E. H. ARMSTRONG.
`METHOD OF RECEIVING HIGH FREQUENCY OSCILLATIONS.
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`1,342,885.
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`PatentedJune 8, 1920.
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`INVENTOR
`61M; H. M
`BY
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`ATTORNEYS
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`1
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`APPLE 1017
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`UNITED STATES PATENT OFFICE.
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`nnwm n. anus'mono, or rams, rmmcs.
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`IETHOD OF RECEIVING HIGH-FREQUENCY OSCILLATIOHS.
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`1,342,885.
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`Speci?cation of Letters Patent.
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`Patented June 8, 1920.
`Application ?led February 8, law. Serial No. 275,744.
`ampli?cation; ?rst, there is'a tendency of
`the ampli?er system to oscillate as the fre
`quency is increased, and secondly, it is im
`possible to make the ampli?er operate well
`at more than one frequency without a variety
`of adjustments. The limit of the practical
`ampli?er at present is about 100 meters and
`the range of wave lengths from 0-100 me
`ters are unused at the present time because
`‘of the di?iculties of amplifying and detect
`ing them. High frequency ampli?ers have
`been constructed-to operate on wave lengths
`as low as 200 meters, but with only fair
`e?iciency.
`The present invention discloses a method
`of indirect ampli?cation and reception which
`operates independent. of the frequency of
`the incoming oscillations and which, there
`70
`fore, opens up the great ran e of wave
`lengths below 100 meters and maies possible,
`in fact, the use of waves of a few meters in
`length whereby radio communication by di
`rected beams of energy becomes a practical
`apposition. The present invention may also
`used to great advantage on wave lengths
`from 300 to 1,000 meters with a considerable
`gain in selectivity and sensitiveness, as com
`pared ,to any of the known methods.
`This new method of reception consists in
`converting the frequency of the" incomin
`oscillations down to some predetermined
`and lower value of readily ampli?able high
`frequency current and passing the converted
`current into an ‘ampli?er whlch is adjusted
`to operate well at'this predetermined fre
`uenc .
`I After passing through the ampli
`er, t ese oscillations are detected and indi
`catcd in the usilial manrégr. The (ilnteréngdliate
`uency is aways a " ve goo .an i iit ,
`giatqbeyond this requirement there is no othgr
`limitation as to what it shall be. The method
`of conversion preferred is the beat method
`known as the heterodyne principle, except
`that in the present system‘ the beat frequency
`is always adjusted to a point above good
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`audibility.
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`To all whom it may concern: ~
`Be it known that I, Enwm H. AnMs'rnoNo,
`a citizen of the United States, now residing
`in Paris, France, have invented certain new
`and useful Improvements in Methods of
`Receiving Hi h-Frequency Oscillations, of
`which the fol owin 1s agspeci?cation.
`This invention re ates to'a method of re
`ceiving transmitted'high frequency oscilla
`tions as in radio tele aphy or radio teleph
`ony and it vis particularly effective when
`receiving damped or undamped waves of '
`short wave len h. Another result achieved
`by the use of t - is invention is that because
`of its selectivity the interference caused by
`undesirable signals, strays, and atmospherics
`. is reatly reduced.
`e particular di?iculties overcome by
`this'invention will be understood from the
`following explanation: It is well known that
`all detectors rapidl lose their sensitiveness
`as the stren h of t e received signals is de
`creased, an that when the strength of :‘the
`high frequency oscillations falls below a cer
`tam point the response of a detector becomes
`so feeble that it is impossible. to receive sig
`nals. The application of low frequency am
`pli?ers assist somewhat up to a certain point,
`ut theinherent noise in all low frequency
`ampli?ers limits the extent to which low fre
`quency ampli?cation can be carried. It is
`alsowell known that theysensitiveness of a
`recti?er for weak signals ma‘ be restored by
`the use of the heterod e prlnciple, but/xthis
`is only a vpartial solution of‘ the problem in
`asmuch as this method can be used only in
`' certain, cases.
`A solution for the loss of Isensitiveness of ‘
`the detector for weak 'sggnals lies in the
`ampli?cation of the radio e uencycurrents
`before applying them to the etector. ‘This
`'been recognized for. some time and va
`nous forms of multi-tube vacuum tube am
`pli?ers have been developed and success
`fully employed in practice on certain ranges
`of wave le
`hs'. Because of the inherent
`The process of convertin the incoming
`capacity which exists between the elements. ‘
`high frequency oscillations ownto the au
`of vacuum tubes, this method of ampli?ca
`dible range ,may be carried out in several
`tion becomes inc
`'
`ly di?icult, as the fre
`stages and each stage may be amplified by
`quency of the oscillatlons to be received in
`crease. There, are two principal points of
`means of a multi-tube am li?er.
`e great
`advantage of this meth is that the effect
`di?iculty encpuntered in the abovemethod of
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`be either resistance or inductance coupled.
`of the output side of the ampli?er upon the
`Where selectivity is required inductance
`input side is eliminated as the frequencies
`coupling should be used and the circuits
`are entirely different. As a consequence
`'tuned by means of condensers.
`of this the limitation on ampli?cation
`I_n Flg. 2 a source 12 of incoming oscil
`which has always been imposed by the tend- .
`lations is associated with the circuit 13--14
`cncy of the ampli?er ‘to 'oscil te is re-.
`a
`preferably tuned to the incoming oscilla--'
`moved, and exceedingly great ampli?cations
`tions; a vacuum tube oscillator-recti?er 16
`- become possible.
`‘in conjunction with the circuit 15-13
`In the accompanying circuit diagrams;
`Figure 1 illustrates a simple diagrammatic
`14.—-16—17 forms , a self-.heterodyne. A
`multi-tube high frequencyi'ésistance cou led'
`adaption of 'the- invention, Figs. 2 and 3
`ampli?er 18 ampli?es energy obtained3 by
`illustrate in detail an arrangement of cir-'
`inductive couplin from the inductance 17.
`cuits and vacuum tubes whereby this new
`A detector 19 an telephones 20 detect and
`method of receiving may be accomplished.
`indicate the oscillations ampli?ed by' the
`Fig. 4 illustrates a system in which the proc
`es of conversion-and ampli?cation is car
`am li?er 18.-
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`P ig. 3 illustrates in detail the utilization
`ried out in two stageswherebv certain ad
`of my method using a. tuned ampli?er sys~
`vantages hereinafter explained are obtain
`tem wherein 21 is the source of incomuglotg ' 86
`able.
`cillations, and a vacuum tube recti '
`Referring, now to Fig. 1; the source of
`system 2_2—23+-25> converts the combm
`the incoming oscillationsis represented by
`oscillations of the incoming and those from
`a coil 1. An inductancc__2 and a capacity
`the separate heterodyne 24. The- _ circuit
`3 form a circuit prefer/ably tuned to the
`26-27 is tuned to the converted combination
`incoming frequency. -A recti?er 4 in the
`of the two oscillations. A multi-tube hi h
`90
`circuit 3-5 is a means for converting the
`t.
`' frequency ampli?er 28 am li?es the
`combined currents of the incoming energy
`ing energy heterodyned an detected by the
`and the locally generated oscillations from
`vacuum tube system 29‘and indicated by the ‘
`the source 6. A coupling 5——7 serves to
`apply the converted oscillations to the high
`as
`-tele hones 30. '
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`1g. 4 illustrates the general a
`ampli?er 8 which is ad'usted -
`frequency
`_
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`ment of circuits and apparatus in which
`to amplify well at a predetermme fre
`the rinciple 'of f
`uency conversion and
`quency; a detector 9 and telephones 10 serve
`amp i?cation .is emp oyed twice. The coil
`to detect and indicate the resulting ener .
`'31 represents the source of- the incoming‘
`- A' separate heterodync 11 is shown coup ed
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`oscillations. 3
`is a circuit tuned to
`to the circuit 9-10 and is used when re
`85
`tbs1 incoming oscillations; a separate hete
`ceiving undamped waves. By means ofthis
`e 34 is .associated with the circuit' ‘
`' systemof circuits and apparatus m
`ro
`new
`32-33. A detector 35 _recti?es the coin
`method may be utilized as follows :— he in
`bined currents which are applied to the
`coming oscillations are combined in the cir
`high‘ frequency ampli?er 38 and the ampli
`cuit 2-3 with the oscillations generated
`?ed currents again combined with local os
`locally by the source 6. The frequency-of
`cillations from the source 40 and‘ then ap
`the source 6 is adjusted to give av beat fre-~
`plied to another high frequency ampli?er
`' quency which is the predetermined fre
`43 by means of the coupling 41-1-42. The
`uency, to which the amplifier is adjusted. '
`'45
`110
`resultant energy is then detected and in
`he combined high frequency currents in
`' dicated by the detector 44~and the telephones
`we converted by means of a recti?er‘,
`45. The operation of this system will be
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`to a current of predetermined fre
`:understood from the following brief anal
`quency. This converted current is applied
`ysis:-—Suppos_e the incoming oscillationsv
`to the ampli?er 8 and ampli?ed thereby. If
`have a frequency‘ of 10,000,000 cycles per
`115
`the incoming oscillations are damped or
`second. The ampli?ers 38 and 43 will be
`modulated as in telephony, they are received
`adjusted to frequencies which may be ap
`directly by means'of the recti?er 9 and in
`proximately 1,000,000 and 100,000 cycles
`r
`dicated by the telephones 10. If the inc-om‘
`second respectively. By adjusting the
`_
`ing'oscillat-ions are undamped it is neces
`quencyIof-the local source 34 to 11,000,000
`sary to associate some auxiliary device such ,
`and passing the combined _high frequency
`as the heterodyne 11 with the second detect
`in.-.
`current through the recti?er 35 a
`ing circuit 9-—10.in the manner shown. The
`This fre
`'. quency of 1,000,000 is reduced.
`recti?ers 4 and 9 are indicated- conven
`quency is then ampli ed by the ampli?er
`tionally but they may be vacuum tubes or
`38 and combined with a second. locally ro
`crystals or any other similar suitable device. \
`duced current from 40 which is adj
`to
`The choice of the recti?er depends on sev
`1,100,000 cycles. This combine ‘current is',
`eral considerations which are well known ~
`converted‘ by means of the recti?er 39 into
`at the- present time. The high frequency‘
`a' current having a frequency of 100,000
`ampli?er 8 may be any one‘ of the several
`and this new current is
`cycles per secon ,
`types which are
`well known and it may
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`1,842,885
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`ampli?ed by the ampli?er 43. The output
`of this ampli?er is then detected and in
`dicated by means of the recti?er 44 and
`telephone 45. There is no reason for lim
`itin the process to two steps. If it is de~
`sire the 100,000 current out ut of 43 can
`be converted into 20,000 cyc es and again
`ampli?ed before passing into the detector
`44 and indicator 45. The number of stages
`of frequency conversion and ampli?cation
`which may be-employed is almost unlimited
`if the‘frcquency is lowered in small steps
`As already pointed out the great
`' each time.
`advantage of this amplification in stages is
`that it eliminates the reaction between the
`output and input sides of the ampli?er and
`removes thereby the feature which has here
`tofore always placed a limit on the ampli7
`?cation which may be obtained.
`It should be particularly noted that the
`20'
`reception of spark signals and telephonic
`speech is accomplished without the hissing
`or distorted tone which invariably results
`when the ordinary form of beat or hetero
`dyne reception is employed. The reason
`for this is rather involved and in any case
`unnecessary as it is an easily demonstrated
`ex rimental fact.
`‘_
`claim:
`1. The method of amplifying and receiv
`ing high frequency electrical oscillatory
`energy which comprises, combinin t e
`incoming energy with locally generated high
`frequency continuous oscillations of a fre
`quency differing from said incoming energy
`by a third readily-ampli?able high fre
`quency, converting the combined energy by
`suitable means to produce said readily-am
`pli?able high frequency oscillations, ampli
`fying the said third high frequency oscilla
`tlon's, and detecting and indicating the re
`sulting ampli?ed oscillations.
`2. The method of amplifying and receiv
`ing high frequency electrical oscillatory en
`ergy which comprises, combining the incom
`ing energy with locally generated high fre
`quency continuous electrical oscillations of
`a frequency differing from said incoming
`energy by a third readily-ampli?able high
`frequency, rectifying the combined energy
`to produce said readl -ampli?able high fre
`quency oscillations, amplifying the said
`third high frequency oscillations, and de
`tecting and indicating the resulting ampli
`?ed oscillations.
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`3. The‘ method of amplifying and receiv
`ing high frequency damped .wave oscillatory
`electrical energy which comprises, combin
`ing the incoming energy with locall gener
`ated high frequency continuous e ectrical
`oscillations of a frequency differing from
`said incomin energy by a third readilg
`ampli?able high frequency, converting t e
`combined emggy by suitable means to pro
`duce said rea '_ y-ampli?able high frequency
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`oscillations, amplifying the said third high
`frequency oscillations and detecting and in
`dicating the resulting ampli?ed oscillations.
`4. The method of amplifying and. receiv- -
`ing undamped wave high frequency electri
`70
`ca oscillatory energy which comprises com
`bining the incoming energy with locally gen
`erated high frequency continuous electrical .
`oscillations of a f
`uency differing from
`said incoming energy y a third readily-am
`pli?able high frequency, amplifying the said
`third high frequency oscillations, combining» 4
`said third high frequency electrical ‘oscilla
`tions with locally generated high f uency
`oscillations at a frequency near to sai third
`high frequency, converting the said last com
`bined energy to produce low frequency os
`cillations and indicating the resulting low
`frequency oscillations.
`5. The method of indirectl amplifying
`-85
`high frequency electrical oscillatory energy
`which comprises combining said energy with
`high frequency continuous electrical oscilla
`uency differing from said "
`tions of a freq
`energy by a third readily-ampli?able high
`90
`frequency, converting the combined1 energy
`by suitable means to produce said readily
`ampli?able high frequency'oscillations and
`amplifying said resulting readily-ampli?- .
`95
`able high fre uency oscillations.
`(i. The met 0d of amplifying and receiv-,
`ing electrical oscillatory energy of short
`wave length which comprises combinin the
`incoming energy with locally generated igh '
`frequency continuous electrical oscillations 100
`of a frequency differing from said incoming v
`energy by a third high frequency within the
`range of 20,000 to 250,000 cycles per second,
`rectifying the combined energy to produce
`said oscillations of said third high fre
`quency, amplifying the said third ‘high fre
`quency oscillations and detecting and indi
`cating the resulting ampli?ed oscillations.
`7. The method of receiving and amplify
`ing high frequency oscillations whereby the
`incoming energy is utilized to produce oscil
`lations of a di?erent locally predetermined
`high frequency which are then ‘ampli?ed
`and the resultant energy utilized to reduce
`oscillations of a second different, loca ly re
`determined, high frequency, which are t en
`ampli?ed, detected and indicated.
`_8. The method of receiving and amplify
`ing high frequency currents whereby the in;
`coming oscillations are combined with a sec
`ond locally generated high. frequency oscil
`lations, and the combination converted by
`suitable means to produce oscillations of a
`third high frequency, which are then ampli
`125
`?ed and the resulting ener combined with
`a fourth localliy generate
`high frequency -
`oscillations an the combination wnverted
`by suitable means to produce oscillations of I
`a?fth high frequency, which are then am
`ph?ed, detected and indicated.
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`- 9. The method of ‘receiving and multi- predetermined and ampli?ed before
`‘_ stage amplifying high frequency oscillations combined with successively di?erent locally 10
`a
`-- whereby the incoming ener ‘1s utilized‘to generated oscillations and converted to" r0
`roduee oscillations of a v i?erent locally
`uce the successive oscillations and w 'ch
`5 predetermined high frequency, which are after the last stage of ampli?cation are then
`._
`ampli?ed and the~ resultant energy" detected and indlcated. -
`utilized to rodueesuccessive oscillations of
`high frequency, which are locally '
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`EDWIN H. ARMSTRONG.
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