US1697650A - System of radiocommunication - Google Patents

Description

Jan. 1, 1929;

- L. A. HAZELWNE 'SYSTEM OF RADIOCOMMUNICATION Filed Nqv. 1, 1917 Caf slglnl :Ilm u 00/ rig .f.

ATToBNEy Patented Jan. l' 1, 1929.

UNITED sTATEs'PATENT OFFICE.

Louis ALAN HAZELTINE, or HOBOKN, NEW JERSEY, AssrGNOn, BY masiva AssIGN Manns. To waannanro, rive., A CORPORATION or DELAWARE.

- avaricia or RADIOOOMMUNIOATION.

lippnmipn anniimc-mbar4 1, 1917. `serial no. 199,743;

This invention relates to; radiocommunication, and more particularly lto oscillating audion circuits such as are used in receiving or transmitting intelligence either by speak- 5 in telephone or by telegraph.

n radio telephonyl andtelegraphy it is usual to employ one-set of apparatus for transmitting and another setv for receiving at each station. This is done because with the Ordinary arrangements of receiving apparatus a comparatively large amount of incoming energy is required to giveeasil audible response, and this requires that t e trans' mittingapparatus deliver more out-put than 15, could beobtained from a'n audion-Which is suited for receiving. Thus a large audion or other radio-fre uency generator is used for transmitting an a small audion, or other detector is used for receiving. y

In receiving sustained-wave` telegraphic signa-ls bythe heterodyne or heats method, it is necessaryl to have a loca-l oscillation otl a lslightly dierent frequency from that of the incoming oscillation and it is usual to employ an audion both to produce this local oscilla tion and to act as the detectorLj It has been recognized that in this use of the audion its sensitiveness as a detector is im roved by its being in the oscillating condition; but vapplication of this principle to radiotelephony presents special diiii'culties, which have not heretofore been overcome.` .A

I have discovered that vit is feasible to use `an oscillating audion as a detector' in radiotelephony, by employing methods and appa-l ratus hereinafter described.' By reason `ot l the Superior sensitiveness of the oscillating audion as'a detector, I am thereby enabled to use a less powerful generator at the trans- 40 .mittingi'statiom with the very desirable result that "under suitable circumstances the same audion may be used both for transinitting and for; receiving. I have also discov. ered that this apparatus and some of the methods are advantageously-applied to radio- `telegraphy, with the same result of decreasf ing the required .transmitting power.

Fundamentally the method of two-Way ra-44 diotelephonic communicationwith a single 5U oscillating audion at each station consists in operating these audions in synchronis'm. 1f

the audions are not in synchronism, fa beat note will be produced, or a distortion of the the extremely small ener 'voice tones, if the beat note bebutside the audible range, causing the voice to be uninf telligible. Ihave discovered that two audions may be o ated in synchronism when connected in distant radio stations and that transmitted from one station to theother is suiiicient to hold them in synchronism evenwhen the strength of the oscillation varies due to the voice vibrations. v

In radio receiving apparatus employing an oscillating audion operating in synclironism 05 with the incoming signal oscillation, it is desirable that-the audion be able to readily change its freqency by smalll amounts so as to accommodate itself to accidental changes in the incoming frequency. I have discov- .70 ered that audion receiving circuits of a certain general type and having certain numer ical relations between `the circuit constants have ythe property that the oscilla-tion produced by the audion will readil change its frequency with changes in the requencyof the oscillation impressed on the antenna so vas to keep the two oscillations in synchronism. This type of circuit and the necessary relation is given below. l

The receiving system consists of two tuned circuits, an antenna circuit in which the incoming signal oscillation is impressed, and a local circuit connected or coupled to the au ldion. Theaudion may be connected to the loca-l circuit in any of the various ways coinmonly known that will produce oscillations,

butY must either not be coupled to the antenna circuit at all, or else coupled very loosely thereto.` The antenna and local circuits may ao v be coupled together by any of the methods commonly used, as mutual inductance, common self-inductance,` or common capacity.

If the coupling betweenv thev vantenna and4 loca-l circuits is closer than a certain .transi-,os tion value, the-frequency of Oscillation will suddendly change by a finite amount when the natural frequency ofone of these-circuits fis lgradually changed 'and passed throught e value vfor the :other circuitioo If, on` the 'other hand` the coupling 1s than; this transition value, the frequency of Oscillation 'will change only gradually'when the natural fr uency of one of' thecircuits-is changed. I ave.v discovered' 105 that this particular condition of transit-ion coupling is peculiarly valuable in radio receiving systems in that it permits the synchronous operation referred to above.

In the accompanying drawing, n

Figure 1 "is a diagram of a. sendlng and receiving system,

`Figure 2 l.is a diagram of amodiied system adapted for long distancegoperation,

Figure 3 is a diagram showing the saving in power by transition coupling, and

Figure 4 is a diagram showing the variation in radiation of-.energy @with diierent values of coupling. c

InfFigure-l, 1 is the antenna or external circuit containing! the variable self-inductance coil 2 for tuning, and the variable series capacity 3,' connected to ground 4. Y Variably coupled to the self-inductance 2 is a coil 5, having one termina-l connected by wire 6 to theplate 7' of an audion or Vother suitable relay deviceB. The variable coupling of these'coils may be attained by pivoting one coil relativel to the other so that their axes can be variedy in their relative relation. 1" By Aaudio'nvis meant any evacuated vessel having one hot and one or morevcold electrodes and acting as a relay, whereby a rela- `tively'small alternating voltage supplied between one cold electrode and the hot electrode, producesa relatively large alternating current andfvoltage in a circuit or circuits connected betweenthe `other cold electrode or electrodes and the 'hot electrode; As commonly used, the audion hasta rectifying action in addition to this rela or amplifying action, but for the purposes this invention, a separate rectifierV or detector may be employed if desired. :f 'The other terminal of coil 5 is connected b wire 9 to self inductance 10, which is variatile'as shownfor tuning this local circuit.

The other terminal of coil 10 is connected byV wire' 11 tothe positive terminal of late battery 13. The negative side of thejattery is connected to ground through the ammeter or other suitable current indicator 14 and the telephone receivers 15. 18'is a capacity con nected between vwires 6 and 11 around coil 10 to be usedin case the inherent capacity of the audio'n and connected apparatus is insuicient toV make the localcircuit resonant.

The circuit of grid 2f) is connectedby Wirey 21- to inductance 22v which is variabl coupled `ment 29. By

to ind'uctance 10, constituting a variable grid coupling, then by wire 23 to adjustable grid battery 24, then by Wire 25 to grid potentiometer 26, and by ground and wire 34 to fila# varying battery 24, the strength of oscillation is varied, and the potentiometer 26 gives fine control ofthe grid potential, coarse 'control being obtained by varying the number of vcells in battery 24.

32 is the heating battery connected to filament i 29. through resistance 31, Wire 30, and by wire 34 to ground. t

It has been found that this conductive connection of'the grid 20 to the filament 29 through the battery 24 and potentiometer 26 for adjustingits average potential iscouducive to stability of the audion and hence to greater freedom from impulsive interference large compared with the alternating part of the grid potential, attained in Fig. 1 by tuning the plate circuit by the condenser 18 instead of timing the grid circuit, as has been common practice heretofore, permits oscillations of relatively large power to be generated, while effectively retaining the detecting property of the audion.

In operating to receive signals," the audion is most sensitive as a detector when it is oscillating independently of the received sig'- nal, which is necessary in the heterodyne reception of sustained waves. on is oscillating however, certain li1nitations are imposed, which Vary fordiiferent forms of signals to be received, as in radio telephony, or radio telegraphy with damped waves, or radiotelegraphy with sustained waves. This invention is applicable for all of these purposes and presents distinct and novel advantages over methods and systems heretofore proposed.

To determine experimentally when the coupling has the desired transition value, the` natural frequency of one of thecoupled circuits is continually varied through the tuning When an audiy point (i. e., the point at which the two circuits "o coupling is loosened so that the click'or beat note and the jump in the ammeter reading just disappear, transition coupling has been attained. This procedure is the same no matter whatform of coupling or what yaudion connection is employed, lso long as the connections are of the type described above.

Mathe-matically there is a definite and' siniple relation between the transition 'coupling and the other constants of the circuit and this is. that the. coetlicient coupling.l should 4equal the .power factorof the antenna Vvcir.- ciut. 'By ,cOeliiCient, coupling 1 with wli'erreM'lz' is the mutual'inductance between the antenna n d vlocal circuits, whose self# vinductances -are "L and, Iii .reS'P'eQtiYeIY-- By where 2.2 is the'resistance-andgthe'capacity ofv the antenna ,circuit..;;lVith otheriormsof coupling the .j coeiicientuoff couplingM is Texpressed. by otherformulas, ybut its'sign-iic-ance would generally beI apparent to onei'a'iniliar with the theoryofcoupled circuits", audit vshould still be adjusted to equal the power factor, either X3-Oily 0r .with an insignificant difference. .c Y

The curves of F the relation the voltage in the antennay required to maintain synchronous operation,- plotted 'against the relative naturalv frequencyfor-which the reza ceiving system is adjusted, for 'a power factor)v p2 ofthe antenna'circuit equal .to 0.01, andfor the three Cases: (ab)lof-:transition .couplingn marked c',f2=0.0l,; (b): otas'coup'ling of. twice the transition value, marked .c,jv2`-.f' 0.02; and (0) of a. coupling of one ha-lfthe transition value, marked 'c,2= 0.005.. These*- curvesshow for example that if'the naturali frequency is outof adjustment bjl/:ZO of 1% (pointsmt 09995 and.. 1.0005) .thevoltagej in the antenna. that will .justf'maintain synchronous `operationis aboutlltimes'as Similar conditions l ariseA in receiving' dampedwave telegraphic signals. Dampedwaves are emitted in ,cjroups-by'thesendingf ceivers which respondfmith a. musical tkme' having the group frequency. ,It is foundin practice'that an independent4 oscillation .in the receiving apparatus will cause'the rel ceived signalsftobe-louder. but the musical note will be lost, andthe signals thereby become less readable in the presence 'of "disturbances-,ss-uch as are' caused by strays. The

reason for this is that the local-oscillation* does@ not ."cox'nbinefwith successive signal lgrroups--i`nt-he same phase, but sometimes adds to and'sometimes subtra'cts from the silz'nall oscillationvand in'varying amounts; This effect is similar 'ini its general characteristicsto radiotelep'hony receiving Aw1tl1 the-two os;J

P Y which-gives vthe desired'fmusical tone.

- telephone receiveizs,f;. and-sl cilla'tions out of synchronis'm, and is obviated 'toa considerable degreeby the same receiv- 'ing circuitnsjandv relation betweenthe circuit ,n :constants- 'Thus With circuitsof the type previously described "(fof lwhich Fig'.l 1*is`v an example)/and adjusted`-i`or transitiont coupling,gthe local oscillation'can readily change slightly in frequency and fso can accommodate itselfn to. changesin'phasefot' the* successive groups. In this way the local oscilla-tion will addv to. *all* (or nea''lvfa'll )Vv of the groups arnd-.Will' greatly-am tl inf'without destroying' theiry regular er'it'idic'lcharacter Even in-.cases `WhereV itis not fou-nd 'possible to. attain this synehronizinfc"action; it will be found vdesirable adj'us h"' plingto the transitionrlv'ilue, the audionbeing also adjusted:1 so" a'sgtjo be on 1theverge ofo's cillating-,because the selectivity andf-s'ensitivcfness Willuthen.begreatestY Tlielculve'sot Fig;- jfor this case j:represent1th lf eantennavoltagejsrequired-ffor.a 'given "es-pense i'n the tis :tojfbrthe least.l (whentheflocal cir 'itfis'ne'arlyin tune -zwith the signa-lai. orftransitio icou-'f' .-...eVith zthe a'ifdiontosiillating the saine" ,apply 4:toi receivingfisustain'ed wave signals, ,esp eciallj7 ,fof short? Wave-length?? 'f Trans-i coupling;- lis'iafdvantaggeons*when. it is desired'toeniployi looseljbouple .circuit-sz in` transniiitting.; sustained-waves .produced by an/audion For il'nclosei coupling' -isenv ployed, the oscillationj having two: natural f frequencie"s.is likelytosudd'nlychange-from." oneto4 thefother. d-ueV to?any-disturbance, thus causing great,1inconvenience;-anti,v on the othenv hand, if loosencouplingis employed, a

. smaller proportion 'oi-the oiitputL of the au-A 44dion;- radiated-:fronrtheiantenna:V Thisfi's illustnated by-thecurvzefof F.ig; 4 showing the great for :1=0.02. as for'the transition value,j`re1'ft'ile neTgYmditQ-di-,Wth different Values 7, v .f ofcoupling,assumingthe cur-rent in the local circuititog-remain-constnt. -It Will 4be vseen l j that no increase of radiated-.energyoccurs Awhen .the coupling is [made 'closer rv than the as* i transition value, but tha-ta rapid decrease occurs when the coupling is looser. f

In` radotelephone v vsend-ing, "al: microphone transmitter ,36 isinserted between Wire'Q? and the ground, and having its primarycoil 37 on .co1'e`38 inductively related to 4'seconc'lary 39 lo# 4cated betxieen Wire -23zand battery' 24. v In r vorderl to vary vthe.frequency fon-radio tele-'f' graph sending by-f. 'the' 'compensating wave methods; :Jr-condenserv 42 is connected by Wire 41,=to azkev 43,' whichy is connected to ground y bywirefl. l .f j

l For long distancecommunication it is preferable to; weaken the oscillation'yat the receiving end and strengthen that. at the sending end, which byl reason ofthe transition couplin'g at each en'ldhelpsto maintain synchro- `nousoperaltilon; Iand gives greater sensitivefinessat the receiving end.` Varmtlon 'of the imY strengt-h of voscillation is. effected, asabove descrl ed, by varyingthe grid battery 24, or by varym mutual induction between coilslO pensation to beadj'usted by'trial, such as a variable capacity, or one connected in or out of circuit simultaneously with changesin the' battery; i

For long distance two-way telephonie con munication without changes in` adjustment,"

' the modification shown in Figure 2 ma. be

vas

used, employing areceving 'and asen ing audion at each station, orany other high-fre'- .quency generator, or arc in place of the 'send ing audlon. In such case the hi h=frequency sending source shouldl preferabiybe so connected as not toafect the receiving audion .at that station. This isefected by balancing the antenna. capacity, inductanoe and resistvance on both. s idesof point B by the con-f denser 3, lower coil?,a and non-inductive re' sistance r, respectively and causing 4the mu- .tual induction between the 'antenna-and.local circuits to -be 'ually divided between` coil 5 and the two coils 2. This insures thatthe .oscillations caused by sending from transmitter 36 willbe transmitted through the in' ductive couplin of coils 50, 51, 52, and wire and thence to the `antenna is figure jalso shows the ceiving audion,which.makesno difference in 4 f the results obtained withthis invention, and

isequally applicable to Figure 1L From the foregoing description, itwill be understood that the method* of synchronous loperation by transition-couplin ,and the circuits herein selected as examp es, are 4of decided advantagedn radio communication, not

ronly in 'cutting down interference, but in in'- 'creaslng the range with a 'given power, or reqpirmg yless power for a given range. Port- "a le outfits embodying this inventionhave extremely small` dimensions and light weight and have many "advantages for military and field vWork, as where quick. communication may be .desired `between moving Ao-utposts and acentral station. l

y What is claimed, is: v 5 f1. A'radio telephone s. stem hav-ing at a `F'station 'radiating and collecting means, a "single means for producing osc1llat1oi1s 1n said 'radiating means and; amplifying collccted oscillations, meansfor detecting' the collected oscillations.l 'and means for varying the radiated oscillations by voice modulation,

said oscillation producing means being continuously yin action.

- 2. A radio 'telephonefsystem having vata station asingle rradiating and collecting element, a single meansfor vproducing oscillations in said radiating "means and amplifyamplifyi other stdli ing @Ollctled scillation's, means .for detectoutgoing of il l`a" t= i`on'sy to be receive and am pflified bythe ther 'audion and receiving and oming oscillations from the nd sending andl receiving means at e s ation operable at will wi the Asame yc cuit adjustments.

. 4,. A rad lephone system employing at` 1w ,stations an audion j enerating ,80 outgoing oscillations to bel received andern plified bythe other audion and receiving andl amplifying "i omi'ng oscillations from the other statiq jeach audioncomprising a heated eleni'ent1`and two cold elements s'o con- 95 nccted in .theirfcircuit's as to generate oscillations of.' `relatively lar'e ower v'vithout substantiallrf:jimpairing t e t etectionV of in\ coming oscilation's, and sending and 'receiving means'atfeachstation operable at will 9" withthe lSan'u'circuit adjustments.

5. radicmmunicating system having at a stationasirigle radiating andc'ollecting element, an iiudionfor producing-oscillations in said radiating element and amplifying col- U6 A lectedoscillations, the gridof said -audi'on being conducjtifvely connected to the filament through circuit lmeansffor adjusting its average potential, means for detecting the collected'oscillations, and means lfor var' ing-the |00 radiated `oscillations to transmit inte ligence.

6. A radiofyc'ommunicating system having at astationa'fsingle radiating collecting element, an audion for producing `oscillations in said radiating'element and 'ampli ing colf los lected oscillationathe grid lof sai audion being conductively connected to the filament throu h circuit'means of low audio frequencyr1 rfadjusting itsaveragepotentia, means fordetecting the collected oscillations, and means for varying thera'diated oscillations -to transmit intelligence.

7.- A radio communicating system` having at a station a single .radiating and `collecting element, an audion for producing oscillations 11B insaid radiating element' andampl'iyingjcob -lected oscillations', the y'grid lof said audion being conductivcly connected to the filament "element, lanfa'ud-ion for producing oscillations in said radiating elementandfamplifying'collected oscillations, the grid of said a-udion being conductively. connected tothe '13o' filament through a battery for maintaining the average potential of the grid negative and a potentiometer for finely adjustin said potential, means forldetecting the col ected oscillations, and meansfor varying the radiated oscillations to transmit intelligence.-

9. The method of attaining synchronism between a free electric oscillation produced in one circuit by a source of continuous electric oscillations and a forced oscillation impressed on a second circuit, which comprises tuning said circuits to the forced oscillation and coupling said circuits in such manner that the coefficient of coupling is substantially equal to the power factor of the second circuit.

10. Apparatus for producing' or am lifying electric oscillations comprising a dbvice capable of producing electric oscillations, a circuit in which oscillations are generated by said device, and a second circuit in tune with the first circuit and coupled therewith in such manner that the coefficient of coupling is approximately equal to the power factor of the second circuit.

11. Apparatus for producing or'amplifying electric oscillations comprising a device capable of producing electric oscillations, a

`local circuit in which oscillations are generl ated by said device, and an antenna circuit jin tune with the local circuit and coupled l therewith in such manner that the c'oetlicient of'coupling is approximately equal to the power factor of the antenna circuit.

12. Apparatus for producing or amplifying electric oscillations comprising an audion capable of producing electric oscillations, a local circuit in which oscillations are generated by the audion, an antenna circuit coupledv with the local circuit' in such mannerthat the coefficient of coupling is approximately equal to the power-factor ofthe antenna circuit, and means for varying the natural fre quency of these two circuits while keeping in tune with each other.

13. Apparatus for relaying electric im vpulses comprising aV local circuit, means for impressing oscillations thereon, and a tuned antenna circuit coupled to said local circuit in such man-ner that the coefiicient of coupling is approximately equal to the power factor i of the antenna circuit.

14. 4Apparatus for radiotelephone receiving comprising a'tunedreceiving circuit containing an oscillating audion tuned'in syn- I chronism with the incoming signal, said cir-j cuit being coupled to the antenna circuit in such manner that the coefficient of coupling 'substantially equals the power factor ofthe antenna circuit, and a telephone receiver in' the circuit of the audion. L c. 15. Apparatus for radiotelephone receiv- Y ing comprising a tuned receiving circuit con-V taining an oscillating audion tuned in synchronism with the incoming signal, said'cvir-jA ner that the coefficient of coupling substan' tially equals the power factor. of the antenna circuit, a telephone receiver in the circuit of one of'saidcold electrodes," and means for controlling the strength of oscillation.

. 17. Apparatus for radiotelephone receiving comprising a tuned receiving circuit containing an oscillating audion having a hot` and two cold electrodes, an antenna circuit' coupled to the receiving circuit in such manner that the coefficient of coupling substan' tially equals the power'factor of the antenna circuit, a telephone receiver in the circuit of one of said cold electrodes, and a variable coupling between the circuits of said cold' electrodes for controllingthe strength of oscillation.

18. Apparatus for radiotelephone receiv-j ing'and sending comprising a tuned circuit containing an oscillating audion having ahot and two cold electrodes, an antenna circuit coupled to said local circuit in such manner that thecoeiiicientof coupling substantially equals the power factor of the antenna circuit, a telephone receiver connected in circuit with one of said cold electrodes, and a telephone transmitter connected in circuitwith the other cold electrode.

19.' Apparatus for radio receiving and sending with the same adj ustment comprising an antenna circuit, a locally. oscillating circuit coupled thereto containing a single evacuated vessel having a hot andtwo cold electrodes, .the circuit of one of said cold electrodes oscillating in ysynchronism* with said antenna'circuit and containing a receiver, and the circuit of the other cold electrode containing means for varying-the oscillations radiated by the antenna to transmit intelligence.

20.- Apparatus ing an oscillating audion having a hot and two cold electrodes, an4 antenna circuit cou pled to 4said local circuit in such manner that the'co'eicient of coupling substantially equals of-said'cold electrode, and means forv vary- 'Ling thesftrength of oscillation.

1 521.- Apparatus for radio receiving and sending comprising a tuned circuit contain- ""ing -anr oscillatin audion having a hot and? `two cold `electro es, a -tuned antenna-'circuit l H5 y for radio receiving and 'v sending comprising a tuned circuit containthe power factor of the antenna circuit, re-

coupled tosaid local circuit in such manner that the coeicientof coupling substantially equals the power factor of the antenna circuit,

, a receiver connected to one of said cold electrodes, a transmitter connected to the other of said cold electrodes, and a variable coupling between` the circuits of said cold elecceiver connected to said oscillating receiving 23. Apparatus for radio communicationcomprisin an antenna circuit, an evacuated vessel having a hot and two cold electrodes, an oscillatin .tuned local circuit containing one of said/co d electrodes and coupled to said antenna circuit in such manner that the co.-4

eliicint of coupling is substantiall equal to radiated oscillations in sending.

24. In radiotelepliony, means for` radiat` ing and -collecting energy in the\form of electromagnetic Waves, a single means for producing oscillations in said radiating means in synchronismwith the collected radiations and amplifying the same, a telephone for receiving the amplified synchronous re` ceived oscillations, and a telephone transmitter for varying the radiated oscillations whereby to receive and transmit speech in duplex witlioutchange in circuit adjustments.

25.,In a station for radio telephony the combination of' a source of continuous oscilbining. said oscillation with an incoming voice modulated signal oscillation, and means responsiveto the combined oscillations for detection. f

Signed at Hoboken, in the county` of Hudson and State`of New Jersey, this twentyseventh day of October, A. D. 1917.

LOUIS ALAN HAZELTINE.

lation, means modulating said oscillation by v vvoice control for transmission, means com-

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