US2406384A - Data transmission system - Google Patents

Description

Aug. 27, 1946,

F. s'. KINKEAD ET AL I DATA TRANSMISSION 'SYSTEM Filed Nov. 5, 1942 ,3 Sheets-Sheet l E S. KIN/(EID. DECEASED F. J. SINGER v E. N. SMIT/'l ATTORNEY Aug. 27, '1946. F. S. KI'NKEAD, ETAL 2,406,384

DATA TRANSMISSION SYSTEM l Filed Nov. 5,'1942 z sheets-sheet 2 Ffa. 2

END 0F TENT/l DEGREhE ZONES Aug. 27, 1946.` Y F..s. KlNKEAp ETAL l2,406,384

DATA TRANSMISSION SYSTEM Y y Filed Nov. 5,' 1942 s sheets-sheet s DEG/17E E LAMPS F. S. Kil/READ, DECESED TTORNEY Patented Aug. 27, 1946 UNITED STATES PATENT oFFIcE DATA TRANSMISSION SYSTEM Fullerton S. Kinkead, deceased, late of New York,4 N. Y., by Rita S. Knkead, admnistratrix, Trudan, N. Y., Lawrence E. Melhuish, Glen Ridge N. J., Fred J. Singer, Rockville Centre, N. Y, and Edward M. Smith, Montclair, N. J., assignors to Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New Yorkv,"4 Application November 5, 1942, Serial No.'464,564

An object of this invention is the improvement of systems for transmitting data such as date, represented by plural digit numbers from a rst station to a second station.

p Another object of the invention herein is the instantaneous transmission of electrical impulses corresponding to multidigit numbers which may, for instance, represent observed data from a first station to a second station.

A further object of this invention is the reduction in the number of channels required to transmit electrical impulses corresponding to multidigit numbers instantaneously from a first station to a second station.

A feature of this invention is the dividing of multidigit numbers representing data to be transmitted between stations into a plurality of subgroups of digits` the number of digits in each subgroup and Ithe number of subgroups being chosen in such manner as to minimize the number of channels required for the instantaneous transmission of impulse in accordance with a permutation code to identify the multidigt number.

A further feature of this invention is the separation of a multidigit number into a plurality of subgroups of digits, the assigning of a separate permutation code to each subgroup and the assigning of a separate channel comprising a number of separate conducting elements corresponding lto the number of elements in each permutation code for each channel so as to permit the transmission of electrical impulses corresponding to the multidigit number instantaneously between stations.

Another feature of this invention is a channel comprising ve conducting elements for the transmission at different times of permutation codes dening a single digit number and employing only four of the ve conducting elements and at other times of codes defining-a two- 5 Claims. (Cl. 177-351) 2 digit number and requiring the employment of all five conducting elements so as to separately control apparatus individual to the `single -digit number and apparatus individual to the twodigit number. t

Another feature of'this invention is the disabling of the apparatus controlled in response to the signal elements dening the single digit number when signal impulses intended for the control of apparatus responsive to -the two-digit number are transmitted and vice Versa. These and other features of the invention will become apparent from the following detailed description when read with reference to the associated drawings in which:

Fig. 1 represents a drawing in schematic form showing two observing stations which are assumed to be located at points Where observations are made and translated into data to be transmitted over direct current telegraph circuits connecting each observation circuit with a central station; l

Fig. 2 shows the apparatus and wiring at a single observing station used in observing data at the observing station and transmitting electrical impulses corresponding to the data to the central station;

Fig. 3 shows one set of apparatus at the Ycentral station which is required to decode and record the data transmitted from one observing station; f Figs. 4, 5 and 6 are code chartsA used in explaining the operation of the apparatus per Fig. 2 and Fig. 3. e

General In one of its applications, the invention herein may be used in a 4data transmission system for observing data at one point and instantaneously translating the data into electrical impulses which areinstantly transmitted to a central station. Such systems may be used, for instance, in determining the range and angular position of a target. In one system of range nding, two

4observing stations are located at the extremities 3 the target establishes the line of direction of the target with respect to the base line. The intersection of the lines of sight at the two observingr stations fixesthe, position of the-target.. l

In thejnvention-.herein it is possiblelto trans- Y mit instantaneously and continuously from each observing station to the central station electricalV impulses corresponding to any number from 0 to 2000 to represent any one of twothousand positions within a ZO-degreeangle., Inthissystem, the'circle atthe center of!wlbiclreach.ob

i facility, such as a telephone circuit or a separate Y telegraph; circuit.

The:Y particular degree and` hundredthsfoff;'avdeglieef posi-tionsv Withi-neac-trv ZQedegreer-segmenuas determined bythe lineef sig-ht@ ofthetelescope; directedfat theA .targetv jwi-ll be automatically translated into electrical-f im;-

pulses; whichf aretransmitted3 instantaneously to central jstattlon-l where.- the;.impulsesL are des coded andzthodatafindicated. f

In this'system, it: istobe understood, asfrnenftionedfabove; thatsonef observilzlgfvv station; and one setgofequipment-sucn as Fig,-v 2,-wllfbee1ocatedfat eaohfendofgthe-baseline.. rEwo sets otfequipment suclnas- Figp4 3 fwzi'11 bolo atedfatrthecentralfstafftionf; The. equipment;at:` eachI` observing@stationi is identical. The equipment required for decoding;Vv andi recording the; impulses-freceived Vfrom each observing stationfis identical.V In the-description-to' follow; themannerf in fwhichv one, set,A ot observingP equipment: at. one-V end of` a,` base liney functionsv anda the *manner in which one-setot-deco ding-and.- ;recordingequinment at ,thecerr-V tral stations functions will be described.` Itfisf tof be understood?thatn the; equipment.- at the-second observing4 stations andfth'e corresponding* decode ing;A andrecording equipiment@V at tlcefcentral.sta'A 'f tion functionsinfthe identicalfmannen Refer now to Fig. 2. A telescopeg` rested, at the-target; The particular'ZOsdegree Zone-within` which thef line ,-isfloeatedfisf made; known,:totheattendant at the,- central stationby@ means of a separate telephone or telegraph- .ciri-` cuit. Once thertargetfislsighted th'ef'telescope 2,0 I istcon-tinuously directedat the targeteby thefob' server who will turn the Vernier crajnls 2&2 in

such manner as to maintain Ithe line of sight through the telescope on the target. As the Vernier crankts.; turned;l the telescope isgrotated by meansf of ,fworvm 433rr which Vengagesz with; worm isrigidly secured Ilov-r1rleans of spindle 265.; One complete frotation.. of` the Vernier shaft; turnsftl'ieY telescopev through one degree through gearing havingya ratioY of 369 to 1-. Aspthef'telescope is rotatedr the lradiah horizontal arml 2 01 isIn rotated` with it.,` Ifhey outer endgof radiali arm 20'!r forms` a` bearing and support-'for-vertical shaft 203. A- pinionf 2119.- issecured f-to shaft 208.' inl position.'V to engage ring-.gearA 2 I il: whichfis-rigidlygsecured-t-o a, tripod (notshowrr) usedfto support theobserving instrument and 4its aassociated mechanisms.A

As thefvernier. crank isr turned; the disc or platform. Zlfsupporting the telescope- 2M vis ro.- tated.. Radialv arm 2911s rotated revolving the venticaLshatt 20.8.4 As?y ther shaft 2118i. reveil/fes,Y pinionlii,` engages ring gear 2li). Th'us shaft zal is ii-f.

2ll8,'while revolving about spindle 266'as a center, rotatesalso about its own center.

of the gear 2m to gear 209 is such that shaft 208 rotatesl about, its, own axis.. once while revolving through, twenty degrees, about the vertical axis of the telescope. Secured to shaft 258 are 5-degree cams 2|! to 215, inclusive. The five cams control five followers 225 to 22%, inclusive, which when. actuated by their respective cams supply ground through individual contacts. The 5-degree cams 2| ll to M5 are arranged to close their individual contacts'in accordance with a permuf taticn codesol as to transmit twenty Ydiiferent combinations ofimpulses for each rotation of shaft' Ziii to. identify each of the S20-degree divisions within each of the eighteen sectors into whichA the circle is assumed to be divided. Each of cams 2| l to 2l5 therefore is divided into twen-` ty equal.' segments arranged yto either open or close its respective Contact to provide twenty dif ferent, combinatiensfor each Vrevolutionof `shaft to define eachof theftwentydegrees as; indi- Y n Mounted on thev horizontal crank-shaft are: vefcanisfnumbered, 221: tof2125,y

cated in.- Fig. 6.

inclusiva. lour,` of these. cam-s: 22ltov 224:, inclusive, aren used I-in ltransmit-ting` impulses corre Y spendingL tothe tenths of a degree' within'each' degree.v Thefth camcam 2.2%; is used irroper.` atingl a,- switch the primary function offwhichfis Y Y to keep Ythe degreeI information separateffrom the tenths of,v a degree information. The manner in which this functions will loefV explained in' detail below. At this,L point, however; attention is called to the fact that the same live-conductors 226.119.23, inclusive, which, tal;en,-together, constitute a: channel arrangedY to,- transmit inst-anw,- taneously impulses defining, any of thirtyetwo numbers is used at separate timesto; transmit: impulses. defining any' of the twentyf degrees within aiparticular sector. and anu oftheftenth'sf sf pointed'- of, ai degree within; each degree. IL outthat in ordertctransmit twenty-A different' sets of impulses corresponding; to-twenty dif.- ferent degreesi-and ten different-.sets ofyimpulses corresponding to` the tenths of-'a degree within each degree, if -it is to be d-onefi-neach instance.-v instantaneously, a channel can,able providing; for the transmission of thirty'diifferent sets/, of; impulses mustbe provided The live-conductor channel comprising'Y conductor-sf 2v2-esto; Zit; inf` clusive, can transmitY instantaneeuslyyanyi one of 2.5 or thirty-two different sets impulses to Daly: thirty ofrthese.vv

define thirty-two numbers. willV be employed, however. Twenty of theseF sets of i impulses: willfdefrne twenty equal 'steps in theV rotation ofv `cam-s 2H to 21e; inclusive; through each 20.-degree zone. Tenof thefcharacters will dene ten equal divisions in one rota'- tion ofvernier crankshaft 252. Crankl 2-2wi-neohe complete rotation turns telescope't through- "one degree. Theten divisions areequal,A eachde` y sixteen numbers cr characters.

lining atenth ofa degree.

A separate channel isvclevotedtor the transmissionof impulses defining the tenons-hundredths of. a .degree in each tenthof adeg-ree; TheY channel comprisesfour conductorsf'Z-iiito` 2319; inclusive. By means` of the four? conductors,, it,r would be; possible to transmit instantaneously any of sixteen different sets-'o'impulses defining- OnlyY teni of these are requiredtotransmit impuisegdening ten=different hundredths offadegree.A Ascranlt-v sh'ait 2&3#h rotates through cnet-tenth. cii a.rev.olu-.V tion, ten different setsi of impulses, eachden:=

' ing a diierent'hundredth ofc-a `degreaare transf The ratio mitted over conductorsl 236 to 239, inclusive, through the operation of cams-23| to 234, inclusive, each of which actuates its individual follower to close an individual contact to ground in accordance with the assigned code.

Attention is particularly called to the fact that one complete revolution of Vernier crank 202 I'otates telescope 20| through one degree. It would appear desirable, therefore, in coupling a shaft through gearing to the Vernier shaft for controlling the transmission of impulses to dene each of ten-hundredths of a degree to provide gearing having a ratio of ten to one so that the hundredths of a degree shaft would make ten revolutions for each revolution of the Vernier shaft. For reasons which will be made apparent below, the shaft on which the hundredths of degree cams are mounted is coupled to the vernier shaft through gearing having a ratio of but five to one so that the hundredths of a degree shaft revolves but five instead of ten times for each revolution of the Vernier shaft. For each revolution of the hundredths of a degree shaft, therefore, the vernier shaft rotates through twenty one-hundredths of a degree. During this interval, twenty sets of impulses, each defining a different one-hundredth of a degree, are transmitted over conductors 236 to 239, inclusive. While the hundredths of a degree shaft 240 rotates through the first half of a revolution, which corresponds to ten one-hundredths of a degree, ten different sets of impulses, each defining ten different one-hundredths of a degree, are transmitted over conductors 236 to 239, inclusive. While shaft 243 turns through the second half of a single rotation, ten more sets of impulses each defining ten different hundredths o-f a degree are transmitted, making a total of twentyhundredths of a degree. Each of cams 23| to 234 is divided into twenty equal segments. Each segment will either raise its respective cam follower to close its contact or permit it to remain in the lowered position. By means of the four conductors 233 to 239 and the four sets of cams 23| to 234 it would be possible to transmit instantaneously any one of 24 or sixteen combinations of signal impulses resulting from the open or closed conditions of each of the four contacts. It is necessary to make use of only ten of these sixteen possible combinations to define each of ten-hundredths of a degree. As shaft 240 turns through the rst half of each revolution its fo-ur cams 23| to 234 set up ten different combinations of closed and open contacts to dene ten different hundredths of a degree as rvr indicated in the code chart per Fig. 4 in the vtop ten lines of the box. As indicated in the first line for the first position, all contacts are open since none of the four rectangles in the first line is cross-hatched. For the second position, when shaft 240 has turned through one-twentieth of a revolution contact 242 closes. When shaft 240 turns through another twentieth revolution, contact 243 also closes. As shaft 240 turns through each successive twentieth of a revolution, contacts 24| to 244 close or open as indicated in Fig. 4. It is particularly pointed out that only ten distinctive code combinations are employed. Each of the ten combinations which is` employed is used twice to define each of twenty-hundredths of a degree. It is further pointed out that when the combinations are repeated they are repeated in reverse order. That is to say, the cam cuttings in the eleventh position instead of being the same as in the first position are the Transmission of hundredths of a degree informtion The manner in which the hundredths of a degree information is transmitted from the observing station to the central station will first be described.

When cam 23| raises its follower, a circuit is closed from groundthrough contact 24|, conductor 23E and the winding of relay 30| to battery operating the relay 30| to engage its M contact. When cam 232 raises its follower a circuit is closed from ground through contact 242, conductor 231 and the winding of relay 332 to battery, i

operating the armature of relay 302 to engage its M contact. The winding of relay 30B is connectf ed in parallel with the Winding of relay 302. Its operation will be described below. When cam 233 raises its follower a circuit is established from ground through contact 243, conductor 238, winding of relay 303 and the left-hand winding of relay 305 to battery, operating the armature of relays 303 and 305 to engage their respective M zontacts. Relay 305 is not directly involved in the transmission of hundredths of a degree information and its function will be described more fully later. When cam 234 raises its follower, a circuit is established from ground through contact 244, conductor 239 and the winding of relay 304 to battery, operating the armature of relay 334 to engage its M-contact. A parallel circuit is also established extending through the winding of relay 301 to the S contact of relay` 308, the function of which will be explained below.

Relays 30|, 302, 303 and 304 control the selective connection of battery 309 through a fan circuit extending through the armatures and contacts of relays 30|, 302, 303 and 304 to ten conductors, numbered 3|| to 320, inclusive. Each of conductors 3|| to 320 has ten parallel branches, each extending to the top terminal of a lamp. The lamps are arranged in ten banks of ten. Each of the ten conductors has one branch extending into one lamp in each group of ten lamps. As thus arranged, as cams 23| to 234 actuate their followers in accordance with the ten codes in the top ten lines of Fig. 4, relays 30| to 304 will be operated or released correspondingly to connect battery 309 in turn to the ten different conductors 3|| to 320 and through each of the ten different conductors simultaneously to the top terminal of each of ten lamps connected inv parallel to each conductor. One lamp in each bank of ten lamps will thus have battery connected to its top terminal for each of the ten codes during the first half revolution of shaft 240, The same lamp in each bank of ten lamps will also have battery connected to its top terminal as shaft 240 turns through the second half of its revolution and actuates cams 24| to 244 in accordance with the same code in reverse order. It is particularly pointed out that batteryy is supplied to the top terminals of each of the hundred lamps twice during one complete revolution of shaft y240 and that if a steady ground were connected to the opposite terminal of each lamp, one lamp in each 'bank of ten would light simultaneously. Ten

Vone lamp at a lamps, one in` each bank ofV ten, would first light. Then as they code changed ten other lamps, one in each. bank of ten, would light until each of theten lamps in each group of ten had lighted as shaft 249 rotated `through one-half revolution. Then .the operation would be repeated, so that-if a direct. ground were connected to the bottom terminals of all of the hundredths of a degree lamps,.there would be two hundred lamp lighting operations as Yshaft 2.4tlturned through one revolution representing twenty-hundredths of a deg-ree. Only twenty lamps are in fact lighted,

time, to define twenty one-hundredths of a degree change for each revolution of shaft 246, This is performed by connecting ground selectively to theY proper group of tens lamps in each bank, under control of cams 22| to 224', which define the Ytenths of a degree. The manner in which this is performed will be explained below. Y Y

The chain circuits through the contacts of re- 1lay 39| to 304 corresponding to various codes per Fig. 4 will now be traced. It is assumed that the armature of relays 39| to 394 are actuated to their respective M contacts when -cam vcontacts 24| to 244 are closed andthat the contacts are closed by raised surfaces on cams 23| to 234 inthe cross-V hatched positionsin Fig. 4. It is assumed that the armatures of relays 30| to 304 are open and thatl the contacts are openY by depressed surfaces on cams 23| to 234 where'positions are not crosshatched in Fig. 4.

In Fig. 4 four vertical rows from left to right represent the condition of cam contacts 24| to 244, respectively, whether open or closed. There are twenty horizontal rows in Fig. 4 corresponding to the twenty equal segments into which the peripheries of cams stead ofbeingnumbered from to 9 and then repeatingfrom 0 to 9 the horizontal rows are numbered 5, 6, 7, 8, 9, 0, l, 2, 3, 4,

5: .6: 7: 8: 9: 0s l, 2, 3, 4. The reason for this, as will become more apparent below, is thatthe code for the degrees, controlled by contacts 2|6 to 22D is transmitted ,from the observation station'during the interval while the hundredths cams are in the zero region and' it lessens the danger of interference if no changes in the ground connections, to the ten banks of ten lamps, underl control of camsv 22| to 224 are made in the zero region. Therefore the hundred lamps are separated into groups of ten, as indicated in Fig. 3, between 04 and 05, 14 and l5, etc., to 94 and 95.

As indicated in Fig. 3', the rst groupof ten lampsy are numbered from 95"to 04. It will be shown that ground is connected to this bank of ten lamps when cams 22| to 224 are in the position indicated in Fig. 2. Y That is to say, when the contacts associated with cams 22| to 224 are all open, the tenth degreerelays 32| to 324 controlled by these cams are in such condition that ground is connected to lamp bank numbered 95 to 04. Therefore during the first half ofthe first revolution of shaft 24|), ground is connected to lamp banky 95 to04. During the second half of the revolution of' cam shaft 249, ground will be connected to thebank of lamps numbered 05 to 14. Duringthe rst half of the second revolution of Lshaft' 240 ground will be connected to lamps 15 to 24. During the second half of the second revolution, ground will be connected to lamps 25 to 34, etc. Relays`32| toY 3,25 will be operated under control of cams 22| to 224 in accordance with the code indicated in Fig. 5 to effect these changes. At theleft of iFilg". 41 therefore the numbers 95.-()4' 23| to 234 are divided. In-

ten lines indicate that lamps so numbered areV also so controlled. Numbers 05-l4, 25-34, Ll5-.54, 65,-'74 and 85-94 opposite the bottom ten horizontallnes in Fig. 4 indicate that lamps so numberedare controlled by. cam cuttings arranged inV accordance with the pattern in the second ten positions on cams 23| to 234.

Refer now to the code indicated by the top line of Fig. 4. No raised surfaces are indicated for any cam. Relays 39| to 394 are all released. For this condition all of their armatures engage their respective S contacts. A circuit may therefore be traced from battery 339 through the S contact of relay 2h34, S contact of Arelay 393, VIS contact ofrelay 332 and 3S contact of relay 30|V to conductor 3i@ which connects to lamp 95.V

The'next code requires the operation of relay 392' andi the release of 39|, 3.33 and 394. The circuitinay be traced from battery 399 through the S contact of relay 394, S contactof relay 303, IM Contact. of relay 392 and the 2S contact of relay 33t to conductor'lt. This connects to lamp 96.

The code shown in the third line of Fig. 4 calls for the operation of relays SSZ'and 303 and the release of relays 39| and 394. VA circuit may be traced from battery 339 through the S contact of' relay 394, M contact of relay 333, and the IS contact of relay 39! to conductor 3|2 which connects to lamp 97. If the circuits corresponding t0 the remainder of the codes indicated in the next seven lines in sequence are traced they will be seen to connect battery 399 to the top terminalof lamps 9S to 04 in sequence.

During the interval while shaft 249 is rotating through the rst half of its first revolution it will be shown below that a common ground is connected, as a result of the operation ofthe tenth degree cams, to lamp bank to 04 in parallel, so that each of these lamps lights in sequence,

iter conipieting the first half of the rst revolution, when shaft 249 rotates into the eleventh position of its twenty positions for the rst cam Vsettingfor the second half of its rotation, refer- 24| only is closed. The other contacts are open. Y

Relay 39| only is orated in the tenth position. Thecircuit for this conditionV may be traced from battery 399 through cont-act S of relay 304, contact S of relay 393, contact ViS of relay 392 and contact 3M of relay 39| to conductor 355. Conductor 3|5 connects to lamp-04 in the first bank of ten lamps. The setting of the hundredth degree cams, as indicated in Fig. 4, does not change between the tenth and eleventh position of the twenty positions on cams 23| to 234. Battery will therefore remain connected toY conductor 3|5 for each transition between the tenth and eleventh settings of the camsas the cam settings are the saine and do not change in any way. As aresult of this, it is necessary to change the ground connections only on changes from 04 to 05, 14 to l5,

24 t0 25, 34. t0 35, 44 t0 45, 54 t0 55, 64 to 65, "I4

four of relays to 304 be released. If the path for this condition is traced it may be seen to extend from battery 309 through contact 304s, contact 303S, contact IS of relay 302 and contact 3S of relay 30| to conductor 3|6. The top line in Fig. 4 shows that the code for lamps 15, 35, 55, 75 and 95 and therefore the setting of the relays and the connection of battery to the conductor is the same as that for lamps 14, 34, 54, 74 and 94. Conductor 3I5 is shown connected to lamps 14 and 15, 34 and 35, 54 and 55, 74 and 75, and 94 and 95. Reference to Fig. 3 shows that lamps 14, 34, 54, 74 and 94 are each the last lamps in various banks of ten, while lamps l5, 35, 55, 75 and 95 are each the first lamps in corresponding succeeding banks of ten. No change therefore is required in the settings of the relays and in the chain circuits from battery to the top terminal of each of these lamps for transitions between them. The transition requires a change in the ground connection only between the common conductors connected in multiple to the bottom terminals of the particular groups of ten lamps affected by the transition.

Operation of circuit for indicating transition between tenths of a degree Transitions between tenths of a degree effect changes in the settings of contacts individual to cams 22| to 224 in accordance with Fig. 5. The table at the left of Fig. 4 indicates the tenth degree zones deiined by cam settings in the corresponding ten lines of Fig. 5. Instead ofrdividing the tenth degree zones between 99 and 100,9 and 10, etc. the zones are divided between 94 and 95, 04 and 05, etc. as indicated in the table to correspond with the lamp groupings described above.

As cam contacts 22| to 224 are closed and opened, in accordance with the codes per Fig. 5, relays 32| to 325 are operated and released from ground through the cam contacts, conductors 228 to 229, respectively and the windings of the relays 32| to 325 to battery.

Attention is called to the fact that conductors 226 to 229 are only four conducting elements of a channel consisting of five conducting elements. The fth conducting element, conductor 230, is

not employed in transmitting any of the codes y for the tenths of a degree. Reference to the right-hand Vertical column in Fig. 5 discloses that the fifth conductor, conductor 230, remains in the open condition for each of the codes assigned to the tenths of a degree. Codes requiring the closing of conductor 230 are assigned only to degrees. This may be seen in the right-'hand vertical column of Fig. 6. Y

A number of the circuits established by the operation of the tenth degree cams will now be traced.

The top line in Fig. 5 indicates that all of cam contacts 22| to 224 are open for the tenth degree zone starting at each ninety-fifth hundredth of a degree and ending at each fourth hundredths of a degree or 95-04 as indicated in Fig. 5. When- ,ever tenth of a degree codes are transmitted conductor 230 is open as indicated in the right-hand column of Fig. 5. Why it is open will become more apparent below. For this condition therefore relays 32| to 325 are released. When all of these relays are released, the' path leading from the parallel branches connected to the M contact of relay 305 and the S contact of relay 306 and extending throughcontact 325s; contact 324S, contact IS of relay 323 andgcontact 2S of relay 322 is open at the 4S contact of relay 32|. So

no matter what the condition of relay 305 or 306,

relay 308 will be released for this condition. Reference to relay 308 shows that battery is permanently connected to the left-hand terminal of its winding. To operate the relay ground must be supplied through the chain circuit to the righthand terminal of the winding. When relay 308 is released, ground is supplied through its upper armature and S contact through conductor 340 to lamps -04 in parallel.

While ground is connected in paralle1 to lamps 95-04, each of these lamps will be lighted in sequence as the Vernier is turned through correspending positions for each degree.

Reference t'o the second lineV of Fig. 5 shows that for the second tenth-degree Zone, that is, for the ten of a degree beginning at live-hundredths of a degree and ending at fourteen-hundredths of a degree, or 05-14, cam 22| operates relay 32|. Relays 322, 323, 324 and 325 are released. Relay 306 is released during the transition from 04 to 05 because, as shown in lines 10 and 11 of Fig. 4 the periphery of cam 232 is depressed during this interval.l Therefore ground is connected through `the S contact of relay 306, S contact of relay 325,

S contact of relay 324, IS contact of relay 323, 2S contact of relay 322 and the 4M contact of relay 32I, which is the only operated relay in the chain, to aparallel circuit. One branch of the parallel circuit is connected in parallel through conductor 34| to the bottom terminals of lamps 05-14. The other branch is connected through resistance 33| and the-winding of relay 308 to battery, operating relay 308. When battery is connected to the bottom terminal of lamps 0.5-14 each of these lamps is lighted in sequence as the Vernier rotates through corresponding positions. The operation of relay 308 disconnects ground from its top S contact and conductor 340 which prevents the lighting of any of lamps 95-04 while the Vernier is rotating from O5-14. vThe operation of relay 308 also established a circuit from battery through bottom contact 308M, right-hand winding of relay 305 and the right-hand winding of relay 3|0, operating the armatures oi relays 305 and 3I0 to engage their respective M contacts.

It is particularly pointed out that relay 308 is released only during the interval While the Vernier is in the region between 95 and 04. For each other tenths degree combination relay-308 is operated from ground supplied from relay 305A or 306 through an individual path through the fan circuit extending through the contacts of relays 32| to 325, inclusive and some one of the resistances 33| to 339, inclusive to the right-hand terminal'of relay 30S. A corresponding bank of tenr lamps will be lighted through some one of conductors 34| to 340. For instance, for the tenth degree zone beginning at 15 hundredths and ending at 24 hundredths in each degree as indicated in Fig. 5, the contacts of camsl 22| and 222 will be closed and the contactsY of cams 223, 224 will be open. A circuit may therefore be tracedl from ground through contact 305M, contact 325s, contact 324s, contact IS of relay 323, contact 2M of relay 322 and contact 3M of relay 32| which connects in parallel through resistance 332 to the right-hand terminal of relay 4308 and through conductor 342 to lamp banks 15 to 24. For the tenth -degree Zone beginning at Vernier position 25 and ending at Verniereposition 34, as'indicated in line 4 of Fig. 4, relay 322 is the only chain relay operated. The circuit will therefore extend from ground through contact 305M, contact 325s,

contact 324S, contact IS ofrelay 323,:V conannessi tact 2M of relay 322Y and contact 3S of relay 32E to resistance 333 and conductor 343 in parallel Relay '358 remains operated and the bottom terminals `of lamps in 'the bank 25-34 are supplied with ground. For Vernier positions 3544, 45-54, 55-64, 65-74, 'T5-84 and 85-94, if relays 32|-25 Vare assumed to be operated Where a position in a corresponding line in Fig. 5 is cross-hatched and i released where a position is blank, circuits may be traced from ground through contact 355Mr and through an individual paththrough .contacts of relays 32| to 325 for each relay group setting indicated by the particular line in Fig. 5 to a single group often llamps correspondingly numbered. Relay 308 Vwill be maintained operated simultaneously from ground supplied through resistances 333 to 339.

`Only one bank often lamps will have battery supplied `to its bottom terminals at any one time.V Relay 338 is released only Vwhile the Vernier is in the teeth of a degree position between 95 hundredths and 04 hundredths. Therefore ground will be supplied to lamp bank 95-04 only during this interval. During the interval while relay 398 is operated while the Vernier is in the other 90 hundredths of a degree positions, ground can be connected to only one bank of ten lamps for each of the settings indicated in the nine bottom groups of codes of lFig.'5. Reference to the various possible circuts throughrelays 32| to 325 will disclose that' it is not possible to establish more than one closed path through their contacts simultaneously for any of the operate and'release conditions of relays 32| and 325'indicated in any of the eode'condtions of Fig. 5. 1 Y The cooperationA of the apparatus governing the selection of each of the lamps by the hundredths of a degree mechanism and vthe tenth of a degree mechanism therefore will result in the lighting of one lamp only for each one-hundredth setting of the Vernier. Y

Transmission of degree information The manner in which the mechanism functions to transmit degree information, will now be de- Y scribed. i l

It has been explained that as shaft V2138 revolves through twenty degrees about Vspindle 206, it

rotates once von'its own aXis, turning each of Ytransmit both tenths of a degree informationV as switch 245. In ther two Vernier positions in which well as degree information, provision is made, in Y an important feature of this invention, to prevent interference in operation between the mechanism employed to transmit and record this information. A separate set of recording relays 326 to 330 isprovided to record the degree information. Conductors 223 to 230 inclusiveare Y extended through the bottom windings of relays 325 to 339, respectively. Relays 325 to 333 rei but in no case is a circuit continuous from ground through the contacts'of relays 32! to 325 toany 308, which relay remains released. v No Llamp- 'in any bank can therefore be aiiected by the'transmission of the degree information.

In the description above it was explained that all ofthe contacts of cams 221 to 22d are open when the code for the tenths of a degree zone, starting at hundredths and ending at 04 hundredths', is transmitted. This is indicated in the top line of Fig. 5. It was also explained that during this interval relay 333 remained released and that ground was supplied to the bottom terminal of lamps 95 to 04 through the top S contact oiV relay .338 instead of from the M contact of relay 335 or the S contact of relay 395. It is not nec essary therefore to supply ground from relays 335 or 355 to any of the lamps orto the right-hand terminal of relay 338 for the tenths zone beginning at 95 and ending at 04. The ground from relays 395 andr355 is therefore disconnected from the chain circuit for anumber of theV positions of the Vernier in the Zero hundredths regionrwhile the degree f code information is transmitted. Therefore, ino matter whether or notV relays 326 to 325 are operated or released in response to the degree'codes, the lamp banks corresponding to the hundredths of a degree are not aifected in any way. Y Y Y Normally switch '245 is open. VSwitch. 245 has ve separate contacts. It is under control of cam 225, mounted onV Vernier shaft 1292. Cam 225 operates switch 245 to close the 'five .circuits fromY cam contacts 2l5 te 223 through the rive armatures of switch 245, conductors 22S-to 239 and the windings of relays 325 to 330 `and 3,2! to 325 in 'parallel to battery,iwhile the Vernier is in position 96.5 to 03.5. Only during this interval corresponding to seven' one-hundredths of a degree can degree ycodes be transmitted.V The `degree' cams actually set vtheir respective contacts, which thereafter remain set for each degreelcode, while the Vernier is moving between 45 and 50. This is Y approximately one-half vdegree in advance of the position of the Vernier at which the codes setup during the-45 to 50 interval are actually transmitted. The reason for this is toV insure that the degree cams contacts are actually at rest in their proper positions when they are connected to their respective conductors 22B to 239, to reduce the i possibility'for mutilation due to possible bouncing of the contacts, etc., when closed or opened, if they 'were closed and opened at about the time that they ywere vconnected to their conductors.

There is another protective feature in the invention designed vto guard against mutilation dur-i ing the closing and opening of the contacts of the position of switch 245 actually changes the positions of its ve contacts, namely at 96 and 03, whether to open or close the switch, depending upon the ldirection of rotation of the Vernier on either increasingA or decreasing azimuth, ground is ydisconnected from thefan circuit through relays 32| to 325 to the hundredths lamps. Reference to the second line from the top in Fig. 4 shows that at position'96 of the Vernier, contact 242 only is voperated. by hundredths of a degree cam 232. This connects ground through conduc tor 231 to thetop terminal of relayt. Since relay 393 isreleased for Vthe 95 tolle tenths of a degree zone, battery is connected fromY bottom contact '3988 tothe bottom terminalof relay 395 roperating relay 335 in this position. The armaturev of relay 355 is in engagement with its M con- Y tact so that no ground islconnect'ed through theV of the banksof lamps orto the Ywinding of--relay 1'IIS fan circuit of relays 324 to 325 froinrelay 306 for this condition.' Both windings of relay 305 are deenergized for this condition because battery is disconnected from the bottom M contact of relay 308 so that the right-hand winding of relay 305 is deenergized andicontact 243 is open so that the left-hand winding of.relay305 is deenergized, The armature of relay 305 is on its S contact. No ground therefore can be connected to the fan circuit through relays 32| to 325 from relay 305 either. So ground is disconnected from the fan circuit through relays 32! to 325 for position 96 in each degree.

Reference to the ninth line from the topin Fig. ll for the 03 position of the Vernier indicates that the positions of cams 232 and 233 is unchanged from that for Vernier position 95 described above. Relays 395 and 306 are in the same condition as described above and ground is disconnected from the fan circuit for this position also. As a result of this even though a perfect simultaneous closing or opening of all of the contacts of switch 245 in Vernier positions 96 and 03 is not effected, the banksoi the hundredth degree lamps will be unaffected as no ground, is connected through the fan circuit of relays 32'! to 325 for either of these Vernier positions. The contacts will assume a proper final position, however, whether open or closed before the Vernier' I has moved into the succeeding position.

To return now to a consideration of the operation of relays 326 to 330 which record the degree settings, these relays are normally in positions corresponding to the code last recorded by them. Relays which have been last operated by the code are locked operated. Relays 326 to 330 are neutral relays. Relay 3|0 functions to unlock those of them which have been locked in the operated position by the impulses of the previous code and to connect them to conductors 226 to 230 only while the Vernier is in a few positions in the zero region. This will be fully explained below. The relays are set in accordance with the code for the new degree cam setting. Then relays 326 to 330 are disconnected from conductors 226 to 239 so that their settings will not be mutilated by the codes for tenths of a degree. Since relays 326 to 330 are neutral relays those of them which have been operated by the particular degree code must be locked in the operated position between the re ception of degree codes. This is eiected by a locking circuit through each of their top windings under control of relay 3H).

It was shown above that relay 308 is operated for ninety of the one hundred Vernier positions namely from positions 05 to 94. During this interval, as explained above, the armature of `relay 308 remains in engagement with its M contact which establishes a circuit heretofore traced from battery through contact 308M and the right-hand windings of relays 30E-and 3|0. Relay 310 remains operated over this path and its armature therefore remains in engagement with its M contact while the Vernier is in any of the ninety positions from 05 to 94. As may be observed, there is a second winding on relay 310. The lefthand winding is under control of relay 301. The left-hand winding of relay 3|'0 is energized while relay 301 is released. Relay 301 is under dual control. I In order to energize relay 301, relay 308 must be released to connect battery to the bottom terminal of relay 301 and cam 234 must close contact 244 to connect groundto the top terminal of relay 301. Battery is connected to the bottom terminal of relay 301l as has been shown, while the Vernier is in the ten positions from 95 to 04 established through the contacts of relays 326 to fcondition to respond to degree codes therefore only while the Vernier is i-n positions 98, 99, 00 and 01. During the other ninety-six positions of the `Vernier relay 301 is released and ground is 'connected through contact 3015 and the left-hand fwinding of relay 310 operating relay 3I0. The

operation of relay 3 I 0 for the ninety-six positions of the Vernier from 02 to 97 opens the operating paths through each of relays 326 to 330. The operation of relay 3I0 also locks those of relays 326 to 330 which have been operated by the code impulses.

Relays 326 to 330 are operated or released in accordance with the degree codes. The top armature of any of these relays Which is operated is actuated to engage its M contact. Relay 310 is fast in operating and operates before any one of relays 326 to 330 which has been operated can released. This established a locking path from battery through contact 3l0M top windings of relays 326 to 330, armatures of relays 326 to 330 and to ground through the top M contact of any relay which has been operated, locking each operated relay.' Relays which are not operated in accordance with the received code, of course, re-

main in their normal released positions. The paths from the degree cam contacts to conductors 226 to 230 remain open, due to the operation of cam 225 and the opening of switch 245, until the .change in setting of the azimuth requires a change in setting of the degree relays. Relay 3 I0 remains operated during this interval and the settings of relays 326 to 330 remain unchanged.

If the telescope 20| were not required to be rotated in more than one direction, such as clockwise, it would be necessary to provide only twenty individual degree lamp selecting circuits, one for each of the twenty degree lamps. One such selecting circuit would be established by the operation and release of relays 326 to 330 for each of the twenty codes indicated in Fig. 6. The telescope 20| must be rotatable in either the clockwise or counter-clockwise direction, however, to follow a target the movement of which is unrestricted.

Let it be assumed that the position of the telescope is in the neighborhood of 18.25 degrees and that the azimuth is increasing. As the Vernier passes through 18.45 degrees to 18.50 degrees a new code is set up by cams 2l l to 2 I5. The code will be stored on the contacts and will not be transmitted to relays 326 to 330 for recording until the Vernier is inposition 18.98 degrees. Let it be assumed that, in response to these, the 19#- degree lamp is lighted when the Vernier crosses 19.00 degrees. If the azimuth continues to increase there is no difculty. Suppose, however, that the telescope must be rotated in the opposite direction back into the 18-degree zone. Since the cam settings for the degree codewill not again change until the azimuth is in the 18.50 degree to 18.45 degree zone, some provision must be made to record the change back into the l'-degree zone. In order to do this two selecting circuits are 330 for each of the twenty diiferent degree codes shown in Fig. 6.: Relays 326 to 330 are each equipped with forty sets of bottomV contacts. Only three sets are actually shown. Two'identi- .each degree.

Lcalchain circuits areles'tabli'shedthrough the Vconta'ctsof relays toj 330 'for each of the twenty .di'erent codes There .iis 'one chain Acircuitv for increasingland another for decreasing .yer-.nier for .Each-'such pair .of fch'ain circuitsis v-conn'ectable through a lamp tobattery. There '.isibutone lampi foreach degree camsetting. The

' opposite endsloiieach.fchainercuit is connectable V:toig'round .through the 'opposed contacts :and armatures Vof 4polar relay .350. The polar relay :fis .controlledeby thezhundredthsdegree.cams iir'such V.manner that whentheivernierlpass'es throug'hipo- :chainfcircuits controlled .by the code fornineteen degrees butidesignated 118-'deg'r'ee retrogre's's lamp 'be Yenergized to 'light :lamp 18. The manner in-Whichtheftwentypairs of .chain .circuits correspondingto' Atwenty codes such'as indicatedzin Fig.. '6 Vmay be established through forty sets ici contaet's of vthe ve relays 326 to 33!) shouldf'lo'e obvious from lreference 'to the three chain circuits which are shown by way of examm ple. The '.circuitfor 19^degree .advance may be traced frornoattery "throughfth'e larnent of the .l-:degree 'advance .lamp through the :front contact of relay 2330 fand through the break Vcontacts of relays 3219, 328, 321 land 3291in sequence; the settings -o-f all of which relays c'orlrespc'md to 'the `ciode lfor .nineteen Vshown iin the bottom line of flig. 6.,'.to Ythe M.contaot of relay 2350. 'The circuit for 'the 1d-degree retrogress lamp 'may be traced from 'battery .through the filament of the 18de .greerretrogress lamp through .the `front `Contact oi relay330 and through the back contacts of re- 'lays;32'9, :328,f321fand 329 to the S Contact vof re- Y lay 350. Attention is .called Vto the fact that 'the position vo1" the yrelay contacts in :the chain circufits through Arelays 3.2.6 to Siris the same `for :both 'of these lamps. Both'o'f these rchaincircuits were established by the same setting of the degree cams, namely the cam `settings "established when the azimuthpassed betwe'ffen 18.45 degrees to"1r-8;50 degrees and bdthcorr'espond to the Ysetting lindicatedrl in the -bottoin Vli'rie "of Fig. i3.

gress is lighted will depend upon the direction of -theimoyement foi the Vernier and the operation of the :hundredths .of ia 'de'gree'cams in response thereto. This will now be'exrfila'ined in detail.

Relay 350 is under contri of relays 301 'and totbattery through -thet'op Winding of relay 350,

or through contact '5S of 'relay 3701, when relay 3G! is released, toY battery through the bottom :winding of .relayf35- The position of relay 39| while the'vernier is lin V1cosit'ions98', 99, 00 'and 0l determines which .of'zthe 4windings of relay 350 is energized'by the ground from relay 301. YThis in turn'deterrnines in 'which d-recton'the armature Y of A*relay 359 willbe .actuated and Y'which of the twolam'prcirciiits' set upby such degree code will be "closed,

:emessa 16 Y Relay 350 isproVided-with two locking circuits. One extends from battery through the topwinding .of relay 359, through resistance 35| kvtotheM contact of relay 350. The other extends from .battery through the Vbottom winding of relay 35|', through resistance "35.2 to the S yContact of relay 359. When the armature 'of'relay "359 is fon its M contact. current suicient to hold the .armature in engagement with the M contact oWs through the top winding provided full current does not flow through the bottom Winding. Whenthe armature of relay '350 'is on its S contact, current suflicient to holdthe armature in engagement with its S Contact vflows 'through 'the bottom winding provided full'current doesfn'ot flow through the `top winding. VIn ninety-six of the hundred Vernier positions in each degree the armature oi relay 35i! will be held in engagement. Y

with either its S or its .M contact .by either ofit's locking windings. The contact on which 'the :ar-

mature is held is the contact toV which it waslasty actuated by relay 39! 'while the Vernier was in y'the four Vernier positions 98, 99, 100 aiihd 01 and .ground was supplied from the M contact :of relay 301.

'Let it be assumed that the armature of relay 350 is in engagement with its M contact and that Yit is locked to its M'contact by current ilowing from battery through the top Vwinding of 'relay relay 350 through 'itsV armature rto ground. "'Let it be assumed that telescope 20! is in position 18.30 degrees and that the azimuth lis increasing.V

When the Vernier moves l'i'.l-irou'gh positions '1T845 degrees to 18.50 degrees thefl'Q code Willi'be'set up on contacts Zi to 220'by cams` 21C! to 215. Switch 295 is open 'so the degreecode is nottransmtted at this time. YThe code for 'the tenths and hundredths of Va degree are trfansmitted'continuo'usly by the action of 'cams-22|' to 224 and 2.3i to 234. W'hen the Vernier reaches position 18.95 degrees relay '398 releases. the yernier reaches 18.965 degrees switch 2545 closes. When the Vernier reaches 18.98 degrees relay 39'! operates. Relay 3 l0 which hasbeen locked vre leased. T,The particular relays ot the degreeV coding relays 326 to 3-30 which were operated in response to the last code signals which were `re ceiv'ed will be unlocked. The code'for thenin'eteen position vwill beV impressed on relays '325 to 330. In response to this they will establish two circuits as has been elola'ined from battery tllnugh the 19 Vadvance lamp and from "battery thro gh the 1 `8 retrofgressV lamp, throl'igh two in'i dual chain circuits extending through Vthe arxr'i'atu-resof relays 325" to 338', to the larmature "of l350. When relay '39"' Opfer-ttes at 18.793 ide rees 'it conlrrects ground kto its 'M contact. As 'ndic'at'ed lin the i'lrst column of Fig. "4 during this interval relay 39! is in the released condi-V Y sixth ence groeperen@ refr-'ilaria temine office.

4 Vrelay sa: remains oper-atea arida-'relay .3a-i f epee at'es. This establishes a lcircuit from ground through remy Contact scrivi, thelist/i cent-act Ver relay 305| and the top Winding O lrly 350 to This condition will obtain Y.

teryfv The armature of relay 350 will be actuated to its M contact. This will close the circuit of the 19 advance lamp and it will light. Vernier continues to increase there is no change in the condition of relays 301 or 30| until, as indicated in the right-hand Vertical colinnn in the eighth code group from the top for the 19.93 degree position of the Vernier relay 301 releases. This disconnects direct ground from the top winding of relay 350. But the armature of relay 350 is locked to its M contact by its locking path. The release of relay 301 operated relay 3|0. This disconnects relays 325 to 339 from conductors 225 to 230. Relay 3|0 also locks those of relays 325 which are operated by the 19 code. Those relays of relays 325 to 330 which have remained unoperated by the Y19 code maintain their released positions, of course, without locking. When the Vernier reaches positions 19.035 degrees, switch 245 opens. When Vernier position 19.05 degrees is reached relay 308 operates supplying an additional locking path for relay 3 0 and preventing the reep-eration of relay 351 on Vernier settings other han 98 to 02. The circuit for the v|9 lamp is therefore locked and the 19 lamp remains lighted.

Let it be assumed that the azimuth continues to increase for a time while cams 22| to 224 and 23| to 234 control the hundredths of a degree lamps to correspond. Let it be assumed that the azimuth passes through 19.45 degrees to 19.50 degrees and to 19.60 degrees. As the azimuth passed through 19,45 degrees to 19.50 degrees the 20 code shown as the zero code in Fig. 6 would be set up on contacts 2|@ to 220 by cams 2!! to 255.

Let it be assumed that starting at 19.50 degrees the Vernier is turned backwards. The 20 code would not be transmitted because, as has been shown. the Vernier would have to be rotated to 19.965 degrees before switch 245 is even closed. As the Vernier is rotated so a-s to lower its reading when the Vernier passes through 19.50 degrees to 19.45 degrees, the 2O code would be wiped out and the 19 code would be reestablished. When the Vernier position 19.04 degrees is reached relay 300 again releases unlocking the right-hand locking path of relay 310. When Vernier position 19.035 degrees is reached switch 245 recloses. Relay 30|, as indicated in the left-hand column of Fig. 4, is operated at this time but it is ineffectual because relay 301 is released, as shown in the right-hand column of Fig. 4. At Vernier posi.- tion 19.01 degrees relay 301 reoperates. This un locks the left-hand winding of relay 3 9 which releases its armature to S in turn unlocking relays 326 to 330. The code for I9 is impressed on relays 325 to 339. This will involve no change in the settings of the relays as the code is the same as last sent. With the armatures of both relays 30| and 391 operated to engage their M contacts a circuit is established through the top Winding of relay 359. This continues to hold the armature of relay 350 on M momentarily. At position 99 of the Vernier, corresponding to position 18.99 degrees, as shown in the iifth code group from the top in the left-hand column of Fig. 4, relay 30| releases. Relay 301 remains operated as indicated in the fifth code group from the top of the right-hand column of Fig. 4. This establishes a circuit through the bottom winding of relay 350. Full current flows through the bottom winding, preponderating over the holding current in the top winding of relay 350 and the armature of relay 350 is actuated to engage its S contact. This closes the circuit through the 18 lamp. Relay As the 30| remains released and at 18.97 degrees relay 301 releases. This disconnects direct ground from the bottom winding of relay 359 butthe armature of relay 350 is maintained on its S contact by its holding circuit. The release Y oi relay 301 at Vernier position 97 reoperates relay 3|0. This again disconnects relays 325 to 330 from conductors 226 to2-39 and reestablishes the locking path for those of the relays which have been operated by the degree code. "At 96.5 switch 245 again reopens. At 95 relay 308 again releases.- The circuit forthe 18 lamp is locked lighted until the next cycle.

What is claimedis: v

1. In a -data transmission system, an observing station, a receiving station, means at said observing station -for making measurements, means at said observing station for translating said measurements into a fourdigit number, means at said observing station for translating each of the` ten possible numerals in the units'place in said number into a particular one of ten of sixteen possible code combinations of electrical impulses in accordance with a four-element permutation code, means at `said observing station for impressing said combination of impulses simultaneously on four conductors comprising a rst channel interconnecting said stations, means at said observing station for translating each of the ten possible numerals in the tens place in said numf ber into-a particular one of ten of'thirty-two possible code combinations of electrical impulses in accordance with a iive-element'permutation code, means at said observing station for impressing said electrical impulses, deining the numeral in the tens positions, simultaneously, at a rst time, on four of iive other conducting elements comprising a second channel interconnecting said stations, means at said observing station for translating each of the numerals in the combined hundreds and thousands positions in said number into code combinations of electrical impulses other than assigned` for said numerals in the tens positions in accordance with said five-element code and means at said observing station for impressing simultaneously at a second time signal impulses defining said com-'- bined numerals in said hundreds and said thousands positions in said number on said iive conducting elements comprising said second channel. A

2. In a data transmission system, a transmission channel, iive separate independent conducting elements in said channel corresponding to ive elements in a permutation code, means connected to said channel for translating any numeral in the units place l in a three-digit number into signal impulses in accordance with combinations in said live-element code requiring for transmissionV changes in the conditions of four of said conducting elements only, while said fifth conducting element remains unchanged in one of its two possible conditions, and means for translating I combined digits in the tens and hundreds places in said number into single code combinations requiring changes in the conditions of all of said .ve conducting elements.

3. In a data transmission system, an observ- 'y signal impulses in accordance with separate pert9 mutation codes to identify separate portions oi* a: multidigit` number instantaneously a plurality of decoding devices' at said receiving station con Ynectedy individually to'` Sa'id channels, locking v,means and unlocking means for a -first of'said' devices, a plurality o'i indicators connected indi-r vidually to said devices, mean-s connected to said locking means `for locking said first of sa'id devices in response to the reception of a first particular code combination by `a second of saiddevices, and means; connected to said' unlocking means, for unlocking'sai'd first of said devices in response to the reception of a second( particular codecom- Vbination by said second of saidv devices.

. 41 In a data transmission system, an' observing station, an indicating station, a plurality of sepa- ,with said codes; av plurality of separate inde-- pendentI indicating devices at said indicating sta-- tion fory indicating said portions simultaneously, relay decoding circuits individual tot each of said' indicating devices, intermedia-te said indicating devices' and said channels, two' of said; decoding circuits connected to one of said channels, and' means for conditioning oney of's'ai'dtwo decoding circuits to respond only to particu1ar'permuta f5. In a data transmission system, a'receiving sta-tion,y a ilrs-t` group of relays thereatv selectively" responsive to the reception at saidreceiving sta-` tion of combinations of signa-limpulses in accordance with a ii'rst permutation code, a second group of relays at said station, independent of said rst group of relays, selectively responsive to the reception at said receiving station oi combinations of signal impulses in accordance with a secondI permutation code, independent' of said first permutation code, a si'ngle'measuring means at a transmitting' station connected tosaid relays, a single common permutation codey signal con,- trol means connected to said ineasuring'means, for controlling the generation of combinations of impulses in accordance with both of said' codes simultaneously'tocontrol said relays, means. interconnecting said rst and saidY second relay groups, responsive to the reception of a first particular' signal code combination by said rst group; Yfor locking the relays of said second group, and means responsive to the reception of a second particular signal codev combination by said first group forv unlocking the relays of said'second' group; N Y

LAWRENCE E. MELHUISI-l. FRED J. SINGER; EDWARD SMITH. RITA KINKEAD' SMITH, Administratri of the Estate of Fullerton S.

Kinkead, Deceased.

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