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S14/Venten Bu/Bow, QAM) Oct; 23, 1928. I 1,688,872 * H. M. LEWIS DUPLEX WAVE SIGNALING SYSTEM Filed Aug. 14.1920 2 sheets-sheet 1 @im S14/venten _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 47 / l aerfaïon’` AMPLIFIER asrfcrof? '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 transmitter 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.
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