Oct; 23, 1928. I 1,688,872 * H. M. LEWIS DUPLEX WAVE SIGNALING SYSTEM Filed Aug. 14.1920 2 sheets-sheet 1

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_bu/bow, QAM) Oct. 23, 1928. . 1,688,872 H. M. Ll-:wls DUPLEX WAVE SIGNALING SYSTEM

Filed Alllg. l4­ 1920 ` 2 Sheets-Sheet 2

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'5) ` @MME '-Èyáëawma Patented (letÜ 23, 1928. y 1,688,872 `iJNl'l'ED STATES PATENT GFFICE.

'HAROLD lVI. LEWIS, 0F LONG BRANCH, NEW JERSEY.

DUPLEX WAVE SIGNALING SYSTEM.

Application filed August 14, 1920. Serial No. 403,560. It has heretofore been the general practice audible-beat heterodyne methods may be in wave signaling systems to effectively iso used to produce an audible note in the tele late, so to speak, the receiving apparatus from phone receivers, or to furnish a rectified or the transmitting apparatus at t-he same sta pulsating current to an indicating instru 60 tion. It has also been proposed in simul ment. As is well known, this method of taneous radio transmission and reception sys using a beat frequency produces no appreci tems, to provide aso-called“balance”between able distortion of the incoming signal energy, the transmitting apparatus and the receiv and hence makes possible the reception of ing apparat-us at the saine station in order radio-telegraph and radio-telephone signals that the energy produced at, or radiated by,` in a particularly clear and easily readable the shall not be. effective on, nor manner. interfere with the independent functioning` It has been pointed out that the invention of the receiving apparatus. It is well known contemplates the continuous production of that an absolute “balance” between the trans~ energy at the transmitter in order that a re 15 initter and receiver at the same station is ceiver at the same station may be supplied difficult to obtain, while rough or approxi with the proper amounts of the necessary mate balances may be readily effected in vari local continuous oscillations of suitable ous well known ways. strength and frequency for the reception of One feature of the present invention is that signals from a distantly located transmitter. 75 it does not require an absolute balance to be If, therefore, two distantly located stations maintained between the transmitter and re each comprising a transmitter and receiver, ceiver at the same station, since a portion of and each using the same beat or third high the energy produced at the transmitter is frequency above good audibility is selected supplied to the receiver for the actuation and for use at each station, the stations will be 25 operation of the receiving apparatus. The found to be mutually dependent one upon invention involves, however, the use of a the other, to the extent that the stopping of rough or approximate balance between the either transmitter will be noted at both re transmitter and receiver at the same station ceiving stations. The reason for this is that vso that the amount of energy obtained from energy from a. distant transmitter which is 85 30 the transmitter may be regulated and sup assumed to be continuously radiating energy plied to the receiving apparatus in the proper but not transmitting signals, may under cer amounts, In this connection it is contem tain conditions be received on the antenna plated to utilize a continuous or undamped of the local station which is assumed to be wave transmitter opera-ting continuously, to transmitting. Since the energy of the dis 90 35 provide local high frequency oscillations tant station and the energy of the local trans for reception purposes when notl being used mitter is effec-tive upon the local receiver, the for the transmission of signals. two frequencies will be combined in the local Another feature of the invention conteni receiving apparatus `­to produce the chosen plates the use of the local continuous oscilla third frequency which is above good audi 95 tions obtained in the proper' amounts from bility. In this way signals transmitted from the transmitter, for the purpose of combin either station will be heard both at the local ing such oscillations with the incoming en station and at the distant receiving station. ergy to produce a. beat frequency or readily ln order that this simultaneous or duplex amplifiable high frequency above good audi operation of the two systems may be effected, 100 bility in the manner set forth in UnitedStates it is necessary that the frequencies of trans Patent No. 1,342,885. Briefly, the method of mission of the two stations differ by the fre reception disclosed in this patent consists in quency selected as the beat frequency at both converting the frequency of the incoming receiving stations. - oscillations down to some predetermined and When two’stations are operating in the lower value of readily-amplifiable high fre manner above described,'both having chosen quency oscillations above good audibility the same beat frequency, it is possible for which may then be amplified and finally de either station to “break” or interrupt the tected and indicated to render the voice or other instantaneously. ’ By the expression “frequency above goo 110 audiothe reception frequency of modulationsunmodalat-ed audible. continuous audibility” is meant a frequencyî which, i ­­l ile waves, sinne form of chopper or the 'usual it may still be audihio, is of Stich high ` 2 1,688,872 that it does not impair' the reproduction of third or superaudible high frequency, which speech. _ are then indicated by the telephones 17 in the Various suitable arrangements ­tor making well known manner. If unmodulated con. ‘ a. portion of the energy produced at a trans« ' tinuous waves are to be received, the switch mitter eiiective upon a receiver at the same 18 may be opened to effectively place in cir< station, and for utilizing the same or associat cuit with the rectifier 16, some form of chop~ ed antenna under certain conditions for si~ per 19 in order that an audible note may be multaneous transmission and reception pur produced in the telephones. If :it is desired, poses, as well as other features and advan however, a second _local source of high fre tages of the invention, will be understood quency oscillations may be provided, such as from a consideration ofthe following descrip« the source 19’ for combining the third or tion in conjunction with the drawings, in superaudible high frequency oscillations with which: the local oscillations in the manner of the Fig. 1 illustrates the use of two associated well known audible-beat heterodyne. When antennae for transmitter and receiver, respec the ocal source 19’ is employed, the switch 18 tively, at the same station; ` should shunt the chopper or tikker 19. Fig. 2 illustrates an arrangement of trans In the operation of the transmission and mitter and receiver in which loop antennae reception system of Fi . 1, it is necessary are utilized; y that a generator of hig frequency oscilla Fig. 3 illustrates the use of two coupled tions of a suitable frequency be provided and loop antennae for transmitter and receiver, re that it be maintained in continuous operation spectively, having means for varying the bal at the transmitter. In this connection, there ance therebetween; is no limitation as to what the fre uenoy of F igmi illustrates the use ot a single loop the oscillations so generated should Je except for the purposes of both transmission and re that the frequency should be above good audi 90 ception and having means for varying the bility and chosen in such a manner as to differ balance between the transmitter and receiver from the frequency of the incoming oscilla circuits at the same station; tions to he received, by a third high frequency Fig. 5 illustrates the use of a single an which­ is also above good audibility and pref tenna earth system for both recept-ion and erably a readily-amplifiable high frequenc . transmisison; and y Care should also be taken to so associate‘t 1e Fig. 6 illustrates the use of` a single loop antenna earth systems 1, 2 and 5, 6, respec« antenna for both transmitter and receiver tively, so that only a portion of the energy which is a special application useful for short produced at the transmitter shall be made distances and extremely short wave lengths. eíi'ective upon thereceiving apparatus asso H10 In Fig. 1 the antenna earth system 1, 2 may ciated with the antenna earth system 5, 6. be considered as representing a transmitting In Fig. 2 a transmission and reception station comprising the antenna, including the system is illustrated which is substantially loading inductance 3, and having a continu similar to that described in connection with ous wave generator 4. Any well known Fig. 1. In Fig. 2, however, the antenna 105 means for modulating the energy radiated in earth systems have been replaced hy loop accordance with signals to be transmitted may antennae >20, 21, respectively, the generator be utilized. The receiving system at the same 22, condenser 23 and loop 2() forming the station comprises the antenna earth system transmission system. As in the case of Fig. 5, 6, the loading inductance 7 and primary 1, the loop 21 is suitably associated with the condenser 8. The antenna system 5, 6 is loop 2O so that a portion of the energy pro adapted to be brought into resonance with the duced by the generator 22 at the transn'xitter, received waves by means of the inductance 7‘ shall be made effective upon the receiving and condenser 8. The usual secondary circuit apparatus associated with the loop 21 of the 50 9, 10 is also tuned to t-he frequency of the re receiving system. A rectifier 11 is associated 1715 ceived waves. 11 is a rectifier for the purpose with the receiving antenna and a­ circuit 12. of converting the combined incoming energy 13 is provided which is tuned to the third and local oscillations obtained from the as~ high frequency obtained by combining the sociated transmission system 1, 2, 3, 4 to pro incoming energy with the oscillations oh» tn La duce continuous oscillations of a third high tained from the transmitter. A high fre« 120 frequency above good audibility in the cir quency amplifier 25 adapted to amplify the cuit 12, 13~­the capacity 12 and inductance third high frequency is interposed between 13 being of proper values to bring the circuit the 11 and the second detector 26, into resonance with the frequency of the os thereby making the receiving system par cillations of the said third high frequency. ticularly effective on weak short wave sig Associated with the circuits 12, 13 is the cir nals. cuit 14, 15 tuned to the same high frequency In Fig. 3, a rough balance is obtained be« as the circuit 12, 13. The second circuit is tween the transmitting loop antenna 2S an-d provided with a second rectifier 16 for the the receiving loop antenna 29 by means of a 66 purpose' of detecting the oscillations of the variable coupling 30. In this way, an opti~ 130 1,688,872 3

mum value of heterodyne energy may bc ob The circuits thus represented symbolically tained from the nransmitting` system, com may correspond with circuits 42, 45 and 46 re prising the generator 31 and the loop antenna spectively of Fig. 4. Reference character 56 28. The energy so obtained is made effective represents a pair oftelephone receivers. upon the receiving system, comprising the In Fig. 6, a circuit is »shown which is useful 70 loop 29 and the tuning condenser 32. A vac for extremely short wave lengths and dis uum tube detector 33 is ‘utilized for convert tances, limited by the strength which the os ing the'combined incoming energy and local cillations may have, for a single tube gener oscillations to produce a third high frequen~ ator, 58, to function well as both a transmit cy in the circuit 34, 35. The circuit 34, 35 ter and receiver. ‘Nhen the loop 57 is utilized 75 is directly coupled to a high frequency vac for the radiation of signal energy, the vac uum tube amplifier 36 which amplifies the uum tube 58 serves as an oscillator and gen third high or super audible frequency. A erates undamped oscillations continuously. second vacuum tube detector 37 is provided rllhe voice currents produced in the circuit 62 for detecting the resulting oscillations. The by the transmitter 63 are directly supplied 80 resulting oscillations are indicated by means to a circuit associated with the oscillating of the telephones 38. system including the tube 58 in order that In Fig. 4 a single loop antenna 39 is util the energy radiated by the loop antenna 57 ized in connection with a coupling balanc may be modulated in accordance with the ing arrangement 40, for both transmitter voice. currents inthe usual manner. When 85 and receiver. The proper amount of energy the loop 57 is used for reception purposes, produced by the generator 41 is made effec- the vacuum tube 58 serves as an oscillator rec' tive upon the receiving apparatus through tifier and furnishes the local energy for com the loopl 39 and the coupling 40. As in the bining with the incoming energy as well case of Fig. 3 a vacuum tube detector 42 is as converting the combined incoming and 90 provided for converting the combined incom local energy to produce a third readily-am ing energy and local high frequency oscil plifiable high frequency above good audibili~ lations to produce oscillations of a third high ty. The readily-amplifiable high frequency frequency above good audibility in the cir oscillations are amplified by the high fre cuit 43, 44. The circuit 43, 44 is directly cou quency vacuum tube `amplifying system 59 pled to a vacuum tube high frequency amï and are detected and indicated respectively plifying system 45. The resulting ampli by the vacuum tube 60 and the telephone 61. fied oscillations are detected by the vacuum In all of the various systems as described tube detector 46 and indicated by the tele in connection with the different figures of the phones 47. drawings, if it is contemplated that one of 100 Fig. 5 shows one of the more preferred the above described systems be used at a given forms of the invention wherein a single an station, it is only necessary that the un tenna earth system 48, 49 is employed. The damped oscillations produced at the trans antenna is divided into two parallel branches mitter be generated continuously during both each of which includes a variable oscillatory the transmission of signals and during pe circuit 50, 51. The oscillatory circuit 50 is riods of reception, and-the frequency of these preferably tuned to the frequency of the in oscillations should be such that upon combin coming signals, thus causing it to block the ing them with the incoming energy, a third pas-sage of incoming signals through that high frequency above good audibility prefer branch of the antenna. “Then thus adjusted, ably a readily-amplifiable high frequency, 110 however, the oscillatory circuit 50 is anti-res shall be produced. Beyond this requirement onant to the Alocal transmitter energy, thus there is no other limitation as to what the fre offering low impedance thereto and permit quency of the oscillations produced at the ting the latter to flow through, since the transmitter shall be. If, however, the use of frequency of the local transmitter always two stations each comprising a system as ' differs from that of the incoming signals by shown in one of the figures of the drawing, a frequency above good audibility. The os be used, it is desirable that the frequencies cillatory circuit 51 is tuned to a point where of the oscillations produced at the respective in it is nearly resonant to the local trans of the two stations differ by the mitter energy and anti-resonant to the incom frequency which has been4 selected as the ing signals. It will, therefore, be seen that third high frequency. For example, if the the incoming signals will pass freely through frequency selected as the third high fre that branch of the circuit including the os quency be 100,000 cycles, and the frequency cillatory circuit 51, while only a small por selected as one of the transmission frequencies tion of the local transmitter energy will pass be 1,000,000 cycles, then it will be necessary through that branch. In this figure the local that the other transmission frequency be transmitter is represented by the character 900,000 or 1,100,000 cycles. ' 52, while characters 53, 54 and 55 represent It should also be noted that the reception symbolically the first detector, amplifier, and of the modulated energy is 65 the second detector circuits of the receiver, accomplished without lthe distorted ltone 130 4 1,688,872 which invariably results when the ordinary prises making a portion of the energy pro form of audible-‘beat or audible-heterodyne duced at »the transmitter effective upon re reception is employed. Furtherthis system ceiving apparatus at` the same . station to is inherently more stable in operation than provideV a local source of high frequency os Ur the usual audible-heterodyne systems, since cillations, combining said local oscillations 70 a variationin either the frequency of the with the incoming energy to produce oscilla local oscillations or the incoming oscillations tions of a third high frequency above good will produce proportionately less difference audibility, and detecting and indicating the in the resulting third high frequency than said third high frequency oscillations. wouldV bc the case if an audible beat note 5. The method of permitting simultaneous 75 Were employed. The reason for both of these transmission and reception of radio signals phenomena is rather involved and in any case on the same or associated antenna Which com unnecessary, as it is an easily demonst-ated prises malring a portion of the energy pro experimental fact. duced at a continuously operating undamped 15 I claim: Wave transmitter effective upon the receiv 80 l. The method of receiving the incoming ing apparatus at the same station to provide energy in a Wave signaling system, which local source of high frequency oscillations, comprises making a portion of the energy combining said local oscillations with the in produced at a local transmitter effective upon coming received energy to produce oscilla the receiving apparatus at the same station tions of a third high frequency above good 85 to provide a local source of high frequency audibility, and detect-ing and indicating the oscillations, combining said local oscillations said third high frequency oscillations. with the incoming energy to produce oscilla G. The method of permitting simultaneous tions of a third high frequency above good transmission and reception of radio signals audibbility, and detecting and indicating the on the same or associated antenna Which com 00 said third high frequency oscillations. prises making a portion of the energy pro 2. The method of receiving the incoming duced at the transmitter effective upon' the energy in a Wave signaling system, which receiving apparatus at the same station to comprises making a portion of the energy provide a local source of high frequency produced at a continuously operating un oscillations differing from the frequency of 95 damped wave transmitter eff-ctive upon the the incoming energy by a third readily-am receiving apparatus at the same station to plifiable high frequency above good audibil provide a local source of high frequency ity, combining the said local oscillations with oscillations of a frequency differing from the incoming­ received energy to produce said said incoming oscillations by a third readily readily-amplifiable high frequency oscilla 10i) amplifiable high frequency above good tions, amplifying the said third high fre audibility, combining said local oscillatons quency oscillations and detecting and indi with the incoming energy, converting the said eating the resulting amplified oscillations. combined energy to produce said third high 7. The method of permitting simultaneous 4 (l frequency oscillations7 and detecting and in transmission and reception of unmoldulated 105 dicating the said third high frequency oscil undamped Wave radio signals on the same or lations. ' associated antenna which comprises making 3. The method of receiving the incoming a portion of the energy produced at an un energy in an unmodulated undamped wave damped Wave transmitter effective upon re signaling system, which comprises making a ceiving apparatus at the same sta-tion to pro 110 portion ofthe energy produced at the trans vide a local source of high frequency oscil mitter effective upon the receiving appara lations, combining said local oscillations with tus at the same station to provide a local the incoming received energy, converting the source of high frequency continuous oscilla combined energy to produce oscillations of a tions differing from> said incoming oscilla third high- frequency above good audibility, tions by a third readly-amplifiable high fre combining said third high frequency oscilla- ‘ quency above good audibility, combining said tions with locally generated high frequency local oscillations with the incoming energy, oscillations of a frequency at or near said converting the combined energy to produce third high frequency, converting the said last oscillations of the said third high frequency, combined energy to produce loiv frequency 120 combining said third high frequency oscilla~ oscillations and indicating the resulting low tions with locally generated high frequency frequency oscillations. oscillations of a frequency at or near to the 8. The method of permitting simultaneous said third high frequency, converting the transmission and reception of short Wave (if) last said combined energy to produce low7A radio telephone signals on the same or asso frequency oscillations and indicating the re ciated antenna which comprises making a sulting low frequency oscillations. portion of the energy produced at an un Li. The method of permitting simultaneous damped wave voice modulated transmitter ef transmission and reception of radio signals fective upon receiving apparatus at thesame (i5 on the same or associated antenna which com station te provide a local source' of high fre 130 1,688,872 5 quency oscillations differing fromthe incom ated at said transmitter is rendered effective ing energy by a third readily-amplifiable on said receiver, means included in said re« high frequency above good audibility, com ceiver for combining the energy thus derived bining said local »oscill ations with the incom from said transmitter with high frequency ing enerfcïy, converting the combined energy continuous wave incoming signal energy to 70 to produ ce the third readily-ampliiiable,high produce third high frequency above Agoed frequency oscillations, amplifying the said audibility, and means included in said re third high frequency oscillations, and detect ceiver' for detecting and indicating said third ing and indicating the resulting ampliiiable high frequency. oscillations. lll. rl‘he combination in a signaling sys~ „ 9. rl‘he method of communicating between tem of two stations adapted for inter-com two distantly located wave signaling system munication, each station comprising a high stations which comprises utilizing oscilla~ frequency continuous wave receiver and a tions of a given frequency at one station’s high frequency continuous wave transmitter, transmitter and oscillations of a frequency the difference between the operating fre differing from said lirst mentioned oscilla quencies of said transmitters being equal lto tions by a third high frequency above good a third fresse-11W above good weimar, audibility at the otherof said station’s trans means for impressing a portion- of the high mitter, and producing in each station’s re frequency energy generated by the transmit ceiver said third high frequency oscillations, ter at each station upon the receiver lat the and detecting and indicating at each station same station, means for varying the per the said third high frequency oscillations. centage of energy thus impressed upon the 10. In a wireless telephone system, a pair receiver at each station, means included in of distantly located stations each comprising each receiver for combining the energy> im~ a transmitter and a receiver, each transmitter pressed thereon from both said transmitters including a source of radio frequency contin to .produce “beat” frequency oscillations uous oscillations, the difference between the having a frequency equal to said third fre operating frequencies of said transmitters be quency above good audibility, and means in~ ing a frequency above good audibility, and eluded in each of said receivers for detect~ 30 means at each receiver for coordinating the ing and indicating said beat frequency oscil high frequency waves from both transmitters lations. , ' to provide a beat frequency equal to said fre - l5. In a high frequency signaling system, quency above good audibility. a station comprising a transmitter including ' 11. In a wireless telephone system, a pair a generator of high frequency electrical os of distantly located stations each comprising cillatory energy, a receiver, means for im loo a transmitter and a receiver, each transmitter pressing a portion of the oscillatory energy including a source of radio frequency contin from said generator' upon said receiver', means ous oscillations, the difference between the for adj ustably varying the percentage of said operating frequencies of said transmitters oscillatory energy thus impressed upon said 40 being a beat frequency above good audibility, receiver, means included in said receiver for and means at each receiver for detecting and combining said oscillatory energy with in indicating the signal components of said beat coming oscillatory energy having a frequency frequency. differing from said first-mentioned oscilla 12. The method of receiving the incoming tory energy by a third readily amplifiable energy in a modulated continuous wave sig high frequency above good audibility, means nal'ing system, which comprises making a for converting the combined energy to pro portion of the energy produced at the trans duce said third readily ampliliable high fre mitter effective on the receiving apparatus at quency, means for amplifying said third the same station to provide a local source of high frequencyoscillations, and means for 11:3 50 continuous high frequency oscillations diffen detecting and indicating said third high fre ing from the frequency of the incoming en quency oscillations. ergy by a third readily amplifiable high fre 16. The method of duplex signaling which quency above good audibility, combining said comprises transmitting in one direction be~ local oscillation with the incoming energy, tween two stations an audibly modulated 55 converting the said combined energy to pro , transmitting in the other direc 12H duce the said third frequency oscillations and tion an audibly modulated carrier wave of detecting and indicating the said third fre different frequency, and utilizing at one of quency oscillations. said stations a port-ion of the energy of the 13. The combination in a signaling system outgoing carrier wave to produce an auxil 60 of a station comprising a high frequency con iary carrier wave having a frequency dif tinuous wave receiver, a high frequency con fering from each of said waves. tinuous wave transmitter, means for estab 17. The method of duplex signaling which lishing an approximate balance between said comprises transmitting messages in one di transmitter and said receiver whereby a por rection between two stations by means of a 65 tion of the high frequency energy gener carrier wave, transmitting a message in the other direction upon a carrier Wave of a dif prises generating a carrier Wave for outgoing ferent frequency, utilizing ‘at one of said transmission, receiving an incoming carrier stations a portion of the energy of the out Wave, and combining said carrier Waves to going carrier Wave to reinforce the incoming produce a combination frequency Wave hav signal. . ing a frequency above the usual range of au 18. A radio system comprising a. station dible sound frequencies. 40 having an incoming Wave receiving circuit, 22. The method of signaling which com a source. of high frequency carrier Waves for prises generating a carrier Wave for outgoing transmitting outgoing signals, means for com transmission, receiving an incoming carrier 10 bining Waves fro-m said source with incoming Wave, and combining said carrier waves to Waves whereby inaudible Waves of a fre produce a ‘combination frequency Wave hav 45 quency different from ‘either of said frequen ing a. frequency abovetlie usual range of au cies are produced, Íand means for deriving au dible sound frequencies, but lia-ving an ampli dible incon’iing signals from said last men tude variationat an audible frequency. 15 tioned Waves. y 23. A signaling system‘which comprises 19. A system for duplex naling having ieans for `generating and transmitting to a 50 means for producinga beat requfency Wave distant station energy of an outgoing Wave vWhich is equal to the difference of the frequen frequency, lneans for receiving Wave energy cies of the incoming and ‘outgoing carrier of an incoming Wave frequency, means for 20 Waves and which is modulated in accordance ‘continually producing during transmission with the incoming and the outgoing signals, and reception a Wave having a frequency 5.5 and means for selecting and detecting said above >the usual audible ran-ge by combining Wave. . , energy ’of the outgoing and incoming wave 20. The method of duplex signaling which frequencies and means for select-ing the e'n ‘comprises transmitting a carrier wave in one ergy of the continually produced Wave. ‘ 'direction between tivo stations, transmitting >24:. A two-Way signaling system compris a vcarrier Wave of different frequency in the ing means lfor receiving and combining `the otherfdi'rec-tion, ‘and utilizing a po-rtion of the energy ’of an incoming carrier vva've With en lenergy of the outgoing `carrier Wave. at one of ergy of the outgoing carrier 'Wave frequency, said >stations in combination with the incom selecting a component of the resultant energy, ing carrier Wave to produce an auxiliary car land detectinu the selected component to pro ‘rier Wave having a frequency above the usual duce ¿inaudible frequency Wave. audiblev range. In testimony whereof I affix my signature. `21. The method of 'signaling which com HAROLD M. LEWIS.