US2139103A - System of transmission - Google Patents

Description

Dec. 6, 1938. H. M. VANDERHIDER SYSTEM OF TRANSMISSION Filed April 28, 1937 3 Sheets-Sheet 1 Fadzb 72%05/22/ War Wad/0 Dec. 6, 1938. H. M. VANDERHIDER 2,139,103

SYSTEM OF TRANSMISSION Filed April 28, 1957 3 Sheets-Sheet 2.

m waxam Q41; mm Q Dec. 6, 1938. H. M. VANDERHIDER SYSTEM OF TRANSMISSION Z5 Sheets-Sheet 5 Filed April 28, 1957 m w M 3 Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE SYSTEM OF TRANSMISSION Henry M. Vanderhider, San Antonio, Tex

Application April 28, 1937, Serial N0. 139,605

12 Claims. (01. 177-451) This invention relates to systems for the transmission of intelligence and particularly to methods of and apparatus for transmitting and receiving at regular intervals the readings of one or more instruments.

In its preferred form the invention is primarily intended for radio transmission of the readings of meteorological and other scientific and engineering instruments to a distance and the registering and/or recording of these readings in various ways at definite or regular intervals.- The invention is, of course, not limited in accordance with the Preferred embodiment, for other forms of impulse transmitters other than radio may be resorted to, the apparatus may be used for the transmission of signals as set up by a key board or otherwise, rather than as taken from the registering apparatus of an instrument, and various modifications may be made of the methods and apparatus herein described.

It is a general object of the present invention to provide novel systems and methods of and apparatus for signal transmission and reception.

More particularly it is an object of the invention to provide a telemetric system wherein a plurality of types of receiving devices are each adapted for use with one or more types of transmitting devices and where improved methods of synchronizing the apparatus at two or more stations is provided.

An important feature of the invention resides in the provision of transmitting apparatus capable of sending records of instrument readings by the use of a single impulse for each digit or character in the reading.

Another important feature of the invention resides in improved synchronizing means for maintaining the transmission and receiving equipment in phase at all times to insure accurate results.

A further important feature of the invention consists in the provision of a printing type-wheel provided with a row of digits for each printing impulse sent by the transmitter, together with means to select the row to be printed in accordance with the order of the impulse.

Another important feature of the invention resides in the provision of receiving mechanism adapted to print with typewriter mechanism the readings of instruments as sent from a transmitter, where one impulse is sufficient to actuate each key so that no code need be resorted to for the operation of the system.

Still another feature of the invention resides in the provision of a novel chart recording device for use with the above system and transmitter.

Further features of the invention consist in the novel correlation of the transmitter, signal conducting system and receiver) whereby accurate results are obtained at all times and the information desired is given visually or in printed form, as letters or other characters'or as a charted curve.

Other and further features and objects of the invention both as to method and apparatus will be moreapparent to those skilled in the art upon a consideration of the accompanying drawings and following specification wherein are disclosed several exemplary embodiments Jof method and, apparatus, typesof transmitters being illustrated adapting for use with several types of receivers and receiving apparatus being shown available for use with various of the types of transmitters, it being understood that such combinations and modifications may be made in the apparatus and systems as fall within the scope of the appended claims without departing from the spirit of the invention.

'In said drawings:

Figure 1 is a diagrammatic showing of apparatus for transmitting the reading of a single instrument;

Figure 2 is a diagrammatic and schematic showing of apparatus for receiving and printing a record of the reading of an instrument, transmitted for instance by apparatus such as shown in Figure 1;

Figure 3 is a front elevation of the printing wheel and associated equipment of Figure 2;

Figure 4 is a side elevation, partly in section, of apparatus for feeding and printing on a timed tape for use with the equipment of Figure 2;

Figure 5 is a perspective view of a contact arm and contact brush thereon;

' Figure 6 is a schematic showing of synchronizing apparatus of the mechanical type;

Figure! is a view similar to Figure 1 showing a transmitting arrangement making use of dual transmission frequencies;

Figure 8 is a plan view of a. chart type recorder;

Figure 9 is a vertical section on line 9-9 of Figure 8;

Figure 10 is a vertical section on line III-40 of Figure 8;

Figure 11 is a schematic and diagrammatic view of a key type printing receiver;

Figure 12 is an axial section through a wheel type indicator; and

tion shows in greater detail than this a number of features of the; actual impulse transmittin and receiving mechanisms which form "no real part of the invention. It is conceivable that the I "'---with the arm impulses representing the readings of various-instruments or other intelligence may be trans mitted and received on any conventional apparatus. While radio transmission is preferred,-ob'-. viously line wire, sub-sea, orunderground cable,

light beam, or any other well-knownand con ventional transmission means may beresorted to. For the, sake of simplicity in connection with the present "invention, radio transmitters and; receivers have been shownmerely diagrammatically, and even; the apparatus ,for keying thev transmitter and converting the energy of the receiver for' the operation of the. recording or indicating devices have been shown only schematically and not with the intention of providing the most desirable equipment'for the purpose."

In the earlier forms of the'invention it was essential to provide," loh 'the finde'r jdialfat the transmitterj as jrria'ny contacts as were provided on the instrument'dial"in"order1 ableto tr ta 'Q th,e" a ue' lqt hei Seaw ed- .i d a f i ece n n' j; as' essential that the printing means'have as 'nya m 'ms as there were contacts at the fihderf'lhismade the apparatus cumbersomeand complicated. In

the form of apparatus shown in Figures l and 2 of the present drawings, a systemcf transmission and reception is disclosed in-which the number of contacts'o'n the finder disc-is materially'reduced, and sending and receiving l s' by means of digits disposed in the various columns-i. e., units, tens, hundreds, etc., as required. This permits the use of but twenty-contacts to send numbers up to 99 and requires only the printing digits to 9 at the receiver.

Referring now to the drawings, there isshown in Figure 1 at III the apparatus directly asso ciated with an instrument whose readings are to be transmitted. The insulating disc I I is provided with a contact l2 for each unit of reading of the instrument and on the shaft l3 actuated by the instrument itself is mounted a suitable arm l4 having at its outer end a brush for engaging with the various contacts l2 so that an electric circuit may be closed with the contact |2 corresponding to the instant reading of the instrument. v r I Associated electrically with the apparatus in is the finder apparatus |5 comprising an insulating disc l6 having peripherally disposed contacts in two sets, those numbered l1 corresponding to the tens position, and those numbered IE to the units position of digits in a number. It is not considered necessary to show apparatus for more than two position transmission, since any further positions require mere duplications. of the apparatus about to be described.

The shaft 20 is arranged to be continuously rotated atuniform speed by suitable apparatus, not shown, such as clock work, a synchronous motor, or the like, and the shaft preferably makes on the order of one revolution in from one to five minutes. This shaft carries an arm 2| arranged to successively engage the contacts and I8 as the arm rotates. There are ten contacts |8 representing the units digits 0, 1 to 9, inclusive, and there are as many contacts I! as the desired digits in the tens position. Each of these contacts I1 is connected by a suitable wire 22 to a corresponding tens position contact 23 on the instrument dial These contacts 23 are spaced in a separate circle from the contacts j.i|2jand'eachjhas the arcuatespan of ten units contacts-I2. =These cbn'tacts 23 are likewise engaged by a brush on and electrically connected M. The contacts |8 are connected byv appropriate wires 25, each to their corresponding contacts l2. There will be as many contacts 1|2 representing the digit 1 as there ar'e contacts 23, and likewise for each of theot'hefdig'its of the units position. All of the, wires have not been shown since they would complicate the drawings, but those corresponding to the zero contact l8'have been shown as. con- "nected to the respective zero contacts l2 on the instrument dial) In a like manner, all the other corresponding unit contacts will'be connected to I'I orf|8 One-contact |'l will always be connected 'throu gli'it s wire- 22 with the Contact :3 on which the brush' ot arm I 4 is resting in accordance'with "the"instrumentreadingyso that the-arm 2| will close the above described circuit in accordance 'with'the tens reading;- and then-will pass on and close a circuit with a-cont'wit IS in a like'manner in accordance with aunit reading, sothat two impulses indicating the reading of the instrument will be sent for each rotation of the arm 2|.

In order that-these impulses, both of the same length; 'maybe avail-able at the receiver for conversion into a visible'or'printed indication, they must have a definite time relationship to each other and to a starting point in the rotation of the arm 2|. For convenience this starting point is arranged ahead of the tens and units contacts on disc |6 and is shown as a synchronizing contact 35, preferably of arcuate extent at least twice as great as that of the contacts I! 01' I8. If the arm 2| rot-ates once per minute, it will be seen that the synchronizing contact will be engaged thereby at the beginning of each minute interval and will close a circuit through the wire 28, primary of transformer 29, wire 3|, battery 32, wire 36, to the contact 35, energizing the transmitter for the sending of an impulse at least twice as long as an instrument reading impulse.

"I'he time interval between any synchronizing impulse and the following "tens impulse will determine the operation of the receiving apparatus for a proper showing of the tens position reading. likewise, the interval between the forming of a synchronizing contact and a cirrelation to each other serve to send any numeral fromOto99.-"

- If desired,-the-reading of more than-one instrumentcan be transmitted by the single finder arm 2I inthe manner described in the earlier application. It will be seen that in the present drawings the contacts I! and I8 occupy only 180of-the periphery of-thediscli and could "be condensed into less space thereon sothat the receiver 40 is 'shownconnected through transformer M to the magnet of "a suitable-relay 42, which on the receipt of any impulse by the receiver draws down its armature 43-and closes a local circuit through the battery 44 and relays 45 and 46 connected in parallel. The relay '45, as shown, is a slow acting-relay and is suiliciently energized to act on its armature 41 only when the impulse is as long as that sent by the synchronizing contact 35, while the relay 46 is quick acting and is energized to operate on its armature 48by anylength impulse. As seen'in-Figures 2 and. 3, the shaft '50-:is driven fromaclock work-| or other uniform speed source of power; It is' arranged to make one revolutionin approximately one second .less time thanl'a revolutioniof .the shaft 20. .The

shaft 50 carries a detent disc 52 having asingle notch 53 in its periphery which is engaged'once per'revolution by the detent 54 on the opposite end of a centrally pivoted arm from the armature '41. It will .be seen that on the receipt of a long synchronizing impulse, the armature 41 will be attracted,willlift the detent 54 and release the disc 52 and the shaft 50, to permit a full rotation to be effected before the detent again stops the disc and shaftand permits the arm 2I to catch up. In this way substantial synchronization between the transmitter and the receiver is effected in a simple manner so that very cheap driving mechanism can be used.-

On the shaft 50 is mounted the printing or number wheel 56 which has on its periphery sets of printing characters or numbers for printing on a tape 51 moved transversely of the wheel by mechanism not shown. Printing is eifected by pressing the tape down to the type'on the wheel by means of a presser foot 58 carried on the 'end of the arm 59 supporting the armature 48,

This arm is pivoted at 60 and the foot normally retained out of contact with the tape, buton the receipt of each impulse the magnet 46 causes a printing stroke of the paper against the type character which is positioned beneath it at the moment.

The particular type positioned beneath the tape is determined by the interval existing between the release of the detent disc 52 by the receipt of the synchronizing impulse and the re- I determined. by observations. I

'set of the unitsmust correspondto the varcuate space covered by the contacts I8 at the transmitter, and a like arrangement is necessary for the tens type. The disposition of the units? and tens type on the wheel must be in accordance with the disposition of the units and -.tens contacts on the-finder disc, and with this arrangement thereceiver prints foreach revolution of the type wheelv a-;- te ns and a units? digit exactly in accordance-with the tens? and units? contacts engagedby the arm I4. moved by the instrument whose read-- ingis to be transmitted.

If the instrument whose reading is transmitted does not fluctuate rapidly, then the transmitter and receiver shafts 20 and, 50, respectively can be operated very. slowly; but, if, for instance,

are to be transmitted are in a freegballoon, re-

ity, .and barometer readings ,may changerapidly andit' willbe desired-to have faster-operation of the transmitter andreceiver shafts to v givea continuous record at the receiver of-these chang ing conditions as the height ,o,i'. -thea balloon is The devices of, Figures '1, 2, andbemade;

to transmit. numbers larger, than 3 99 without re- .sortingito a jhundreds positionsetpf contacts and printing;- heel by using. two ,digitsdn. the ftens" positiomtThu 111 u d im r e -7 in the tens; position and in ;.the ,f-g nits" -=position.-

The signal impulses i ric luding mgdii 65mchronizing mayxbe considered as a feodefi and v the.disc..l5 ;for providing the impulses a fcode the instrument or instruments whose. readings.

plateiindicativeof all'of the magnitudes of the conditions measuredby the instruments, associated therewith, while the'disc I 0, and it s instrument may be consideredas means to select the proper code from the plate to represent the existing magnitude of the condition being meas ured. The receiving apparatus including the synchronizing mechanism and means to convert the code to mechanical movements can be considered as the code translating means, while the printer can be designated as means to express the magnitudes. I

In Figure 4 is shown, moreor less schematically, apparatus for feeding tape to a tape wheel such as that ofv Figure 3 in which the tape can be-provided with pre-printed markings indicating time intervals so that a finished tape can be studied with instrument readings shown in relation to time. For this purpose the tape must be accurately driven continuously in spite of stoppage of the printing wheel for synchronizing.

In this constructiontape 51' from a roll T is moved adjacent the surface of the printing wheel or wheels 56' by means of a tape feeding roller I50, cooperating with a resilient roller I5I. This feed roller isequipped with aworm wheel I52 driven from the large worm I53 fixed on shaft 50' which is driven from a suitable motor 5| by means of pinion I54 andgear I55 fixed to the shaft 50'. The printing wheel 56' is equipped with a sleeve I56 loosely journalled on the shaft 50 and having a flange I51 pressed against the hub of the gear I55 by a spring I58, thus constituting a slipping clutchwhich permits the wheel to be stopped by the operation of the detent on the detent disc 52' without stopping the operation of the tape.

It may be desired to print the record on the not r'eeei'vepr open reports.

'tape in small type to reduce the over-all size of the apparatus and the tape, and yet to be able to read the markings as they occur without-too close inspection; For-instance," the tape may-be run behindthe instrument board of an airplane to which'meteorological reports" are being transmitted, and in this case a light "30 in arefiector I6I can be arranged'behind 'the tape to project the shadow of the markings on thetapeonto a ground glass screen'l62 at the far end: of a hood 163 which may all be behind the instrument board "Hit-With this type of apparatus,- the cured' near the "end thereof so that the-curved surface of the springcanbedragged' over the contacts to engagethem lightly; but with suiiicient pressure to conduct thesmaII amount-Zof current necessary for keying the transmitter.

' In 'Figuredthereds shown 'amechanic'a1 arrangement' for insuring theproper starting of thereceivinginstrum'entshaft only" on the: re-

" a multilobed camdisc II.-

disc II.

ceipt of 5 a long or"; synchronizing -irnpu1se.- In Figure 2 this operation is'efiected'by the slow acting magnet 45 which does not release'the detent on'th'ereceipt =ofa short'or readingfimpulse. "-In Figure 6jthe shaft 50' for the printing wheel carries the detent disc 52' as well I as :the

additional detent disc'-6 8. A 'secQnd'shaft'GS,

adapted to be driven from a separate source of "power such as" a springmotor at a greater-speed than 'theshaft 50',"-carries a-de'tent disc 10 and g A detent 'IZ'on the center-pivoted arm 13 cooperates with the singie notch in disc 68 and is'released only by'the operation of one' of*thecam lobes "on the The discs 52' and I0 have-peripheral notches under the control respective of detents' l5 and 16 on arms jointly movable by the striker 11 on the end of an arm actuated by the armature 18 of magnet 19. The local circuit of this magnet is closed by relay operated through the transformer II from the radio receiver. 0n the receipt of an impulse or short duration the magnet I9 is energized, draws down its armature 18, causing the Striker 11 to-release both detents l5 and I6. Shaft 65 then begins to rotate, but shatt 50' is retainedstationary by detent'12. The short impulse ceases and the detent I5 is returned to its notch before the cam lobe II is effective to release detent 12, so that synchronizing is not improperly effected in the eventthat the receiver is tuned-in after'a synchronizing impulse is sent but before an instrument reading impulse is sent. i i

When a long impulse is received, however, the magnet 19 is retained energized long enough'for the detent 12 to be released by a-oam lobe-14 so that the shaft '50 is then'free to rotate for a full revolution since there are only single notches in discs 52' and 68. The number of lobes of the disc II is not important, but it is I notches in the periphery of disc 10 so that shaft 60 is stopped as soon as possible after having performed its function. h v

In Figure 7 there is disclosed an alternative -form of transmitting-equipment which makes use of a radio transmitter .85 capable of sending signal'saat two different carrier frequencies, each -frequency1adapted." to bekeyed by its respective transformer 86, In this-arrangement thein- 'strument dial is the. same-as that described in -connection .with Figure. 1,-and while the finder -dialr may be -cthesame, 71119-81 been shown as slightly different having the -tens" contacts I?! onannarcof different radius than the units" contacts I8 and having :two arms 88 and 89 for contacting with; them respectively. These arms are-spaced angularly atleast the, distance of the :-arcuateextent of the ftens contacts. The first frequencyof thetransmitter, that controlled by the transformer 86,:is used solely for the sending of the synchronizing impulse, and for this purpose is connected-by wires and 9| through the local battery,- thearm 88, and the synchronizing. contact 192;,- :Theotherv frequency is used for sending the various impulses corresponding "to the digit; positions forthe instrument read- 5; 1i 4. For use -with'this-i-transmittena double frenquencycreceiver is necessary, one frequency operating a magnetifgr. releasing the printing wheel arfor'sy'nchronizing purposes, and the other a magr:net for giving-theiprinting impulseto the tape. @The operation willibe' obvious from the descrip- .-tiori.of thereceivervfor useainponnection with the wtransmitterof Figure lpwThe only difference will be thatthemagnetsliand 46 of-Figure 2 will be'operatedfrom the two frequencies of the receiver rather than in accordance with the lengths ofrthe' impulses.-.-

It may be preferred under certain conditions to chart-a curve 'of theireadings-of one or more instrumentsrather :thant'o'prlnt a tape in figures or' to otherwiseindicate or record, and for this purpose,-* receiving equipment embodying the mechanism of 'Figures'8,.-9, and 10 may be resorted to..- :Here the recordiis dotted on a paper chart or disc I00 which is rotated slowly about its center IN by any suitable clockwork mechanism. Such charts may be timed to rotate once in twenty-fourhours, seven days, or any other desired interval; With accurate timing of the drive mechanism, thechart may have indications of hours "and minutes or the like thereon in the form offilines I02 concentric with'the pivotal axis I03 of the'pen'arm I04 carrying at its outer end a suitable marking device.

This pen arm is movable over the chart under the action of a cam I05, the shape of which may be varied to suit circumstances, that shown being symmetrical about a longitudinal axis and providing movement outward for the operating stroke of the-pen during l80'of' revolution of the cam. The other 180 may merely return the pen or maybe used 'for other recording as desired. The pen arm .is equipped with a roller cam-follower I05 held against the cam at all times by-ahelical spring The cam I05 is secured to the shaft I06 driven through the gear IOTby any suitable clock-work mechanism adapted to' synchronize or substantially synchronize the :rotation -ofthe shaft with the rotation of the finder arm on the transmitter. This transmitter "is preferably of the type disclosed in my earlier application and not of. the digit position type.

preferred that there be the same-number as The shaft I06-is equipped with a detent disc 75 I08 having a .singIenotch in its periphery to be engaged by .thedetent, I Il9 and stoppedonce per revolution for synchronizing'purposes in exactly the same manner. as described. in connection with magnet IIO upon't'he receipt of a longsynchron- ,lizingimpulse' r I f V The pivot I03 -for the ipen armis a shaft both l" the adjustable portionofthe .frame 112 ofsthe through a "corresponding l magnet rotatably and slidably fitted in a sleeve III in mechanism and is supported by the eoilfspring II 3 i'n such .a manner-as to hold the marking tip of the, pen above thep pe f thocharta T armature I14 on thedower endof this shaft I03 is attracte dby the magnet ;I I5 onthe receipt of eachinstrument, reading impulse to draw, the

pen'into, marking engagement with thepaper, forming adot, The series of dots from successive sweepsof the penarm dot a curve recording .the successive readings of the instrument. Of

course, the chart is previously calibrated in concentric circles Ior the particular instrument so i -.th atthe values of points onthe chart canbe read atwill. v, a

The slow-acting and pen depressing magnets are c onnectedior operation from the output. of

a conventional radio set in a manner already de- Q usedias a;referencevpoint,w-if desired, in studying the curve loi instrumentfreadingsi The adjustable,.portijon,ll2f of,the frame H2 is manually l 'struments a .re ,recorded, there; may be given,

ceive the second or units" numbergwliereby an instrument reading is recorded.

.The second terminal of'ealch of; the magnets I2I'is connected by, a common busbar I3I to a local battery 132'through the contacts' of arelay I33 to the arm I28 by wayof wire I34. Relay I33 'is operatedfthrough the transformer I35 from ,jthe receivingflset and is energized ever'y time an impulse waved; [If at, ith ejtime ot the: receiptfoffsuch an'impul'se,the"arm I28 is"on'the contact n 'urnberedj"10, then a 'circuitilis' closed then aj secoridftimpulse islpr' ted, If

when the am 12 engages ureepat cgiiqmterjei 3, then, a 3,is printed showing at 'al of 13,as

' the ins'trument reading. ,Aft'e'rthis reading, it

is desirable to provide, a space prior to' the next reading which' may be from the same or another instrument; as previously "describe (1, and this spacing is alternativelyaccomplished once; per revolution, or once after the reading" .allocated to) each instrument, by means of ajpontaet' I36 engaged by the arm I28 and dire'ctlyclosing ribed-tim u es io :Q -S Q I Zmg pulsespreferablyoecurring when the penis near the-center,p.the;chart,. will result in the draw- :ing .of,-a dotted circle on-the chart which can be In Figure ll iisshown an extremely simple similar device. The, keys I I20 numbered respeetiVely'O to9 represent the keysof mechanism of the typewriterstyle. and each is provided with a magnet I2I so associated therewith that upon energiaation, the key is' drawn down to operate af' type number corresponding to the key numher to print on a tape or sheet as desired. One

drives an arm I28 which passes overa series of contacts mounted on the insulating disc I29. The first group of these contacts numbered 0, 10, '20, 30, 40, 50, correspond in number and position to the tens position contacts on the finder disc at the transmitter, and the secondgroup of contacts numbered 0 to 9, inclusive, correspond in number and position to the units contacts on the finder at 'the'transmitter. Thezero contact of the tens group is connected to the zero contact of the units group and the two, by means of wire I30, are connected to one terminal of the magnet I2I of the'zero key. Likewise, the tens" contact representing 10 is connected to the units" contact representing 1 and to the magnet of the key bearing the number 1, and so on through the whole set so that when the hand closes the circuit about to be described, a single tens number is printed on the tape or sheet which is then spaced, as in a typewriter, to reprior to orelfterthereeording for each through the local batteryjI3'I' theoircpitfto themagnet l23, The synchronizing niagnet"l2l is Y connected'in oi'rcuit with the ma mas; and'local battery I32 to operate ina manner ali'eadyjdv scribed. The synchronizing "impulse fect in, printing, since at the; time. t

printing magnet 'c i d lt is made by the arm, i 28, although 'if desired, arm f could rest on afcontactfwhichw ould print'a key 'to' indicate; the time,thej nature or the indication, the,v location of nesenu or someuother' desired ji'ntormatio '.I..ikew i se,'fwhere sei'erel in- P printing recorder torfuse with the ,m'ulti-position ,ik s which W is b n m digit'tr'ansmitter,offFigure It isisho'wnlargely. f schematicallyand intended for connection to the Ioutput of a jconventional radio receiver or other The arranged inconjunction with gtnatfbr Figure 1 to, indicate the"'fsource of "the I reading signals.

For instance. an airplane may, get: Weather reports from different stations-Q Each station can have a number or symboilarratiged at its trans 'mitter at a definite 'andi'difierent ,ans'ulagr position on the finder dis'cT to operate the receiver to print ,this symbol once per revpl utionfof the finder. Thus each' reading may lie/preceded or I succeeded by a number representing the sending station; thus 9 46 when 9 is the station and 46 thereading.

Figures 12 and 13 illustratea portion of areceiving apparatus intended'solely to provide indications for visual observationv of .the' reading of an instrument as transmitted by, for instance, the apparatus of Figure 1 or 7. The whole indicating apparatus is shownas enclosed'in a substantially cylindrical .housing' I15." Suitably mounted therein for rotation area .pair of number wheels I16 and I" havingthe peripheral cylindrical flanges I18 each carrying a plurality of groups of numbers thereon from 0 to 9. The

numbers are consecutively, arranged on each 'flange and there are as many groups thereon as clutch detentslater to bedescribed, the, groups being spaced circumferentially' from each other and in equal number on the two wheels. A suitable window I19 is provided in the housing for observing the single number on each wheel which is placed opposite, the window by the mechanism so that the reading of aninstrument transmitted to the apparatus can be taken. A

The two cup-shaped wheels arespaced apart as shown and concentrically mounted for rotation within the space between them is the clutch apparatus or sign-re t a qfnmay. be

wheel I80 composed of a pair of discs spaced" as therearegroups of numbers on its outer flange.

A sleeve I86 ext'endsfrom the left hand disc of wheel I80 out through appropriate bearings and, mounts thejgear I81, rotated by the pinion I88 driven from the motor I 89. This motor is of the type describedin'conn'ection with previous figures and is adapted to rotate the clutch wheel at approximately the samespeed as the finder arm at the transmitter. A detent disc I90 is mounted on the sleeve I86 and synchronizes the operation of the clutch wheel with-the finder by means of the detent I9I and its associated mag-' net I92 which releases the detent for synchronizing purposes on the receipt of a synchronizing impulse as previously explained.

The number wheels are equipped with suitable braking means, not shown, to hold them in whatever-"position they maybe placed in spite of rotationof the clutch wheel hollow shafts within their bearings.

Normally, the wheels are stopped with the zero of the wheel and the beginning of' a blank space on thejunitsf wheel opposite the window. With the clutch wheel positioned with 'the'detent I9 I in its single notch, the clutch fingers I84 take into the notches I85 which are'positioned properl'y for that purpose. When the synchronizing with it by the action of the clutch fingers held into the notches by the'spring I93. On the receipt of the impulsefor the "tens" position indicated by wheel I'II, its 'elutch arm iswithdrawn from the corresponding notch by the action of a stationary magnet I94 operating on its armature and moving the rod .I 95 looselym'ounted in sleeve I86 and pivotally secured at I96 to the opposite end of the corresponding clutch arm. The wheel is thus deprived of its driving force and stopswith that number on its face opposite the window which corresponds to the tens number contact engaged by the finder arm. A like operation takes place then in connection with the units wheel which is permittedto stop in the proper position to represent the units number neces sary for the proper indication of the instrument reading.

In each case the number positioned adjacent the window is dependent on the time interval elapsing between the synchronizing impulse and the impulse necessary to operate either the magnet I94 or the magnet I91 to release the proper clutch arm. It will be necessary to provide blank spaces on the wheel flanges so that the movement of the units wheel, which starts at the same time as the tens wheel will not bring any figures thereon in position until the tens wheel has had an opportunity of moving as far as the 9 thereon, if necessary. Thereafter, movement imparted to, the units wheel brings its numbersinto position for stoppage as required.

In order that the clutch arms I82 do not reengage the wheels at the next notch I85, shown spaced only 90 from the first one, and again start moving the number wheels, a shield I98 is pro- 1 mitted for the operation of both the tens and the units wheel by providing four notches I85. Appropriate adjustments permit a larger or smaller number of notches to be used. The clutch arms riding up on the surface of these shieldsare thus prevented fromengaging any notches during 180 of rotation. This assures that the numerals appearing before the window are available for at leasta period of one-half revolution of the clutch wheel. When the clutch arms drop off of the shieds, the ensuing notches to-be engaged by them will be positioned from the the clutch reengages a-notch. When this notch is brought back to the starting point, the wheels are reset to'receive the next movement trans- 'mitted to them and the whole operation is repeated. I

In order to use this form of receiver with the transmitter of Figure 1, a selector somewhat like that shown in connection with Figure 11 is necessary to select the magnets I94 and I9! to operate with the ,tens or units impulse. This selector can be extremely simple, having only two contacts thereon, one for the tens of arcuate extent equal to that-of the tens contacts on the finder, and a similar one for the-units. j I

The device is particularly adaptable for use with a multi-frequency transmitter, such as shown in Figure 7, where one frequency can be used for'tens..and another for units, and synchronizing can be eifected by an additional frequency or by either one of the'two frequencies by the use of a slow acting relay. I

The device shown is arranged to operate with only two number wheels, but obviously could be extended to any desired number of Wheels in a manner which need not be described since it would comprise a simple duplication of parts. A larger number of clutch notches and hence a greater number of groups of figures on each wheel will insure a longer reading" period for each numberand a shorter period in transit, and may be desirable. .4

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. Apparatus for repeating instrument readings at a distance comprising a transmitter, a receiver and a conventional channel therebetween,

a measuring instrument at the transmitter adapted to indicate a plurality of digits, 2. single rotary finder at the transmitter operable to periodically find the plural digit reading of said instrument, a single rotary device at the receiver, means to maintain said finder and rotary device in substantial synchronism including the sending of a synchronizing signal once per finder revolution, said finder being arranged to cause said transmitter to send one impulse per revolution for each digit in the instrument reading spaced in relation to the synchronizing signal to represent the position and magnitude of the digit and means at the receiver actuated by said rotary device on receipt of each impulse to indicate the corre sponding digit in its proper position.

2. Apparatus for repeating instrument readings at a distance comprising a transmitter, a receiver and a conventional channel therebetween, a measuring instrument at the transmitter adapted to indicate a plurality of digits, a single rotary finder at the transmitter operable to periodically find the plural digit reading of said instrument, a single rotary device at the receiver, means to maintain said finder and rotary device in substantial synchronism including the sending of a synchronizing signal once per finder revolution, said finder being arranged to cause said transmitter to send one impulse per revolution for each digit in the instrument reading spaced in relation to the synchronizing signal to represent the position and magnitude of the digit and means at the receiver actuated by said rotary device on receipt of each impulse to print the corresponding digit in its proper position.

3. Apparatus for duplicating the reading of an instrument of the single dial and pointer type at remote points comprising a transmitter, receiver and conventional channel between them, said transmitter including means to periodically resolve the single point instrument reading into transmitted signal impulses one for at least each of two digits therein, each impulse representative ,of the position and magnitude of its corresponding digit, said means sending a single synchronizing impulse at the beginning of each period from which the said signal impulses are arbitrarily spaced and means at the receiver to translate said arbitrary spacing into indications corresponding in position and value to said instrument reading.

4. Apparatus for duplicating the reading of an instrument of the single dial and pointer type at remote points comprising a transmitter, receiver and conventional channel between them, said transmitter including means to periodically resolve the single point instrument reading into transmitted signal impulses one for at least each of two digits therein, each impulse representative of the position and magnitude of its corresponding digit, said means sending a single synchronizing impulse at the beginning of each period from which the said signal impulses are arbitrarily spaced and means at the receiver to translate said arbitrary spacing into printed digits corresponding in position and value to said instrument reading.

5. A transmitter for sending over a conventional channel the reading of an instrument of the single dial and pointer type comprising in combination, means to periodically resolve the single point instrument reading into transmitted signal impulses, one for at least each of two digits therein, each impulse representative of the column position and magnitude of its corresponding digit, means to send a single synchronizing impulse at the beginning of each period, said first means spacing said signal impulses in column sequence from said synchronizing impulse in predetermined amounts representative of their digit magnitude.

6. Apparatus for transmitting the readings 01 a single digit and pointer instrument to a distance, comprising in combination, a code plate having a single contact for each figure in each column position of any such reading to represent all of the measured magnitudes thereof, means associating said instrument with said plate to energize one contact of each column position to code the instant reading of the instrument, and a brush movable to periodically engage each contact to transmit said code.

'7. Apparatus for repeating instrument readings at a distance comprising a transmitter, a receiver and a conventional channel therebetween, ameasuring instrument at the transmitter adapted to indicate a plurality of digits, a single rotary finder at the transmitter operable to periodically find the plural digit reading of said instrument, a single rotary device at the receiver, means to maintain said finder and rotary device in substantial synchronism including the sending of a synchronizing signal once per finderrevolution, said finder being arranged to cause said transmitter to send one impulse per revolution for each digit in the instrument reading spaced in relation to the synchronizing signal to represent the position and magnitude of the digit, a type wheel mounted for movement in unison with said rotary device, said wheel having a group of characters from 0 to 9 for each digit position to be sent, each group being spaced longitudinally on the wheel from the next group and circumferentially in advance thereof and means actuated by the receipt of any impulse to cause said wheel to print the digit then in printing position.

8. Receiver mechanism for printing records of multiple digit instrument readings transmitted as one impulse per digit each difierently spaced in relation to a synchronizing impulse, comprising a rotary member, means to synchronize the same with the impulse sender, a printing key for each figure required, each key, a contact for each magnet for each digit position, the contacts for each position being sequentially arranged to follow those of the next higher position, a brush movable in unison with said rotary member to engage said contacts serially to form a local circuit from a source of power to the magnet connected to the engaged contact and means actuated on receipt of an impulse to close the local circuit then formed by the brush to print the corresponding key.

9. Synchronizing mechanism for a transmitter and receiver connected by a conventional channel comprising a contactor.at the transmitter driven at substantially constant rotary speed, means to close a circuit thereby once per revolution to send a synchronizing impulse over said channel, a rotary device at the receiver adapted to be driven at substantially the same speed as said contactor, a detent to stop and hold said device once per revolution, means actuated by said synchronizing impulse to release said detent, means at the transmitter to send at least one additional or signal impulse of shorter duration per contactor revolution, said detent releasingmeans in the receiver responding only to the longer impulses.

10. Phasing and synchronizing mechanism for instrument reading transmission systems, including a rotary finder and a rotary indicator, in combination, means to drive said finder at substantially constant speed, means tending to drive said indicator at substantially the same speed, detent mechanism biased to stop the indicator once per revolution, a long synchronizing impulse initiated once per revolution by said finder, a short reading impulse initiated once per revolution by said finder at an interval subsequent to the synchronizing impulse representative of the magnitude of the reading, slow acting magnet a magnet for operating Y cooperating with the detent to release the same, 7

said magnet acting only on receipt of said long impulses.

11. Receiver mechanism for'repeatedly printing records of multiple digit instrument readings transmitted as one impulse per digit, each spaced in spaced relation to a single-synchronizing impulse so as to determine its 'column'position and magnitude, comprising in combination, a clockwork, a record tape, means actuated by said clockwork to drive said tape past a. printing position, a printing wheel rotatable transversely of said tape and slightly spaced therefrom at a printing position, means driving said wheelfrom said clockwork, means to stop and hold said wheel against rotation once per revolution, said means being rendered ineffective on the receipt of a synchronizing impulse, a set of printing members on said wheel for each column to be printed, said sets being in laterally spaced positions on the periphery of the wheel and also in staggered relation circumferentially and means to cause printing cooperation of the tape and nearest printing digit on receipt of each instrument read ing impulse.

next higher position for engagement by a brush carried by said rotary member to form a local circuit through its magnet and a source of current, means actuated on receipt of an'impulse to close the local circuit then formed by the brush to print the corresponding key, a magnetactuated spacer key to move the paper on which the keys print, and a contact closed once per revolution of said rotary member to deliver current to the spacer key magnet.

HENRY M. VANDERHIDER.

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