Nov. 5, 1929.
`V
`
`_
`
`A
`.
`— 1_,_'|_EvY '
`V
`‘ELECTRICAL TRANSNIISSION OF ENERGY
`
`1,734,038
`I
`
`Filed Aug. 12, 1918
`
`'
`
`6 Shegts—Sheet
`
`1
`
`Fig.1.
`
`Imrowtor:
`Z we (Jen I avy
`fiwww
`
`fl
`
`Attorney.
`
`1
`
`APPLE
`
`1
`
`APPLE 1022
`
`

`
`Nov. 5, 1929.
`
`L. LEVY
`ELECTRICAL TRANSMISSION OF ENERGY
`
`
`
`1,734,038
`
`Filed Aug. 12, 1918
`
`6 Sheets—Sheet
`
`2
`
`Fig.7.
`
`49
`
`Iiwortar:
`Z ucien Lev]
`
`Auiarney.
`
`2
`
`

`
`Nov. 5, 1929.
`
`.
`
`-
`L. LEVY
`ELECTRICAL TRANSMISSION OF ENERGY
`
`1,734,038
`
`Filed Aug. 12, 1918
`
`6 Sheet.s-Sheet
`
`5‘
`
`F‘<fl
`..gumnnIu'
`
` 86
`
`Z'nue2zfiar:
`Per .luec"e)-1 1.‘ eu
`
`.
`
`Jftcomcq.
`
`3
`
`

`
`Nov. 5, 1929.
`
`«
`
`
`L. LEyY
`ELECTRICAL TRANSMISSION OF ENERGY V
`
`1,734,038
`
`Filed Aug. 12, 1918
`
`6 Sheets-Shee‘1': A
`
`In vent???
`_Lucz'en Levy
`/°~&.«.a«€a»
`Attorney.
`
`"'3"
`
`4
`
`

`
`NOV. 5, 1929.
`
`I
`~1_, LEVY
`‘
`-
`ELECTRICAL TRANSMISSION OF ENERGY
`
`1,734,038
`
`Filed Aug. 12, 1918
`
`6 sheets—sheet'
`
`5‘
`
`Fig. 9;
`
`INVENTOR.
`
`éy [£40523/w [eoy
`3
`ATTORNEY
`
`5
`
`

`
`Nov. 5, 1929.
`
`_
`' L. LEVY
`I
`ELECTRICAL TRANSMISSION OF ENERGY
`
`1,734,038
`
`VFi1ed Aug. 12, 1918
`
`6 Sheets—Sheet
`
`6
`
`F1’g. 12%
`
`
`
`
`
`BY
`
`1NVE1V§roR.
`
`zmm[egg
`;
`ATTORNEY
`
`6
`
`

`
`infiwatentledg. -Nov. 5, 1929
`
` 1,734,038‘
`
`UNITED STATES PAJTENT orriciéi
`
`
`
`LUCIEN LEVY, OF PARIS, FRANCE, AssIGNoR, BY MESNE ASSIGNMENTS, T0 AE:EEIcAN
`TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION or NEW YORK
`
`ELECTRICAL TRANSMTSSION OF ENERGY
`
`Application filed August 12, 1918, Serial No; 249,572, and in France August 4, 1917.
`
`I
`
`(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. I4., 1313)
`
`An application for this invention was filed
`in France, August 4, 1917.
`Radio telegraphic transmission, which, at
`thepresent time, has numerous advantages
`over transmission by wires or cables, particu-
`larly for great distances, presents also, cer-.
`tain disadvantages which limit the applica-
`tions of it.
`.
`'
`Among the principal ones well known to
`radio telegraphists must be mentioned atmos-
`pheric disturbances, confusions between the
`idiiferent signals, and the lack of secrecy.‘
`With the continual increase ofthe distances
`between the transmitting stations and receiv-
`ing stations, and the number of transmitting
`stations, the appliances at present employed V
`do not permit of sufliciently assured com-
`munications between two distant stations
`owing to the interferences of atmospheric
`currents and of other stations with the trans-
`mission to be received.
`The receiving apparatus at present in use
`consists of
`V
`(1) A primary selecting apparatus, pre-
`ceded or followed sometimes by amplifying
`appliances, and which is based upon electrical
`phenomena which are well known and which‘
`' utilize the differences of frequency of the
`wa.ves emitted by the different stations.
`(2) A detecting apparatus which converts
`the high frequency oscillations into currents
`of low frequency capable of actuating the
`telephones and other receiving apparatus
`after amplification if necessary.
`The disadvantages of
`these appliances
`when used alone are first,
`.
`The insufficiency of the selection which
`permits of hearing the stations working. with
`a frequency approaching that it is desired
`to'r‘eceive, and second
`'
`'
`The mixture in the circuit of the detector
`~ in which the telephone is placed "of the low
`frequency currents proceeding from the radio
`telegraphic transmitting stations with low
`frequency currents "due to atmospheric dis-
`turbances. Attempts have been made hitherto
`tocombine electrical circuits or acoustical
`appliances permitting of a second "selection
`based upon the differences between the said
`low frequencies so as to put in evidence the‘
`
`10
`
`15
`
`20
`
`25
`
`30
`
`.35
`
`40
`
`45
`
`50
`
`signals issuing from the receiving station,
`but these appliances have not been capable
`of any satisfactory result notably because the
`"differences existing between these frequencies
`are too small.
`V
`,
`The object of the invention is to allow of
`A
`a secondary selection which-— is absolutely
`eflicacious and which completely avoids all
`confusions likely to, arise from foreign trans-
`missions and from atmospheric currents. The
`present invention likewise is capable of effect-
`ting in place of a. single secondary selection
`a great number of successive selections, but,
`in the present state of wireless telegraphy, a
`double selection is generally sufficient.
`The method which forms the subject matter
`of the present invention consists broadly,’ .
`First, in producing in the receiving circuit
`under the action of the transmitting circuits,
`and in certain cases, by the co-operation’ of
`localauxiliary circuits, an alternating cur-
`rent of high frequency modulated in ampli-
`tude, that is to sayan alternating current of
`high frequency the amplitudes of the succes-
`sive periods of which increase and decrease
`periodically with an ultra-acoustical
`fre-
`quency that is one which is inaudible and
`« which may be called the secondary frequency.
`Second, in utilizing for reception the very
`great difference ‘of frequency between the
`modulation, or secondary frequency current
`and that of the currents pf low frequency
`produced by the atmospheric currents and by
`the stations working with the ordinary appli-
`ances.
`
`55
`
`60
`
`65
`
`70
`
`75
`
`80
`
`85
`
`The production of the alternating current
`of high frequency modulated in amplitude
`in the primary selecting circuit of the receiv-
`ing station is obtained;
`(a) By the emission at the transmitting
`station either of currents modulated in am-
`plitude like that of the receiving station which
`has just been mentioned, but much more pow-
`erful, or of high frequency currents modu-
`lated in frequency, or
`_
`_'
`(6) By appliances which utilize the phe-
`nomena of high frequency beats at one of the
`two transmitting stations or receiving sta-
`tions between two currents of high frequency.
`,The utilization of the differences of fre-_ 100
`
`90
`
`95
`
`7
`
`7
`
`

`
`2
`
`o
`
`J‘!
`
`1,734,038
`
`10
`
`15
`
`20
`
`80
`
`40
`
`55
`
`uency between the modulated current, i. e.’
`‘die secondary frequency, and the currents of
`low frequency produced by the atmospheric
`disturbances or strays and the stations work-
`ing withilthe ordinary appliances is effected
`by the addition to the resent selecting and
`primary detecting app iances, of secondary
`1‘ selecting and detecting appliances the work-
`ing of which is likewise based on the phe-
`nomena of electrical resonance.
`The secondary detecting appliance is
`enerally combined with a ticker or with a
`focal source of sustained waves tuned to a
`frequency which is slightly different from
`that of the secondary frequency derived from
`the high fr uency of emission so as to obtain
`a current (3% audible frequency capable of
`working the telephone and other receiving
`apparatus.
`’
`'
`‘ The use of the ticker and of the locally
`generated currents’ are howeveruseless when
`the secondary frequency is itself modulated
`by a low or audible‘ frequency either in ampli-
`tude or in frequency, as in the case of Wire-
`less telephony, in particular.
`The accompanying drawing shews, for ex-
`ample an installation which permits of the
`carrying out of the present method.
`A Figure 1 shews the installation of the
`transmitting station.
`.
`Fi
`es 2-, 2“ and 3 shew modifications of
`deta'
`at the transmitting station.
`Fi
`res 4, 5 and 6 are diagrammatic views
`whic ‘ shew respectively currents of high
`frequency modulated in variable amplitude,
`or variable frequency, or variable frequency
`and amplitude.
`Figure 7 shews the installation of the re-
`ceiving station.
`.
`Figures 7‘, 8, 9 and 9‘ are modifications of
`details at this receiving station.
`Figure 10 shews a modification of the
`transmitting station, in which use is made of
`an arc in place of a vacuum tube as emitter of
`sustained waves.
`'
`Figure 11 shews the receiving station in-
`stalled for the reception of transmissions
`emitted by the transmitting station shewn in 1
`Fi ure 10.
`V
`_
`~
`-
`igure 12 shows a modified s stems for
`producing secondary fre uency
`eats.-
`Figure 13 shows a dup ex system.
`As shewn in Fi
`re 1, the transmitting sta-
`tion is constitute in the following way:
`A vacuum tube 1 mounted as a generator of
`oscillations is coupledto an antenna accord-
`ing to the known methods, and is subjected to
`the action of a modulating tube 2 likewise
`mounted as a generator 0 waves but of a
`fre uency lower than emitted from tube 1.
`e vacuum tube 1 is constituted by a -bulb
`in which a vacuum has been created and
`which contains a hot filament 3, a grid 4 and
`a plate 5.
`-
`‘
`The filament 3 is connected to the grid 4
`
`by a self induction coil 6 shunted by-the con-
`denser 7 and by a self induction coil 8 on the
`one hand, and on’ the other hand to the late,
`5 by a circuit passin through the sel
`in-'
`duction coil 9 shunted by the condenser 10
`and throu h the battery 11.’ .-
`induction coil-8-is coupled ina —
`The sel
`to .the ,self_indu,c'tion_coil -9 accord-
`. neticall
`V ing to t e known methodofjconnection.
`The antenna 12- is -coninectedto a point a
`of the -self induction coil 9’ and to earth at the
`point 6 of this latter. .
`j -
`'
`The vacuum -tube 2
`is mounted in a man-
`nor similar to that o_f the vacuum; tube 1; its
`hot filament 13 is connected'ofnIthe one hand
`to the grid 14 by a circuit passing through a
`self induction coil 15, constituting the sec-
`ondary of a transformer 16,_shunted by the
`condenser 17 and a self induction coil 18 and
`on the other hand to the plate .19 by a, circuit_
`passing through the.self‘induction coils 20-
`and 21 shunted by the_co'_nde‘nser . 22, and
`through the battery 23.
`- ’
`_
`—
`'
`_
`' The self induction coils 21- and 20 are cou-
`pled magnetically to the -selfinduction coils
`18 and 6 respectively.
`‘
`The primary circuit of the transformer 16'
`is in series with the microphone 24 and a
`battery 25.
`i
`It is to be noted.that the tube 2 may be and
`preferably is of less power than the tube 1
`since it controls the energy output of the
`latter by affecting the oscillations in its grid
`circuit.
`100
`It is well known that the magnetic cou-
`pling between the grid circuit 3, 8, 4\and the -’
`plate circuit ,3, 9, 5 produces sustained oscil-
`lations at a frequency which closely ap-
`proaches that of high frequency oscillating
`circuit 9, 10.
`In like manner the oscillations of the na-
`tural frequency of tuned circuit 21, 20, 22
`develop in "this latter circuit.
`,
`It should be noted that in this appliance
`the. microphonic variation is no longer ap-
`plied-to the modulation of the waves emitted
`by the vacuum tube 1, as -in the known sys-
`tems,_ but to the modulation of alternating
`currents generated by the working of the
`vacuum-tube 2 oscillating at a high frequency
`which however is lower- than that of the
`transmitter tube 1.
`-
`It should also be noted that the oscillations
`produced by the transmitting vacuum tube
`1 are modulated at hi hfrequency (referred
`to above as the secon ary frequency) by the
`circuit 21, 20,-
`coupling, of the oscillatory
`22 with the circuit 6, 7 preferably tuned to
`the frequency of circuit 21, 20, 22 and placed
`in series with the coil 8 in the grid" circuit.
`This modulation might
`likewise be ef-
`fected b putting the system 6, 7' in series
`in the p ate circuit as indicated in Figure 2.
`The vacuum tube 1 may be replaced by a
`group of vacuum tubes which are identical
`
`70
`
`75
`
`80
`
`90
`
`95
`
`-
`
`195
`
`110
`
`115
`
`120
`
`125‘
`
`130
`
`8
`
`

`
`1,734,039
`
`3
`
`with 2 and of which the grids and plates
`are connected with each other respectively
`the filaments being heated in parallel by the
`same source without changing the spirit of
`the invention.
`‘
`-
`
`In like manner it is" possible to arrange
`in parallel instead of in series the circuits
`by which the modulation is effected and the
`circuits by which the plate voltages are ap-
`plied to the grids to produce the oscillations,
`as shown, for example, in Figure 2“.
`
`Working
`Under the action of the variations of the
`primary current due to the microphone 24,
`there are developed in the secondary 15 of
`the transformer 16 alternating voltages of
`low frequency the effect of which is to cause
`the energy of the secondary frequency cur-
`rent oscillating "‘in the circuit 21, 20, 22. to
`vary. Under the effect of this current, in
`consequence of the coupling of the coils 20
`and 6 there is produced, as in the case ofthe
`tube 2, variations of the energy of the current
`of high frequency oscillations in the circuit
`9, 10; these variations being of the secondary
`but super-audible frequency and creating in
`the circuit 9, 10 and in the antenna connected
`to this circuit variations of the_energy of the
`current passing through the antenna at this
`secondary frequency.
`In consequence of this arrangement the‘
`amplitude or the frequency or both of the
`waves emitted by the antenna are variable
`periodically as shewn in Figures 4, 5 and
`6. This modulation at secondary" frequency '
`of the current emitted by the antenna is it-
`self modulated at low frequency under the
`influence of the microphonic currents.
`It is of advantage to introduce. at w, 2 an
`oscillating circuit 26, 27, (Figure 3) tuned
`to the secondary frequency which transforms
`the current ofthat frequency in the
`plate -
`circuit into variations of voltage these vari-
`ations acting in a more intense manner to
`modulate the ‘energy emitted by the antenna.
`If in place of a radio telephonic trans-
`mission "a radio telegraphic transmission is
`desired, the transformer 16 does notplay any
`part, and the telegraphic manipulation will
`be effected for example by means of a key,
`varying the frequency of the circuit 21, or 20,
`so as to vary the frequency and intensity-of
`the secondary frequency, modulating the
`waves emitted, as shown’/in Fig. 10 herein-
`after described.
`Figure 7 shews the receiving apparatus of
`a radio station with double selection con-
`structed according to the present invention. 4
`In this arrangement use is made of vacuum
`tubes as detectors, but these may be replaced
`by all systems of detectors used in wireless
`telegraphy although the use of vacuum tubes
`offers various advantages.
`This arrangement comprises a receiver for
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45‘
`
`50
`
`55
`
`60
`
`65
`
`7
`
`-
`
`9
`
`example comprising, the coils 28, 29"'and the
`capacity 30 and a detectorqconstituted for
`example by a vacuum tube 40. The sec-'
`ondary 29, 30 is mounted in series with" the
`capacity 41 shunted by the resistance 42 in
`the grid circuit 43, 44; the value of 41 and
`of 42 must be such that the time constant of
`the grid circuit corresponds practically tothe
`secondary frequency modulating the fre-
`quency of emission at the sending station.
`In the filament plate circuit 45, 43 are
`mounted in series the battery 46 and the self
`’ induction coil 47.
`This latter is coupled to the oscillating cir-
`cuit 48, 49 provided with a detector which is
`preferably avacuum tube 50 and mounted in
`series in the grid circuit of this latter" is the
`capacity 51 with the resistance shunt 52.
`In the filament plate circuit 53, 55 are
`mounted in series the battery 56 and the re-
`ceiving telephone 57.
`i
`_
`'
`The oscillating circuit 48, 49 is tuned to
`the secondary frequenc‘ which is used for
`modulation of the higi frequency at the
`transmission end, that is to say tothe fre-
`quency of the circuit 21, 20, 22 of the trans-
`mitting station and consequently to "a fre-
`quency lower than that of the ‘receiving sec-
`ondary circuit 29, 30 Which is tuned to the
`frequency of the transmitting circuit
`’
`The working of this receiving apparatus is
`as follows :—
`The primary selection is produced by the
`selecting circuit 29, 30' which, under the in-
`fluence of the oscillations of the receiving an-
`tenna is traversed on the one hand by a cur-
`rent of high frequency modulated by the sec-
`ondary frequency derived from a transmit-
`>— 1':0!
`ting station previously described and on the ~
`other hand by the ordinary high frequency
`currents issuing from stations emitting on the
`same wave length.
`V
`I
`'
`The currents detected by the vacuum tube
`40 entering the plate circuit 43, 47, 45 are, (1)
`low frequency currents arising from at-
`mospheric currents,
`from spark stations;
`from stations of sustained waves such as are
`received by the heterodyne method of the
`usual kind, and (2) high frequency currents '
`modulated at the secondary frequency issuing’ ‘
`from the radio transmitting stationlfabove de-
`scribed. These currents, the frequency of
`which is lower than the frequency of the
`waves received by the antenna but higher
`than the frequency of other received waves
`after detection, are selected by the secondary 4
`selection circuit 48, 49 the use of which in con-
`nection with the first detection constitutes a
`characteristic of the invention.
`By virtue of this selective effect the circuit
`48, 49 is traversed solely by the currents issu-
`ing from the transmitting radio station here-
`in described which alone give into the self
`induction coil 47 a secondary frequency cur-
`
`70
`
`75
`
`80
`
`85
`
`(3U!
`
`100
`
`H0
`
`120
`
`130
`
`9
`
`

`
`4,
`
`1,734,038
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`pent capable __.of exciting oscillations in 48,
`This current is detected by the tube 50 the
`plate circuit of which is traversed by currents
`at the frequency used to modulate the sec-
`ondary frequency of the circuit 48, 49; that
`is to say of acoustical frequency, and the tele-
`_ phone reproduces the Words pronounced in
`front of*the microphone.
`_
`For the purpose of effectively separating,
`after the first detection, the extraneous low
`frequency currents from the secondary fre-
`quency currents there may be interposed be-
`tween the primary and secondary selecting
`and detecting circuits a filtering circuit which
`allows only the secondary frequency currents
`to pass.
`In this case the selfinduction coil
`47 is replaced. by a coil 58 (see Figure 8) of
`high self induction and low distributed ca-
`pacity. The two terminals of this latter are
`connected to the terminals of a self induction
`coil 59, with the interposition of capacities
`60, 61 of low value. This coil 59 is coupled to
`the coil 48 of the secondary selecting circuit
`as has been previously explained.
`There may be likewise mounted in the same
`way as shown in Figure 9 a. succession of
`coils 62, 63 with the interposition of capaci-
`ties 66, 67, 68, 69 for the purpose of obtaining
`a more complete filtration of the high fre-
`quency currents.
`Appliances amplifying the high frequency
`currents and themselves having or not select-
`ing circuits tuned respectively to the circuits
`29, 30 and 48, 49 might be interposed between
`the said circuits and the detectors without
`changing the spirit of the invention. This
`is shown, for example, in Figure 7‘ where the
`amplifier is interposed at the oint indicated
`in Figure 7 by the dotted lines etween the se-
`lecting circuit 48, 49 and the detector 50.
`This also illustrates equally well the manner
`of introducing the amplifier between the se-
`lecting circuit 29, 30 and the detector 40 at the
`point indicated by dotted lines, where it may
`likewise “be used if it is desired and the fre-
`quencies are suitable for amplification. The
`additional selecting circuit, which may or
`ma not be used, is indicated at 48’, 49’.
`mplifiers may also be used for amplifying
`the secondary or intermediate frequency by
`‘ interposing them between the filter circuit
`(Fig. 9) in the output circuit of the first de-
`tector and the secondary selecting circuit 48,
`49 in the input circuit of thesecond detector,
`as shown in Figure 9“
`-
`\ In the case of a radio telegraphic transmis-
`‘sion where the seconclaryfrcquency is not
`modulated at low frequency as in the case of
`radio telephonic transmission, a coil 64 trav-
`ersed b a current of a frequency approaching
`that o 48, 49 is coupled inagneticallyto 48
`so as to obtain beats of audible frequency with
`the current of the secondary frequency which
`circulates in 48, 49.
`
`'60
`
`(55
`
`10
`
`70
`
`75
`
`80
`
`85
`
`D0
`
`In place of using vacuum tubes as sustained
`wave emitters, use may be made of an arc of
`the Poulsen kind and the auxiliary generator
`may likewise be an are or a vacuum tube.
`Figure 10 shews an example of the appli-
`cation of the present system to transmittlng
`stations using arcs. There are two transmis-
`sion channels which may be used simultane-
`ously, one radio - tele
`aphic and the other
`,radio—telephonic, and oth are so arranged as.
`to (facilitate double selection at the receiving
`en .
`An are 70 of the Poulsen or other kind
`serving for the emission of sustained Waves
`according to the known method is in series
`in the antenna, 71 being the anode and 72 the
`cathode 73, and 74 are the electromagnets.
`The machine 75 protected against the su-
`pertensions of high and low frequenc by the
`condensers 76 and 77 placed in shunt between
`its terminals, char res the condenser 78 placed
`in parallel with t e are the positive pole of
`the machine being connected to the anode by
`‘ the ‘iron self induction coil 79, the choke coil
`80 and the negativevpole being connected to
`the ‘cathode, through the iron self—induction
`coil 81, the choke coil 82, the rheostat 83 and
`the coil of the electromagnets 73 and 74.
`In parallel with the are are arran ed the
`circuits 84, 85 and 86, 87 of which t e self-
`induction coils 85 and 87 are coupled magnet-
`ically respectively to 88 "and 89. The‘self,in-
`duction coil 89 is traversed by the high fre-
`quency currents. arising from the oscillation
`of a vacuum tube 90 mounted like tube 2 in
`Figure 1.
`~
`.
`-
`'
`The battery-23 is replaced by a condenser 91
`charged by the machine 75 through two iron
`cored coils 92, 93 and two choke coils 94, 95,
`the oscillations of the plate circuit passing
`through the condenser 91. The self induction
`coil 85 is traversed by the oscillations devel-
`oped in the circuit 88, 96 by the action of the
`auxiliary are 97 of lower power and fre-
`quency than 70, according to the known
`methods.
`'
`The are 9Z and the tube 90 are supplied by
`the same machine as the arc.70, a.continuous
`shunt current from the said machine being _
`taken between the points 0 and d.
`The condensers ‘84 and 86 have values such
`that they annul the self induction of theself
`induction coils 85 and 87 respectively for the
`frequencies of the currents above indicated
`which circulate in 88 and 89 and prevent the
`short circuiting of the continuous source.
`Under .these conditions.the action of the
`principal are 70 which emits the oscillations
`is variable at high frequency, and the modu-
`lation by the secondary frequency takes place
`under the action of the potential differences
`developed at the terminals of 85 and 87 by
`the induction of thecoupled coils 88iand 89,
`the intensity of the currents -produced by
`these potential diiferences being further re-
`
`100
`
`105
`
`I10
`
`120
`
`125
`
`130
`
`10
`
`

`
`1,734,038
`
`inforced by the effect of the principal arc
`owing to the properties of negative resist-
`ance of the arc. As
`reviously, the periods
`of these currents pro uced by the auxiliary
`arc and the tube 90 are of lower frequency
`than that to which the antenna is tuned, and
`they are different from each other.
`‘
`The telegraphic manipulation is carried
`out for example by short circuiting by means
`of the manipulator 98 some turns of 88 so as
`to vary the frequency of modulation ‘of the
`emission of the .arc 70', which modulation is
`due to the auxiliary are 97.
`The microphonic currents amplified by
`an amplifying apparatus of the known kind
`a pass through the primary of the trans-
`former 99 and modulate as in the case of Fig-
`‘ ure 1, the amplitude of the currents of the
`vacuum tube 90 traversing the coil 89 and
`modulating the energy emitted by the prin-
`cipal arc 70 as has been described above.
`Fi
`re 11 shews by way of example the
`simu taneous reception ’of the radio tele-
`graphic transmissions and radio-telephonic
`transmissions emitted by the transmitting
`apparatus shewn in Figure 10.
`The whole of the primary selecting and"
`detecting circuits is constituted as in the case
`of Figure 7, but the self induction coil 100 is
`coupled magnetically to the self induction
`coils 101 and 103 of the two secondary select-
`ing circuits 101,- 102, ‘and 103, 104 provided
`respectively with their detectors constituted
`by vacuum tubes 106, 107 as has been previ-
`ously described.
`7
`’
`The vacuum tubes 105, 106, 107 have their
`filaments heated in parallel and utilize the
`same battery 108 common to the three plate
`circuits and shunted by the condenser 109.
`The tube 106 is mounted like the tube 50
`in Figure 7, and the amplifier is showri in
`the same relation to the tube and selecting
`circuit as in Figure 7“. As regards the tube
`107, the circuit 103, 104 is connected on the
`one hand to the plate 110, and on the other
`hand to the grid 111 by passing through-the
`condenser 112 the grid being connected to the
`filament 113 by the resistance 114.
`The plate 110 is also connected to‘ the fila-
`ment 113 by passing through the primary of
`a telephonic transformer 115 the secondary
`of which is branched into the telephone 116.
`Under these conditions, the working of the
`primary selector circuit and of the vacuum
`tube 105 being the same as has been already
`explained, the self induction coil 100 is trav-
`ersed‘ by currents of low frequency and by
`currents of the secondary frequency from the
`emission of the are 97 (see Figure 10). The
`circuits 101, 102, and 103, 104 respectively
`tuned to the secondary frequencies, (the cir-
`cuit 101, 102 tuned to the frequency of the
`circuit 21, 17, 18 in Figure 10 and the circuit,
`103, 104 to the frequency of the circuit 88, 96.
`in Figure 10) oscillate at the frequencies
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`60
`
`65
`
`11
`
`‘emitted by the vacuum tube 90 andthe are
`97, respectively (see Figure 10).
`_
`In consequence_of its method of connection
`the vacuum tube 107 emits local oscillations
`at a frequency ap roximating that of 103,
`104 which, with tlie frequency induced in
`103, 104 by 100, gives beats of an audible fre-
`quency. These beats being detected by'107
`give an audible note in the telephone 116
`which, however, ceases when the frequency
`of the oscillations fromsource 97 is changed .
`by short circuitin
`at 98. (see Figure 10).
`This permits of t "e sending of radio-tele-
`graphic signals.
`A
`The‘ reception in the telephone 119 of the
`microphonic modulations is effected by the
`same mechanisms as in Figure 7.
`The production of wayes of high frequency
`modulated at"a secondary frequency in the
`receiving circuits permitting of the use of
`the double selection may be carried out by
`various modifications of the circuit arrange-
`ments "here shown both for the transmitting
`and receiving stations. The
`roduction of
`waves of high frequency, mo ulated at an-
`other high, but different frequency, may, of
`course, be accomplished in a variety of ways
`other than that shown herein in detail.- It
`is obviously immaterial, for example, to the
`broader aspects of the invention whetherathe
`variation of the high frequency current at I
`the secondary frequency 1s accomplished
`through the agency of a transformer cou-
`pling, as at 20 in Figure 1, or by other-known
`connections for this purpose; nor is it essen-
`tial that the variations be imposed upon the
`antenna circuit at any particular point.
`Likewise, the form of the generator, or other
`instrument for producing the oscillations, is
`immaterial; any known source of electrical
`variations of the proper frequency may ob-
`viously be employed- The ordinary spark
`transmitting station, if so operated that the
`wave trains succeed each other at an ultra-
`acoustic frequency, may be used in the exercise
`of this invention.
`‘
`.
`Currents suitable for the purposes herein
`described may likewise be produced direct]
`by an alternator; either by an alternator with
`inductor coils the number-of turns of which
`is variable and periodically varied, oriby the
`excitation of a normal high frequency alter-
`nator by a generator -of high frequency or
`lower frequency.
`-
`The invention may also be exercised by the
`use of beats of ultra-acoustic frequency pro-
`duced between two different waves emitted
`either by the same station upon a single an-
`tenna, or by two distinct stations upon one or
`two antennae with the use at the receiving
`station, either of a receiving circuit tuned .
`simultaneously to the lengths of these two
`waves, or of two receiving circuits respective-
`ly tuned, one to each wave, and coupled to
`a third circuit in which the secondary fre-
`
`70.
`
`75.
`
`80
`
`85
`
`90
`
`95
`
`100
`
`105
`
`110
`
`115
`
`120
`
`125
`
`130
`
`11
`
`

`
`1,734,633.’
`
`cuit29,30. a high frequency current modulated V
`at the ultra-acoustical frequency of thesbeats
`and similar to the currents , previously de-
`scribed. It is. possible to apply to this current
`the selective methods previously indicated in
`the case of the radio‘ telegraphic transmissions.
`A second local source 64, indicated in Fig-
`ure 7 in dotted lines,'may also be used-,‘ when
`desired, for the production of signals in the 7
`75
`telephone 57 by the well-known homodyneor
`heterodyne method.
`-
`'
`_
`"
`All the sustained wave stations emitting
`waves on the adjacent frequencies will like-
`wise give beats of a high secondary frequency,
`but ‘these are elimina_ted‘_by. the secondary
`selection.
`»
`:
`»
`-
`3 Stationsjwith damped emissions and very .
`-damped atmosphericcurrents will give by a
`suitable choice of the frequency of emission‘
`from the first local station and the time con-
`stants of the" detecting circuits, a. single beat
`caused byrthe short duration of the train of
`"waves.-* After primary detection, the single
`period resulting from this beat, if the cou-
`pling of the secondary selector is sufficiently
`loose has little action on the oscillating cir-
`There will not however
`jcuit of this latter.
`' generally be any vibrations with the second
`per-
`Ilocal transmitting station. This latter
`mits therefore of ‘a sufiicient selection of the
`
`770‘
`
`'
`
`'
`80
`
`85
`
`90
`
`95
`
`*
`_
`sustained waves.
`.It should be noted that in the particular
`‘ case where the continuous tension of the gen-
`erator of emission (i. e., the high frequency
`generator) is lower than the alternating ten-
`sion of the secondary frequency and in par-
`ticular if it is'zero, the energy emitted an-
`‘ nuls itself during a portion of the period.
`.
`This last described form of emission per-
`mits notonly of a double selection at the re-
`ceiving station but has the advantage of—per-
`mitting‘ comunications in duplex in a sim-
`ple manner, by virtue of the fact that the in-
`terruptions of the emission at the secondary-
`frequency are at a high rate. —For this pur-
`pose each of the stations is at once and simul-
`taneously a transmitting and receiving sta-'
`tion and comprises for example the _whole of
`a transmitting station such _as shewn in Fig-
`ure 1, and of a receiving station as shewn‘ in
`Figure '7 ; the plate of the vacuum tube 50 will
`then be supplied by the modulating current
`of secondary frequencies from the contiguous
`transmitting station by replacing the battery
`56 by a self induction coil coupled to the cir-
`cuit 21, 22, 20, so that the said tube only acts‘
`as a detector in the_ alternate periods when
`the emission does not take place. This ar-
`rangement is shown in Figure 13,
`'
`It is also possible to employ for the con-
`stitution of this duplex transmitting and re-
`ceiving station the appliances shewn in Fig-
`ures 10 and 11 or any other appliance capable
`of emitting the current specified above.
`
`100'
`
`105
`
`110 g
`
`120
`
`.
`
`12
`
`6 q
`
`-V
`
`10
`
`80
`
`N
`
`‘50
`
`7
`
`'
`
`.55
`
`uency modulated by the low frequency cur-
`rent is produced-. This arrangement is shown
`in Figure 12.
`V The different means lproposedabove per-
`mit of producin an emission current modu-
`lated to a secon ary frequency, the modula-
`tion of which itself may be modulated and
`, soon.
`The use of this current permits of as many
`selections of the frequencies of modulations
`asthere are successive modulations.
`.
`I _—:V_Vhen ‘several successive selections are em-
`* fployed, the frequencies of modulation may
`” ecome acoustical in the selecting circuits
`stmsting from the 3rd.
`In these arrangements use is made, if there
`is need of :01 frequencies of modulation, of :1:
`Selecting circuits each followed by its detect-v
`ing’ circuit, the first of these'se1ect_ing' circuits
`N
`' being'tuned.to the freqiiencypf the waves
`20
`received,
`the others to the "successive fre-:
`quencies of modulation taken inj-inverse order
`of the order of transmission. -
`i
`~
`It is likewisepossible to.iII_1pos5ei'on.g'any‘one ‘-
`of the modulations. several s1m11ltaIie:(u1s-fre-
`quencies of modulation N in number; in this
`case, there is employed at the stageaofthe re-
`ception corresponding to the said frequencies
`N oscillating circuits coupled to the circuits
`of the detector and tuned respectively to eacli
`of the simultaneous frequencies of modulation.
`It is possible to actuate in the same conditions’.
`N series of receiving apparatus absolutely in-
`' dependently of each other. An example has
`also been given (see Figures 10 and 11) of the A
`. application of these arrangements for simul-
`vtaneous modulations in
`radio telegraphy and
`- radio telephony.
`13 The rece