US2192005A - Method and means for cable transmission - Google Patents

Description

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A. F. CONNERY METHOD AND MEANS FOR CABLE TRANSMISSION Filed May 17, 1958 Feb. 27, 1940.

JLJITJL E E 73% .GE LQQ Feb. 27, 1940.

A. F. CONNERY 2,192,005

METHOD AND MEANS FOR CABLE TRANSMISSION Filed May 17. 1938 2 Sheets-Sheet 2 12 RING 1 KING 2 INVENTOR 141.05,? E GOA/NEW TTORNEY Patented Feb. 27, 1940 UNITED slats-s TEN OFFICE Application May: 17,-1938;,Serial'No; some;

Myinvention relates to improvementsincable transmitting methods and apparatus-, .and.more particularly to methods and apparatus-for precorrecting distortion of. these signals transmitted over long cables. p a

In known cable transmitting systemsrnow in common use the various charactersiare; composed of combinations of positive-andmnegative current impulses andv spaces ;-of no-current, representing dots, dashes and spaces respectively. In-sucha system the dot and dashes a-nd the spaces are representedby intervalsof thesame durationj; Itis apparent that in-such asystem the receiving apparatus will respond difierently depending upon the particular order. of transmission of impulses.- Thus,- some of thezimpulses as received will be shortened and others lengthened, depending upon thenatureof the signals immediately preceding-and following. the particular impulse transmitted. This: resultstin adistortion 'of the received signal impulses. and a consequent limitation upon the speed oftrans mission, so asto avoid too. great-a distortiom;

Inan attempt to overcomeithis disadvantage a method-of transmission has been used wherein eachcurrent impulse was shortenedxby. adefinite percentage and a no current intervalof length depending. upon. this: period of: shortening was transmitted 7 between each current impulse. This latter systemis commonly knownas abeat signal system- However, this heat signalling system does not obviate the distortion. completely and consequently does not solve the problem.

It is anobject of my. invention to providea new method of signal transmission for.correcting the distortion of signals transmitted over a long. cable.

It is a further object of my invention..to.-pro-.

vide a suitable apparatus for transmittingsigrials in accordance with my invention. A,

It .is astill further object'of my; invention to transmit signals of different lengths. and. :posi-v tion relative to the previously; transmittedhsignals to pre-correct fordistortionsoccurringin a long transmission line:

In accordance with my inyentionfoundiffera ent kindsof dots are transmittedldependingline on position relative to previously andjsubsea quently transmitted impulses and diiierentklnds' of dashes are transmitted'correspondingjto the several types of dots in dependence. upon the type of impulse immediately precedingflandfole lowing the dot impulses- By usingthislmethod the signals as originally.transmittedlare distorted in a direction oppositev to .that..di'storti'oncaused in the transmission line andinthisway the signals may be said to be pre-corrected so that upon reception-they willbe of the proper length; .By: use of this system a considerable increase in speed of transmission of the signals over long cables may be. realized.

' While I haveoutlined above certain of the principles and .objectsof my invention a better understanding of the-invention may be had=by a reading ofthe following description with reference to the accompanying drawings in "which Fig; 1 il1ustrates several curves used inexplaining the principles of'my invention,

Fig. 2 illustrates-the-relativelength-an'd'posi Y tion of dots and dashes' transmitted-in accordance with my invention, and

3 illustrates a'preferred embodiment of myv invention: applied to: areceiven mechanism and the portions of the description of the improved method asindicated.

The code in common use on long: cables: is known as Wheatstone cable'code or'more commonly asicablecode: In this code; the letters of" the alphabet and. other necessary characters are composed ofvarious combinationsof dots, dashes andspaces: A dot is signalled by applying a positive potential to the cable: conductor for-a certain-. interval of time; A dash is signalled byapplying a: negative potential fora similar interval of time; During-the spacingiinterval'between separate. characters; the cable conductor is earthed; When block: signalsor, 100- per'cent transmission, are used, the cableis only earthed'between letters and/there are no earthing periods: between" the dots-and dashes composing, a letter. i

In Fig.1, line 1v isshown in graphic form, the manner'in which the potentialsiareapplied'to the cable when transmitting the letters --A;-B,C,' D and E, using-the block-signal method of transmission. In this system? the separate dots and/on dashes are transmitted in a:- block wheneverthey occur successively in a single word; When the beat signalsare used, a.=-dot, for-eX-' ample, is transmitted .byapplying er-positive .potentialfor, say, 80% of the-dottime andearth-v ing. the cable for the remaining-20%. A-dash is transmitted by applying ainegativezpotential for.80-% :of the dash timeandhas a.simi-lar 20%- earthi-ng: interval. In Fig. 1, line 2. -are--:shown beat. signals astransmitted. The beat-type of signa1s,- when a suitable. amount of--earthing..is used, results in. slightly reduced distortion of the sig-nalQreceivedat thefar. end ofwthe' cabler It will benoticed. thatthere is:' a short earthing relative phase is different. Tests and experi,

interval between successive impulses of the same polarity. These earthing intervals are made too short to actuate the receiving instrument and are for the purpose of preventing too great a charge building up on the cable.

It is customary-to transmit signals into long cables at as high a speed as it is possible to accurately receive the signals at the far end. If the speed of transmission is too high then the received signals will have excessive distortion and errors will result when these signals are translated. While distortion of the received signals may be due to many causes such as imperfect electrical balance when duplex working is used, distortion due to disturbance caused by extraneous currents etc., it has been found that the amount of distortion is dependent to a large extent upon the type of signal that precedes and follows a given dot or dash. For example, a dot that is preceded by a space will actuate the receiving instrument at a certain instant but if the dot had been preceded by a dash then the receiving instrument will be operated at a slightly later instant. In other words, the exact instant that the receiving instrument is actuated by a dot will depend upon whether the previous signal is a space or a dash. In a similar manner, the instant that the receiving instrument is actuated by a dash will depend upon whether the preceding signal was a space or a dot. It has also been determined that the instant that the receiving instrument ceases to record a dot or dash is affected by the type of signal that follows. A dot, for example, that is followed by a space will end later than a dot that is followed by a dash.

Thesignal shown in Fig. 1, line 3 is a typical signal, as recorded by the receiving relay from a long cable. In comparing this distorted received signal with the sent signal on line 2, it will be seen that the distortion is as previously described.

In accordance with my invention the type of signal transmitted into the cable is modified in such a way as to anticipate or precompensate for this distortion and in this way reduce the distortion of the signal recorded by the receiving instrument.

In my invention, a dot, for example, instead of always being transmitted in one certain way, may be transmitted in any one of four different ways. In Fig. 2 four types of dots are shown and indicated as type A, B, C and D. Type A, for example, will be transmitted when the preceding signal is a dot or a space and the following signal is a dotor a space. Type B will be transmitted when the preceding signal is a dash and the following signal is a dash. Type C will be transmitted whenthe preceding signal is a dash and the following signal is a dot or a space. Type D will be transmitted when the preceding signal is a dot or a space and the following signal is a dash. Four types of dashes corresponding to the types of dots are also shown. Type A will be transmitted when the preceding signal is a space or a dash and the following signal is a space or a dash. Type B will be transmitted when the preceding signal is a dot and the following signal is a dot. Type C will be transmitted when the preceding signal is a dot and the following signal is a space or a dash. Type D will be transmitted when the preceding signal is a zero or dash and the following signal is a dot. The duration of marking of a type A dot in the present case is only 50% of that of a type B or full dot. The type C and D dots are long but the ments indicate that the shortest dot or dash should be about 50% of the length of the longest dot or dash but it is quite likely that under certain conditions other values will be found to be more suitable. When the letters A, B, C, D and E aretransmitted in accordance with my invention the sent signal will be in accordance with Fig. 1, line 4. The received signal will have less distortion. Experiments and tests indicate that a given cable may be operated satisfactorily with this new type'of transmission at a much higher speed than with the conventional block or beat type signals.

While the embodiment as described in connec-' tion with line4 appears to be the best, it is clear that other systems could be used to accomplish a partial correction of the transmitted signals.

For example, instead of correcting each end of the signal element in accordance with the nature of the preceding and following signal element, only one end might be changed in accordance Witheither the preceding or following element. In this type of system one or more different correcting elements may be added to the start or end of a signal impulse depending upon the nature of the signal element immediately preceding or following it.

Furthermore, it is clear that some other characteristic of the signal, for instance, the voltage may be varied in response to the nature of the preceding and/or following signal impulse to accomplish the desired compensation. Moreover, instead of using only three types of dots and dashes, a greater number could beused to more precisely compensate for received signal distor- It should also be understood that, while I have illustrated a system wherein the method of my invention is applied to a three element code, the principles are likewise applicable to other types of codes. For example, distortion of received signals of a two element code may also be compensated byproper predistortion of the transmitted signals. It is clear that in such a system the characters as received will be distorted according to the nature of the successive signals transmitted. In order to compensate for such distortion of the signals a characteristic of the separate elements may be controlled in accordance with the preceding or following signals t precompensate for such distortions.

A schematic diagram of a preferred form of apparatus in accordance with my invention is shown by way of example in Fig. 3. In this figure my invention is shown incorporated in a respacingor non-operated position. These relays are operated by signals incoming over line Li. I

in accordance with the signals impressed on the line. These relays may be connected to a primary receiving relay such as .a neutral position polar relay in such a manner as to cause current of proper polarity to operate the dot receiving relay R1 to marking position when a dot signal is anoaoos received and to operate the -dash receiving relay.

rent sources are used,.it is clear that'this additional apparatus is used only because "the signals received are too weak toproperly operate the other'separate relays. The reverse signals on the line would operate the relays Ri and R2 in the samemanner iftheywere of sufiicient'strength, and since the particular form of line relay is not necessary to an understanding of my invention it has-not been illustrated. Brushes BRI and BRQ -and the associated segmented and solid rings'represent a developed viewof a conventional-type rotary distributor. Thebrushes are assumed to be revolving at a'very'constant speed and in phase with the received signals, and to travel in adirection from left to right as shown in the drawings.

Segments I; 3, 5, I, 9, etc. of ring I .are joined together and connected to thetongue of the dash relayRz. Both the dot and the dashreceiving relays are shown in theunoperated or" spacing pdsitions that they assume when a zero or no current=signal isbeing received. Segments-I, 3. 5 etc. are all connected to earth through the tongues 20, El and spacing contacts 3o, 3| of dot and dash receiving relays R1 and R2. When brush BR! passes over segment I, a circuit is completed between segment land solid ring 2' and condenser CI connected to solid ring 2 will be charged to the potential that exists between the-tongue of the dashreceiving relay R2 and ground. In the present case since the dot and dash receiving relays are both on spacing there will be no-charge-oncondenser CI. If dot re ceiving relay R1 were marking and relay R2 spacing-then condenser CI would be charged to a positive voltage of, forexample, 120 volts over contact 4Il-and tongue 28. If, however, dash receiving relay R1 were marking then the condenser CI would receive a smaller charge, for example, 60-volts. When the distributorbrushes are operating in'proper phase with the received signals the brush BRI will just be leaving segments I, 3.

fietc. during the center or good portion of the received signal. In other words, the instant that brush'BRI leaves the odd numbered segments will be theso-called pick-up point.

When brush BRI reaches segment 2 the charge on-condensers CIand C2 will mix. Condenser C2 is much smaller than CI, for example, about 94 the size of CI. Condenser C2 will therefore assume substantially the voltage of CI and the voltage of CI will vbe'only slightly altered when the charges are mixed.

The grids of vacuum tubes VI and V2' are-connected to condenser C2 but in series with each is a biasing battery. The grid of tube VI is biased to a predetermined potential, for example, I 30 volts, and thegrid of V2'is biased at higher value by its separate battery, for, example, 60 volts. The effective bias on V2, however, is the sum of the voltages of-the two bias batteries or 90 volts. The type-of vacuum tube used is preferably such that when the grid potential with respect to the cathode'is-negative to a particular value, for

example, 15 volts or more, there will be negligible plate current. When the grid voltage is zero orslightly positive there will be maximum. plate current. In order to prevent'the grid of any tube becoming very positive with respect'to the cathode anddamaging the tube, awery-high resistance Illzmay be inserted in-se'ries with'each grid; With--the=-resistance so .located, as, soon as the grid tendsto draw currenta large voltage drop occursacross the series resistor which I tends to make the-gridless positive. The use of this high resistance: reduces, the tendency of the; condenser torapidlyzdischarge when the grid-is positive.

As previouslyzstatedg' using the potential values outlined above, when :a zero signal is received condenserOI'will have no charge. When a dot is received CI willhave-a 120'volt charge. 7 When a' dash is-receivedCI willhave a 60' volt charge. When the brush passes :.onto segment 2, condenser (32 will be: charged to a. corresponding voltage. The gridlof VI willitend to assume the voltage of. C2 minus- 30 volts' and the grid V2 will tend to assumethe, voltage of 1 C2: minus 90 volts. The action' onthese tubes under'zero, dot and dash conditions-will then be as: follows:

These two tubes VI and'JV2 and their associated circuits constitute storage circuit A, enclosedin broken lines at'the left ofFig. 3.

From the above tableitwill be obvious that when azerosignal is "received over the cable and stored .in circuit A, there will be no plate ,current flowing from VI or V2; When a dot signal is received there will'be plate current flowing from both VI tor V2; When a dash signal is receivedthere will be plate current flowing from VI only.

It should be noted'that. even numbered'segments 2, 6,10; etc. are connected to condenser C2 and tubes Vland V2; and that alternate even numbered segments 4, 8, I2, etc. are connected to C3 and tubes V3 and V4: which constitute with the associated circuit, storage circuit B enclosed inbroken linesto the left in Fig. 3. Tubes VI and V2work together alternately with tubes V3 and'V4. The first signal received will, for example, control tubes VI. and V2, the second signal will control tubes V3" and V4, the third signal will control VI andVZand so on. g

In series with the plate of VI is relay RLI and in series with V2 are. relays RL2 and RL3. In series with V3 is relay RL I and in series with VII are relays RL5 and RLB. The tongues and contacts ofrelays RLI to RLG inclusive, are connected to the segmented transmitting ring 3 in such' a manner as to apply the proper potentials to the various segments of'this ringso that when brush BB2 passes over these segments the dot anddash output relays R3 and R4 will be properly operated-to transmitsignals in accordance with my invention.

Dot-and dash output relays R3 and R4 are of the polarizedrtype and are connected so that when a: positive potential is applied to solid ring 4-dot output relay Ra will be operated. A negative potential on solid ring '4 will operate dash output relay R4. Zero potential on solid'ring 4 will result in neither output relay being operated. Each' of the output relays are equipped with a biasing windingwhich holds the armatures to the spacing side when no ourrentisfiowing through the main I03, I06, I09, I I2,etc. and between each of the long segments are a pair of shorter segments IOI, I02, I04, I05, IIl'I, I08, etc. During the time required to transmit one complete dot, or dash, the brush! BR2 passes over one short, one long and one short segment. In case a dot is being transmitted dot output relay R3 will invariably mark while the. brush is on the long segment and in case a dash is being transmitted, dash output relay R4 will invariably mark while the brush is on the long segment. Whether or not an output relay marks while the brush BR2 is on a short segment depends upon the relative position of relays RL3 and RLS. If both relays are in a similar position, for example, both energized or both deenergized, as shown in Fig. 3, then all the short segments will be dead. If, however, relays RL3 and RLO are in dissimilar positions, for example, one operated and the other unoperated, then all short segments will become live, provided the circuit is completed through relay RLI or RL I, as the case may be, and the polarity of each short segment will correspond with the polarity of the adjacent long segment.

This repeater is provided with circuits for storing two signals at a time. Vacuum tubes VI and V2 and associated equipment constitute one storing circuit and the other storing circuit is composed of tubes V3 and V and associated equipment. As previously stated, the received signals are alternately impressed and temporarily stored on either one storing circuit or the other. Each storing circuit is shown in the drawings enclosed in dotted lines and will be referred to as storing circuit A or B. A signal, for example, will be stored in B while the A signal is being transmitted. While the B signal is being transmitted the .next signal will be stored in A in place of the previous signal.

Although I have shown a repeater in which storage and operation control is effected by means of condensers and vacuum tubes, it is clear that other suitable forms of storage means such as relays or the like may be used if desired. Likewise, a relay arrangement of suitable construction may be used in place of the rotary distributors to distribute the received and retransmitted signals.

It should be noted that ring I is displaced with respect to ring 3 so that the stored signal in the storing circuit may change at the moment that the brush BB2 is in the center of a long segment on ring 3 which is controlled by the other storing circuit. This displacement insures that there will be no breaking up or splitting of the trans: mitted signals.

Having now described the repeater of Fig. 3, a brief description of its operation will serve to more fully explain my invention.

Assume that a dot has been set up in storing circuit A and that brush BB? is on segment I03 and is approaching the center of the segment. Relays RLI, RLZ and R113 will be energized closing their respective contacts. A circuit will be completed as follows: From positive battery to the marking contact and tongue of RLZ, to right marking contact and tongue RLI and thence to segments I03 etc. of ring 3. The current will pass through the brush to solid ring 4 and the polarity will be such as to mark dot output relay R3. The signal output from the output relays is to line L2, therefore, a dot. The exact moment at which this dot will be terminated will depend upon what type of signal follows that dot. If the succeeding signal is a dot or a zero then the preceding dot signal should be terminated just as I soon as the brush leaves long segment I03. If

the succeeding signal, however, is a dash, then the preceding dot should continue while the brush is on the short segment I04 following the long segment. As soon as. brush BRZ reaches the center of the long segment, brush BRI will be touching a segment which will cause a new signal to be stored in storing circuit B. Assume that the new stored signal is a dot. Relays RL4, RL5

and RLt will be operated, closing their respective contacts. Since relays RL3 and RLB are in a similar position, both operated, none of the short segments of ring 3 will be energized, and

therefore the signal on the dot output relay will cease when the brush BB2 leaves the long segment. Had the succeeding signal which was set up in storing circuit B been a dash then the previous dot signal would not have ended when the brush left the long segment. A dash on storing circuit B when there was a dot stored on storing circuit A would result in relay RLG being unoperated while RL3 was operated. The following circuit would be completed: From segment I03 to right tongue and marking contact of relay RL3, to left spacing contact and tongue of relay RLS, to left tongue and marking contact of relay RLG, to the short segment I04 which follows I03. In other words, long segment I03 and short segment I04 are connected together and the dot output relay will continue to mark when the brush BB2 leaves segment I03 and passes onto segment I04.

When the brush passes onto segment I05 dash.

output relay R4 should mark in place of dot output relay R3. The circuit will be as follows: From segment I05 to left marking contact and tongue of relay RLI, to left tongue and spacing contact of relay RL3, to right marking contact and tongue of relay RLIS, to long segment I00. Short segment I 05 and long segment I06 are therefore joined together. A circuit goes from segment I06, to right tongue and marking contact of relay RLQ, to left tongue and spacing contact of relay RL5, to negative battery. Segments I05 and I06 as well as I07 are all connected together and are polarized negatively. The dash output relay will therefore mark while the brush passes over segments I05 and I00. It does not necessarily follow that the dash relay will also mark while the brush is passing over segment I01 because while the brush is in the center of long segment I06 the next signal will be stored on storing circuit A, and segment I01 maybe dis connected from segment I06 so that when the brush passes onto segment III? that segment will be dead and the dot and dash output relays will be spaced by the biasing current in the second winding and therefore a zero or earthing signal will be transmitted.

It should benoted that each long segment has adjacent to it on each side a short segment. These two short segments are permanently strapped together and they mayor may not be connected to the long segment depending upon the relative position of relays RLI, RL3, RL4, RL6. Briefly stated, if there is a dot stored in one storing circuit then the brush BRZ in passing from one long segment to the next via the stored then the short segments will not be con- 75;

nected to the adjacent long segments and the output fr m the rep ater While h brush is passme over them will be a zero signal. e

While I haveillustrated a preferred embodie ment of my invention in the form of regenera tive repeater as shown in Fig. 3, it should .be ,distinctly understood that my invention is v,not limited to that particular arrangement. It is clear that instead of using a repeating system as shown, the impulses from a transmitter could be directly controlled so as to properly actuate a receiver, without distortion. v

Furthermore, transmission in accordance with the method of my invention, may beaccomplished by use of a perforated tape transmitter, or by manual means. If perforated tape is to be used it is merely necessary that means beprovided to make different length and position of perforations dependent upon the position of the ence upon the,

dotor dash to be transmitted relative to the preceding impulse as outlined above. According.- ly predistorted impulses would be transmitted over the line in accordance with the tape perforations. 1

Likewise, if manual keying is to be used, it is merely necessary that the operators control the length and position of the dot or dash transmitted in accordance with the relative location in the series of impulses to be transmitted.

Although I have only illustrated and described a limited number of preferred embodiments of my invention, it should be understood that these constitute merelyexamples of, my inventionand should not be considered as limitations thereof. What I- consider as my invention and desire to protect is defined in the appendedclaims.

What is claimed is:

l. A method of telegraph signalling-to avoid distortion-of received signals whichcomprises transmitting signals as a series of impulses of different nature, and variably controlling the duration of the impulses transmitted in dependpe' of signal impulse preceding and following said transmitted impulse. I

A method-of signalling over a long line i which comprises impressing a positive current impulse on said lineto represent one type of character element, impressing a negative current 1 pulse on said lineto represent another type of character element, grounding said line to represent a third type of character element, and changing the length of the positive and negative character impulses in dependence upon the nature of the signal element preceding and following the character impulse.

' 3. In a telegraph system using a code composed of positive and negative current impulses and spaces of no current as signal elements for signalling over a line, the method of compensating for inherent distortion of received signals due to the type of signal elements occurring s'uc-' cessively during transmission of 'a message which,

comprises impressing current impulses and spaces on said line in sequence to represent the different elements i d ende unonthe n u of he preceding and following character, elements or character impulses in dependence upon the nature of the signal element preceding and follow.- ing the character impulse.

6. A method of signalling in accordance with claim .5, in which the length of the signal impulses is variedby changing the time of initiating and terminating the impression of the signal impulse in response to the character element or space preceding and following the impulse.

. ",7. A method of signal transmission which comprises representing characters of a signal by positive current impulses, negative current impulses and spaces or no current periods as character elements, and variably controlling the length and relative time. relation of positive and negative transmitted impulses in accordance with the nature of the character'elements preceding and following the said transmitted impulse.

8. A method of signal transmission using characters represented by elements of positive current impulses, negative current impulses and terminating periods of no current, which comprises transmitting positive or negative current impulses of one length when the preceding and following character element is of the same type or a terminating period, and transmitting a current impulse lengthened on one end "by'a predetermined amount when the preceding or following character element is of opposite polarity,

elements.

10. In a telegraph system using acode composed of positive and negative current impulses and spaces of no current as signal elements for signalling over a line, means for compensating for inherent distortion of received signals due to the type of signal elements occurring successively during transmission of a message comprising transmitting means for impressing current impulses and spaces on said line in sequence to represent the different characters of a message, and

control means cooperating with said transmittingmeans responsive to the nature of the successively transmitted impulses to variably control the duration of said current impulses to precompensate for the inherent distortion inreception.

11. In a telegraph system using a code composed of positive and negative current impulses and spacesof no current as signal elements for signalling over a line, means for compensating 0 changing the length of the positive and negative I means responsive to the nature of the successively transmitted signals for impressing current impulses of said difierent lengths on said line dependent upon the successively transmitted signals to precompensate for said inherent distortion in a reception.

12. A telegraph system for transmitting signals over a long line, comprising means for applying positive current impulses, negative current impulses and periods of no current to said transmission line to represent signal character elements, and means responsive to the nature of the pre ceding character element and the following character element to variably control the duration of each of said positive and negative character elements.

13. A telegraph system for transmitting signals over a transmission line, comprising means for applying to said line current impulses of one polarity to represent a dot, for applying to said line current impulses of the opposite polarity to represent dashes, and for grounding said line to present spacings, means for applying said current for a predetermined length of time to represent a dot or dash in response to the condition that the signal elements immediately preceding and following it are of the same character or are spaces, and means for lengthening the period of time for which current is applied to the line to represent a dot or dash in response to the condition that the preceding or following character element is of opposite polarity.

14. A telegraph repeater for repeating and re-' generating signals to avoid distortion in reception of signals repeated into a long transmission line comprising a receiving distributor, means responsubsequently stored signal element.

15. A telegraph repeater for repeating signals composed of currentimpulses of positive polarity,

current impulses of opposite polarity and spaces I 15 s of no current as character elements, comprising receiving relay means responsive to received signal character elements, a receiving distributor,

said distributor comprising a segmented ring and a solid ring, means connectingalternate segments of said segmented ring to said relay means whereby signals received may be applied to said segments, means for connecting alternate ones of i said remaining segments to different storage ,circuits, a condenser connected to said solid ring, means for transferring received signals to said condenser and subsequently to one of said storage circuits over said distributor, an output distributor comprising a segmented ring having a plurality of central segments each between two outer segments, means for coupling said output segmented ring .with said storage circuits, means responsive to received signalimpulses for establishing'pQ itive, negative or no current connections to the central segments of said output distributor ring, means-responsive to precedingor following character elements of opposite polarity for causing said storage circuits to connect one or both of said outer segments to said central segment, and means responsive to the polarity established on said output segmented ring segments for operating transmitting relay means to transmit a signal of a length dependent upon the condition of said central segment and said outer segments.

- ALDER- F. CONNERY.

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