meansgfatthe .receiving station .a local distributer forA dividing timefinto groups of .uniform intervals designed-.to correspondwiththose at the transmitterfy in combination automatic means for controlling theflocaldistributer so as -to keep its time intervals inlocked' synchronism with the received code elements and manual means for causing. the phasel of Yitsgroups to coincide with thephase ofgroups determined-atthe other end .distributerffor'separatinglthe received code elementsinto same groups,` storage means. to -store the. respective eiects of code elements in each groupgmeans for permuting the stored .effectsfso as Ito reconstituteth'eir normal iorder, Iand means fordelivering'these effects to the recordingde- `vicefset 'in operation.

Ina-telegraph system,.a keying device. for

Vgenerating .telegraph characters all` divisibleinto successiveunit elementsv having the lsame-given length,'imeans-for periodically separating these elementsinto groupsindependently of the chariactersf. sequences, means fonpermuting theseelements within ea'clrgroup,Y means fortransmitting therseries ofpermuted'elements'from the sendingVA `station to thereceiving station, storage means fon-- accumulating eachreceived element over. its WholeV duration substantially so as f-to `derive a final' effect from thisaccumulation, meanshforrseparating these eiectsintov same groups; :means for permuting again they eiects Within'each .group .so-as to restoreixthem totheir initial lorder, andV convenient meansrfor record-v ingthe-feilects.v p

f7; Ingaftelegraph.system,.a keyingdevice for genera-tingtelegraph characters all divisible .into successive unit-,elements having thesame given length,t means for l periodically' separati-ng. these elements into groups 'independentlyY of the. characters` sequences, .means for-.permuting the. elements Within each group, means .for-transmittingl the'series of permuted. elementsfromthe sending station to the f receiving station, storage meansfon` accumulating each received element over its whole'r duration'substantially so as. to de:- rive a-.nal l-eifect from ythisl accumulation, .means forindividually transformingfthe saidlaccurnulative effects into -standardei-ects by distributing them among three deiinite classes-faccordingto their valuesfwith respect to. the-limits off'these classes, means' forfsepa'ratingthe series of standard veiievctsyintosame." groups, meansv for..per mutingy again :the yeffects Iwithin 4eacvhsgroup. so as tov Vrestore them to their initial --orderf .and .means for-recording the effects.- v l y HENRI JEAN' JOS'ElELM'ARIEl I DE YREGNAULD. DE .BELLESCIZEL y vREFERENCS A`CITED l Tliefollowing 'references "are 'of irec'ord 'in the file of"tl'isfpatent:

l 1,111,695A :[-IOVlaIfd'y Sept/:22; 1914 1,309,176l Ben'- Jol-ys] 1919 1,322,010 Guhe" NoV 18,"1919 '125225775 vFriedman Jan.-13,"1f92'5 s605923" 'Hartley Novf'a 1926 1,645,805- Dowd pcti 11s, 1927 1,703,719 lllnry'l/Iit- "Fbf'26f'1929 y2,110,548-A Fincii Mar. si 1938 21,146,8"7cy `-Z\`:vory'i-:in Feb. 14,1939 2,175,573 Y"Scln'oter Y'Ot. 10', 1939 2,176,168 Bel-lescize Oct 17, 1939 2,281,405 Barrish eval." Apr. 28,` 1942 2,299,388f Hansen ont. 20,"1'942 2,312,897 Guanella et'al l\'/Iai"."2; 1943

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