No. 706,740.-
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`n. A. FESSENDEN.
`WIRELESS SIGNALING.
`(l‘ppliention ?led Sept. 28, 1901‘)
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`Patented Aug. l2, I902‘
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`UNITED STATES PATENT OFFIc '
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`REGINALD A. FESSENDEN, OF MANTEO, NORTH CAROLINA.
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`WIRELESS SIGNALING.
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`ESPEGIFICATION forming‘ part of Letters Patent NO. 706,740, dated August 12, 1909.
`Application ?led September 28, 1901. Serial No. 76,336. (No model.)
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`To ail whom it may concern:
`Be it known that I, REGINALD A. FEssE'N
`DEN, a citizen of the United States, residing
`at Manteo, in the county of Dare and State
`of North Carolina, have invented or discov~
`ered certain new and useful Improvements in
`Wireless Signaling, of which improvements
`the following is a speci?cation.
`‘
`The invention described herein relates to
`certain improvements in selective signaling
`in systems where the signal is transmitted by
`Waves or impulses, and has for its object the
`generation at one station of persistent signal
`ing impulses or waves differing in character—
`e. g., period-and to the generation of beats
`by the waves or impulses and the em ploy
`ment of suitable receiving apparatus at the
`other station responsive only to the combined
`action of waves oriimpulses correspondingin
`period or other characteristics to those gen
`erated.
`The invention is hereinafter more fully de
`scribed and claimed. I
`In the accompanying drawings, forming a
`part of this speci?cation, Figure 1 is a dia
`grammatic view of a form of apparatus adapt
`ed to the practice of myinvention. Fig. 2 is
`a similar view of a modi?cation of the appa
`ratus shown in Fig. 1, and Fig. 3 is a graphic
`illustration of the method of signaling.
`In the practice of my invention I employ at
`the sending-station two or more sources of
`radiation constructed to generate persistent
`waves or impulses, the waves or impulses pro
`ceeding from one of the sources of radiation
`differing in character from those produced by
`the other source. At the receiving-station I
`employ a corresponding number of suitably
`tuned or adjusted receiving-conductors which
`by their conjoint action produce beats of any
`suitable character to operate an indicator,
`but are incapable of operating it except by
`conjoint action. The terms “sending-con
`ductor” and “receiving-conducto?’ as here
`in employed include all of circuits from top
`to ground, if grounded, or, if not grounded,
`from one extreme end to the other extreme
`end of the circuits, including all apparatus in
`series with the circuits, while the term “ radi
`ating portion” includes all of sending-con
`ductor from top or extreme end of the same
`to point of junction with apparatus for effect
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`ing the oscillatory charging and discharging
`thereof-such as sparking-terminals, trans;
`former-coils, armature-windings, &c. By the
`term “electromagnetic waves” as used here;
`in is meant electromagnetic Waves long in
`periodcompared with what are called “heat
`Waves” or “radiant heat.” The terms
`“tuned” and “resonant” are used herein as
`‘one to include the other.
`A convenient ap
`paratus for this purpose is shown in the draw
`ings and consists at the sending-station of
`two or more conductors having radiating por
`tions 1 and 2, each being connected to a ter
`minal or knob of an induction-coil, while the
`opposite terminal of the coil is connected to
`ground. In the form shown both the radiat
`ing portions of conductors are connected to
`the terminal or knobs 3 of the induction-coil
`5, the other knob or terminal 4 being ground
`ed. By any suitable means known in the art
`persistent oscillations are produced. This
`persistence can beeifected by so proportion=
`ing the resistance, self-inductance, and ca*
`pacity that only a small portion of the energy
`is radiated at each oscillation. This propor
`tioning can be conveniently effected in the
`manner described in the application for Let
`ters Patent ?led May 29, 1901, Serial No.
`62,301. When two conductors are employed,
`they should be so constructed and proper
`tioned as to have different periods of oscilla_
`tions-as, for example, the period of conduc
`tor 2 should be twenty-five (25) per cent.
`greater than that of conductor 1. This dif
`ference is taken here forconvenience in illus
`trating by Fig. 3; but in general a smaller
`difference, as ?ve per cent, is preferred.
`At the receiving-station I employ two or
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`more conductors 6 and 7, which are tuned to
`the respective sending-conductors by any
`suitable means, as by wires 8 and 9, which
`connect the conductors to a coherer 10 or other
`suitable wave-responsive mechanism. Each
`of the wires 8 and 9 is preferably of approxi
`mately the same length as the conductor to
`which it is connected. A grounding of- the
`receiving-conductors is not necessary, as effi
`cient signaling can be effected without a
`ground. When employing a coherer, it is
`connected, as usual, in the circuit of a bat
`tery l1 and with a relay or other translating
`mechanism 12.
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`When a spark passes between 3 and .4,
`waves of different periodicities are generated
`by the respective sending-conductors at the
`sending-station, and such waves will produce
`in the respective receiving-conductors 6 and
`7 correspondingly varying but persistent os
`cillations of potential.
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`The ?rst few oscillations of the series of
`waves will generate nearly the same poten
`tial at the ends of the coherer or translating
`device; but as the oscillations persist there
`will be a rise in the potentials at the ends of
`the coherer, the rise at one end being greater
`than that at the opposite end. The approxi
`mate equality of the potential during the ?rst
`few oscillations is graphically shown in Fig.
`3 (where the full lines represent graphically
`the potential at the terminals of the wave-ro
`sponsive device and the dotted line repre
`sents on somewhat smaller scale the differ
`ence of potential between the terminals of
`the WRVG-I'BSPOUSlVG device) and also the dis
`proportionate rise produced by one of the
`series of oscillations due to the persistence
`of the oscillations. As the coherer or other
`translating device is so constructed as to be
`unresponsive to approximately equal poten
`tials or the potentials so nearly neutralize
`each other as to produce no operative effect
`on the coherer or wave-responsive device, it
`follows that the apparatus at any receiving
`station will not respond to any waves or series
`of waves or impulses which will not produce
`or generate at the coherer or other wave-re
`sponsive device potentials differing to a pre
`determined degree, so that by properly ad
`justing the sending and‘receiving apparatus
`at the several stations any one of said sta
`tions can be signaled to the exclusion of all
`others.
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`In the form of apparatus shown in Fig. 2
`the sending-conductors are constructed with
`large capacity and self-induction, and the
`period of one of‘ them, as 2*‘, is greater than
`that of the other. I have found that good re
`sults can be produced if the period of 2“ be
`made about three (3) per cent. greater than
`that of 1“; but I do not limit myself to any
`particular difference in period. One of the
`radiating portions, as 1“, is connected to one
`terminal of a high~frequency alternator 13,
`which has its other terminal grounded. An
`alternator 13“, having a higher frequency—
`e. g. , three percent. , more or less-than the al
`ternator 13, thus corresponding to the period
`of the sending-conductor, of which it forms
`a part, has one terminal connected to the
`radiating portion 2a and the other terminal
`grounded. While not essential, it is pre
`ferred that these alternators, which are pref
`erably constructed as described in applica
`tion, Serial No. 62,301, ?led May 29, 1901,
`should be driven from the same shaft or at
`the same rate. The receiving-conductors 6“
`and 7“ are tuned, respectively, to the send
`ing-conductors and their radiating portions
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`are connected, respectively, ‘to the terminals
`of two coils 14 14“, surroundinga core 15, said
`coils and core, with the diaphragm 16, form
`ing a telephonic receiver. The opposite ends
`of the coils are connected to ground. By con
`meeting the alternators to the radiating por
`tions, such connection being preferably ef
`fected by a double-pole switch, waves or im
`pulses are generated by the sending-conduc
`tors and corresponding oscillations of poten
`tial are produced in the receiving-conductors
`and the telephone-coils, and owing to the shift
`ing of phase, as shown in Fig. 3, beats or sig
`nals will be heard in the telephone.
`Broadly my invention consists in the pro
`duction of electrical “ beats” analogous to
`sound-beats and their utilization in receiv
`ing-conductors tuned to the sending-conduc
`tors for wireless selective signaling.
`It is obvious that, as shown in Fig. 1,_the
`sending-conductors employed as radiating
`sources may have a portion of their length
`formed by a common conductor. The con
`struction here shown, while resembling in a
`slight degree that shown by Marconi, United
`States Patent No. 676,332, differs essentially
`from it in that though two conductors are used
`they are worked in parallel with one another
`and not in series, as shown by Marconi, and
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`hence instead of being insulated from each
`other are preferably (and where a spark-gap is
`used almost necessarily) electrically connect
`ed together, as shown in Figs. 1 and 2. The
`method of operation is also essentially'diifer
`cut, as instead of producing a single perio
`dicity from two conductors in series and using
`an inductance in such series circuit to pre
`vent one conductor from neutralizing by caus
`ing an initial change of phase the effect of
`the other in the method here shown two fre
`quencies are used and there is no necessary
`initial change of phase.
`It is characteristic of the invention de
`scribed herein that if two series of waves dif
`fering in periodicity and simultaneously gen
`erated are caused to persist the difference in
`phase will increase, so that if the receiving
`instruments be constructed to respond to only
`a particular difference in phase signaling will
`not be effected by a shorter persistence than
`necessary to produce the desired difference
`of phase.
`The selective system herein described is to
`be di?erentiated from that described in my
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`applications No. 18,878, ?led June 2, 1900,
`and No. 53,441, ?led March 29, 1901, in that in
`this system the indication is produced by the
`conjoint action of two or more sets of waves
`of di?erent periodicities and not by the con
`joint action of two mechanisms each sepa
`rately actuated by a set of waves, the sets of
`Waves being of different periodicities.
`I claim herein as my invention—
`1. In a system of signaling by electromag
`netic waves, the combination of a source of
`waves of different periodicities and two or
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`oscillations attain a predetermined difference
`in phase, substantially as set forth.
`6. In a system of signaling by electromag
`netic waves, the combination of means at the
`sending-station for generating two or more
`sets of waves of different periodicities and a
`wave-responsive device at the receiving-sta
`tion operative by the conjoint action of such
`sets of waves, substantially as set forth.
`7. In a system of signaling by electromag
`‘netic waves, the combination of a source of '
`waves of different periodicities, two or more
`receiving-circuits reponsive respectively to
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`the di?erent waves or impulses, and a current
`operated, wave-responsive device operative
`when the waves or impulses attain a certain
`predetermined phase relation, substantially
`as described.
`8. In a system of signaling by electromag
`netic waves, the combination of two or more
`sources producing waves of different perio
`dicities, two or more receiving-conductors re
`sponsive respectively to the different waves
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`or impulses, and a current-operated, wave
`responsive device operative when the waves
`‘or impulses attain a certain predetermined
`difference in phase, substantially as setforth.
`9. In a system of signaling by electromag
`netic waves, the combination of means at the
`sending-station for generating ‘two or more
`sets of waves of different periodicities, and a
`current-operated, wave-responsive device at
`‘the receiving'station operative by the con
`joint action of such sets of waves, substan
`tially as set forth.
`In testimony whereof I have hereunto set
`my hand.
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`REGINALD A.‘ FESSENDEN.
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`lVitnesses: ‘
`DARWIN S. WOLCOT'I‘,
`THEO. S. M'UKINS.
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`more receivers responsive respectively to the
`differing waves-or‘ impulses‘ and a wave-re
`sponsive device operative when the waves or
`impulses attain a certain predetermined phase
`relation, substantially as set forth.
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`2. In a system of signaling by electromag
`netic waves, the combination of two or more
`sources producing waves of different perio
`dicities, two or more receiving-conductors re
`sponsive respectively to the differing waves
`or impulses and a wave-responsive device op
`erative when the‘ waves or impulses attain a‘
`certain predetermined difference in phase,
`substantially as set forth.‘
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`3. In a system of signaling by electromag
`netic‘ waves, the combination of two or more
`sources producing waves or impulses of dif
`ferent periodicities and two or more receiv
`ing-conductors responsive respectively to the
`di?ering waves or impulses and‘a wave-re
`sponsive device operative by such waves or
`impulses when they attain a certain predeter-i
`mined difference in
`phase, ‘substantially as
`set forth.
`4. In a system of signaling by electromag
`netic waves, the combination of a generator,
`two or more sending-conductors adapted to
`produce waves or impulses di?ering in peri
`odicity, two or more receiving-conductors
`tuned to the sending-conductors, and wave
`responsive device operative by the oscilla
`tions in the receiving-conductors when the
`oscillations attain‘a certain predetermined
`difference in phase, substantially as set forth.
`5. In a system of‘signaling by electromag
`netic waves, the combination of two or more
`sources of persistent waves or impulses of ‘dif
`ferent periodicities, two or more receiving
`conductors responsive respectively to waves
`or impulses produced by the generators, and
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`a wave-responsive device operative by the
`oscillations in the receivers only when said
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