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Патент USA US2407312

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Sept m, Í946-
R. LoRENzEN ETAL
2,407,308
METHOD AND APPARATUS FOR SECRET SIGNALING
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Filed Jan. 1e, 1941
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Sept. l0, 1946.
2,407,308
R. LORENZEN ET AL
METHOD AND APPARATUS FOR SECRET SIGNALING
Filed Jan. 1e, '1941
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5 Sheets-Sheet 2
Sept. w; 194s.
2,407,308
R. LORENZEN ETAL
METHOD AND APPARATUS FOR SECRET` SIGNALING
Filed Jan. 16, 1941
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R. LoRENzl-:N ETAL
METHOD AND APPARATUS FOR SECRET SIGNALING
Filed Jan. 16, ~l94l
5 Sheets-Sheet 4
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Sept., M), w46.
R. LORENZEN ET AL
METHOD AND APPARATUS FOR SECRET SIGNALING
Filed Jan. 1€, 1941
5 Sheets-Sheet 5
Patented Sept. 10, 1946
¿M1308
UNITED STATES PATENT OFFICEv
2,407,308
METHOD AND APPARATUS ron SECRET
SIGNALLNG
Robert Lorenzen and Felix
New York, N. Y.
l
Spiegel,
Application January 16, 1941, Serial No. 374,790
2 Claims. (Cl. 179-15)
The present invention relates to methods and
apparatus for secret signaling.
The disadvantages of present existing com
municationg systems are: (l) the possibility of
blanketing-out or jamming the audiofrequency
signal modulation by a third party, thereby dis
rupting communication service, and (2) the pos
sibility of a third party intercepting signals that
are desired to be kept secret.
The need for new communication systems is
to obviate the above mentioned disadvantages
and shortcomings of present systems, for the
present invention introduces a multiplicity of
communication systems which can either be used
alternately or in conjunction, whenever the need
arises. Thus, if by remote chance one of the
hereinafter mentioned systems should fall into the
hands of a third party so that this third party
discovers the technique employed in the new sys
tem, it is merely necessary to adopt one of the
manifold alternate systems.
The possibility of employing a multiplicity of
2
operation of one of the manifold of communica
tion systems herein described.
One of the principal objects of the present in
vention is the application of the new principle
to radio communication systems.
Another object of the invention is to sho-w the
application of the new principle to'supersonic sig
naling, i. e., its application to communication
ysystems which employ ultra-audible waves in a
10 Imaterial
medium as a means of c-ommunication.
Stil1 another object of the present invention isV
to show how the herein described principle may
be applied to communication systems which em
_ploy electromagnetic waves of a non-radio char
15 acter as the carrier of the transmitted signals.
Typical of such systems are those which utilize
a light-beam as the means of transmission, or
infra-red rays as the carrier of the transmitted
signals, or ultra-violet as the signal carrier.
Another object of the invention is to show the
application of the present system to those com
munication systems which employ wired wireless,
alternative communication systems is obviously
of considerably greater advantage than would be
i. e., where the signals are transmitted along
the case if the number of communication systems 25
either a conductor or a dielectric guide.
Another principal object of the present in
vention is the simultaneous transmission of dif
ferent signals when but. a single carrier fre
quency is employed.
blanketing-out or jamming the conventional eX
Still another object of the invention is the si
isting transmissions lwill leave the new system 30 multaneous transmission of the desired signals
unaffected, despite the fact that the means em
and false signals, soI that, although only the de
ployed by the third party have elîectively par
sired signals are received by the two parties be
alyzed the yconventional existing means of com
tween whom communication is established, any
munication. By the employment of the new sys
outside third party receives only the false sig
tems, hereinafter to be described, the desired
nals and is thereby deceived as to the real con
communication is enabled to be continued with
tent of the transmitted messages.
out interruption or interference.
Still another object of the invention concerns
One of the objects of this invention is to show
itself with a new method of scrambling signals
were limited to three as at present, for if it is
assumed that any one of the multiplicity of the
new systems is employed, then any means for
how an inñnitely large number of diiîerent com
munication systems are made available instead
so as to make the interception of transmitted
messages impossible to any outside third party
who is not informed both as to the method of
0f merely the present limited number of avail
able systems, namely, three.
Another object of the present invention is to
show how uninterrupted communication may be
maintained between two parties, despite the fact
scrambling and the principles underlying these
new communication systems.
45
The present invention will be described Iwith
reference to the accompanying drawings, but it
that a third part may, by the process of creating
artificial noise and interference, cause the iam
ming of conventional communication systems so
will be realized that other application-5 and em
bodiments lie within the scope of the invention,
for it should be understood that the scope of the
as to result in a complete disruption of commu
present invention is so broad that only the gen
50 eral features are herein disclosed. Subsequent
nication service.
patent applications will describe the various spe
Still another 'object `of this invention shows
ciñc embodiments and give in more concrete
how it i-s possible to maintain uninterrupted
form the manifold applications and modifications
communication between two parties even though
of the principle herein described.
some third party has discovered the principle of
Fig. 1A represents the generalized set-up of a
2,407,3oe
transmitter which employs multiple modulation,l
while Fig. 1B represents a receiver which is ca
pable of receiving such multiply-modulated
transmissions.
Fig. 2A represents a transmitter wherein only
one intermediate-modulating-frequency is em
ployed, while Fig. 2B represents a receiver which
is capable of receiving such a doubly-modulated
transmission.
' Fig. 3A represents a transmitter which is capa
ble of simultaneously transmitting a number of
different signals on a single carrier frequency,
while Fig. 3B represents a receiver for such
transmissions.
Fig. 4A represents a transmitter whichV is capa
ble of transmitting both the desired as wellV assv
4
ñrst intermediate oscillation frequency fn. The
foregoing process continues, as indicated by the
dashed lines, until the multiply-modulated re
sulting signal is fed into .the amplifier-modulator
6, the output of which is employed to modulate
the nth intermediate frequency oscillator l,
whose oscillation frequency fin is some multiple
of the (n-Dth intermediate frequency oscil
lator. The output of the nth intermediate fre
quency oscillator 1 goes to an amplifier-modu
lator 8, which is employed to modulate the car
rier frequency oscillator 9. The modulated out
put- of- the carrier frequency oscillator 9 is then
either directly, or after further amplification, fed
, into a,V radiatorY Il), which in the case of radio
transmission would consist of an antenna system,
At the receiving station, as illustrated in Fig. 1B,
false signals, while Fig. 4B represents a receiver
the multiply-modulated signal is picked up by an
for receiving the desired signals.
tennai t which is connected to amplifier i2. This
Fig. 5A represents a transmitter employing
amplifier i2 is capable of amplifying the carrier
20
triple modulation in which the signals are
frequency and should have an> amplifying band
scrambled in such a manner that part of .the
width capable of amplifying the accompanying
scrambled signals modulate the first intermedi
multiply-modulated signal. After suitable ampli
ate-modulating frequency and the otherpart of
fication.V by amplifier l2. the signal is fed to de
the scrambled signals modulate-the second’inter
modulator i3, which removes the carrierI fre
mediate-modulating frequency. Fig. 5B repre 25 quency
fc and leaves only the multiply-modulated
sents a receiver for the reception of such
signal jin. The output of demodulator I3 goes to
scrambled transmission.
amplifier if», which amplifies the signal at fre
In the conventional communications system,.at
quency
jim and which possesses a band-width ca
the transmitter a signal frequency modulates a
carrier frequency, this latter being propagated 30 pable of amplifying the accompanying multiple
modulation. The output of amplifier I4 goes to
’ through space, this, in turn, is received at are
demodulator l5 which removes the nth inter
ceiver, Where, after' suitable demodulation, the
mediate modulating frequency, so that the out
original signal frequency is obtained. AsY will
put of demodulator ifa-consists of the multiply
hereinafter be disclosed, the present conven
modulated @L_-1) th intermediate modulating fre
tional method is but a very special case of the
quency. This signal is fed to amplifier I6, which.
new general principle, which -concerns itself with
means and methods for producing andY utilizingV
superimposed and multiple modulation of signals.
In order to reduce the complexity of description,
ampliiies at the ('n-Dth intermediate modulat
ing frequency` and which has an amplifying band
width suitable for amplifying the accompanying
the principles underlying multiple modulation 40
will first be discussed. Again, although later de
scriptions will utilize various combinations of
amplitude, frequency, and phase modulation, .
further simplicity of description will at this time
multiply-modulated signal. This process is re
peated, as indicated by the dashed lilies, until
be secured by making the two following assump
Demodulator ißîremoves the second'intermediate
modulating frequency, thereby leaving only the
tions: (1). amplitude modulation is employed
throughout, and (2) spurious modulation prod
only thev multiply-modulated second intermediate
being amplified by ampli
frequency remains, this
fier il, after which it is fed to demodulator I8;
signal-modulated first intermediate-inodulatingA
frequency, Tlieoutput of demodulator iS goes to
amplifier lil, which is capa-ble of amplifying the
-applicable .to other than itsemployment'in radio . :i first intermediate-modulating frequency and its
ucts are disregarded. In addition, although it
will shortly be seen that the new principle is
transmission and reception, the preliminary de
scription will restrict itself to its application to
radio communication.
Referring to Fig. 1A, which represents in block
accompanying signal modulations.
The output
up of the signals fs. Signals from l go to the am
quency. After sufficient amplification the'orig
of amplifier IS goesto demodulator 20‘ which re
moves the first intermediate-modulating frequen
cy and leaves only the original signal frequency.
diagram form a transnriitterv employing multiple SI1 ri‘he output of demodulator 20 then goes to ampli
fier 2l which ampliiies theV original signal fre
modulation, I represents either a source or pick
inal signal frequency may be taken from the out
put of amplifier 2l to actuate any suitable device,
ployed to modulate an oscillator 3 which isv oscil
lating at the frequency fn. Oscillator 3, which (if) such as, for example a loudspeaker or telephone
shall be called the first intermediate-frequency
receiver.
Having explained the general principle of mul
oscillator produces an oscillation which is some
multiple, not necessarily integral, of the- fre
tiple modulation, there will now be considered a
quency of the signal frequency. If the signal
simple, example of multiple modulation, namely,
is comprised of a band of frequencies, as would
when only a single intermediate modulating fre
be the case when the signal consists of speech
quency is employed. The symbol fs willv be used.
or music, the ñrst intermediate frequency oscil
to designate the signal frequency, which, for co i
lator will have a frequency which is some mul
venience, may consisty of those frequencies of
tiple of. the highest signal frequency. The output
which music or speech sounds are comprised.
of intermediate frequency oscillator 3'feeds into
The symbol fr will be used to represent- the inter
the input of the amplifier-modulator 4, where
mediate modulating frequency, which, in this case,
pliñer-modulator 2', the output of which is em
the signal-modulated fn frequency is amplified
we may assume to be a fixed frequency of 100,000
and then employed to modulate the second in
cycles. Similarly, the symbolfcshall‘ be used to
termediate frequency oscillator 5, whose oscilla 75 designate theV carrier frequency, which, in this
tion frequency fi2 is Ysome multiple of,- that of the
5
6
case, should preferably be greater than one mega
cycle.
carrier frequency by either amplitude, frequency,
,
or phase modulation. Under these conditions the
number of permutations is nine, so that nine dif
ferent communication systems result. This mayV
Referring to Fig. 2A, which shows a block dia
gram of the transmitter, the microphone 22 picks
up the speech sounds which it is desired to trans
mit. The microphone connects to the amplifier
- be seen from the following table.
modulator 23, which ñrst suitably ampliñes the
signal frequency and then is employed to modu
I
late the intermediate-modulating frequency fr
produced by the intermediate-frequency oscilla
Method by
sgr
which interme
modulate
g.
.
s Inter“
diete-modulaff
ing frequency
lgîliegläe'nlllìglê'
modulates the
g eq
y carrier frequency
tor 24. In consequence, the resulting output is
comprised of the intermediate modulating fre
quency fr in conjunction with the sum and dif
Amlliìlitude
o.
Do.
ference sideband frequencies due to the signal
frequency fs. This resulting output then goes to 15
IAmplitude
requency
Phase
Frequency
O.
the amplifier-modulator 25, where, after suitable
âmplitude
v
IeqlleIlCy
Do.
amplification, it is used to modulate the carrier
frequency oscillator 2B which is oscillating at a
frequency fc. As a result there is obtained an
output which is comprised of the carrier fre
L
Phase
Phase
Do.
Amplitude
Frequency
Do.
Phase
In a similar manner, when two intermediate
quency in combination with the sum and differ
ence sideband frequencies due to the complex of
the signal frequency and the intermediate-modu
modulating frequencies are employed, it will be
seen that: (1) II‘he si-gnals may either amplitude
modulate, frequency-modulate, or phase-modu
late the ñrst intermediate-modulating frequency;
(2) the first intermediate modulating frequency
may either amplitude-modulate, frequency-mod
lating frequency. After suitable amplification,
if desired, the doubly modulated carrier is radi
ated into space by means of the antenna 21.
At the receiver, as shown in Fig. 2B, the doubly
modulated carrier impinges upon antenna 28 and
ulate, or phase-modulate the second interme
is then amplified by amplifier 29. The output of
diate-modulating frequency, and (3) the second
amplifier 2S consists of the doubly-modulated `
carrier frequency and this is fed to the demodu
lator 30 which removes the carrier frequency and
intermediate-modulating frequency may either
amplitude-modulate, frequency-modulate, or
phase-modulate the carrier frequency. Accord
leaves only the signal-modulated intermediate
modulating frequency. This, in turn, is ampli
twenty-seven, it is seen that twenty-seven differ- ~
fied by amplifier 3| and is then fed to the de
modulator 32 which removes the intermediate
when two intermediate modulating frequencies
ingly, since the number of permutations lis
ent possible communication systems are possible
modulating frequency and leaves only the origi
nal signal frequency fs. After suitable amplifica
are utilized.
tion by means of amplifier 33 the resulting sig
nal frequency may be used to actuate a loud
ing frequencies are employed, the resulting num
ber of different communication systems is eighty
v
Similarly, when three intermediate-modulat
speaker.
one.
In general, when n intermediate-modulating
frequencies are employed the resulting number
of different communication systems is 30H1).
Since all of these different systems may be
t’ simultaneously employed, the total number N of
It is therefore seen that even when using such
a simple set-up as the one just described, a con
siderable degree of secrecy of message communi
cation may be obtained. For, if in the attempt to
intercept a message from the transmitter of Fig.
2B, an ordinary receiver were tuned to the carrier
frequency fc, nothing would be heard for the re
sulting demodulated frequency would be the in
different communication systems, and including
the conventional single modulation, which result
is given by the expression -
termediate-modulating frequency fr, and since
N=31+32+33+341 . _ _ 3(1L-l-l)
this was chosen to be about 100,000 cycles it is
beyond the audible frequency range and would
not, therefore, be heard. Only a receiver which
where n represents the number of intermediate
modulating frequencies. It is readily seen, there
doubly demodulates the doubly-modulated car
rier would be capable of properly receiving the
transmitted message.
fore, that the number of different communica
tion systems which become available increases
' very rapidly as the number of intermediate
modulating frequencies is increased. The rapid
ity with which different communication systems
become available is shown by the following chart.
In a similar manner, two intermediate-modu
lating frequencies may be employed to obtain a
triply-modulated carrier, thereby making it still
more diñîcult for the uninformed to intercept the GO
transmitted message. It is unnecessary to de
scribe such a system at this point, as this type
will later be used when the description of super
imposed modulation as used in conjunction with
multiple modulation is described.
At this point it will be well to examine the num
ber of different communication systems which are
possible as a result of the employment of multi
ple modulation.
When only one intermediate modulating fre
quency is employed it will be seen that: (1) The
Number of
available com
frequencies
systems
modulating
munication
0
1
2
3
4
3
12
39
120
363
5
ad infinitum
1, 092
ad infinitum
This enormous number of possible communi
cation systems is to be contrasted with the small
signals may modulate the intermediate-modulat
ing frequency by means either of amplitude, fre
quency, or phase modulation, and (2) the inter
mediate-modulating frequency can modulate the.
Number of
intermediate-
num-ber, namely three, which have hitherto been
75
available.
It is well to remember, however, that while the
w
i
3B; Considering. the first ofi these receivers, an
tenna 43 connects to amplifier 49 which amplifies
the carrier frequency. Afterv suitable amplifica
tion the complex signal is demodulated by de
modulator` 50",. thereby eliminating the carrier.'
The: output' of the demodulator willi contain all
employment'of an ever-increasing.` number ofi in'
termediate-modulating frequencies, and conse;
quently an ever-increasing number of different
communication systems, is theoretically capable
of indefinite extensionr there are, nevertheless,
practical limitations. Which..mitigate against such
indefinite extension. This practical limitation is
dependent upon the amountv of frequency band
width available, for, asthe‘number ofV intermedi
ate modulating frequencies ar‘eiincreased, so, like
wise, is the necessity for an increased frequency
band-width.
of the intermediate-modulating frequencies and'
their accompanying modulations. Accordingly;
a band-pass-ñlter 5i isinserted-in the» output cir‘
This band-pass ñlt'er
should beV operative at frequency fm, namely, at>
the frequency of the intermediate-modulating
oscillator 361 of the‘transmitter, and' it shouldï have
a'Í pass-band suflifciently Wide as to pass' the origi
inalï` signals of frequency fsA without undue' at- Y
tenuation. The output ofthe band-pass- filter
10 cuit. of’ demodulator 50.
Consequently, as more and more
intermediate-modulating frequencies are em
ployed the higher must the frequency of the car
rier become: in. order to maintain the frequency
band-width required at some given percentage of
the carrier frequency».
The intermediate-modulating frequency f1 is
not restricted toV any single frequency and may
Will' then contain intermediate-modulatingi fre
quency‘ fm- which has been modulated byî the
original signal frequency fsa. This is-then- am
p‘liñed' by amplifier 52- and then demod'ulatedí by
assume» various values, such as ffl, frz, frs», etc. 20 demodulator 534 so that the intermediate-modu
for any- given carrier frequency- f¢,.the same
lating frequency fla» is» removed. The> remaining
(or different) station may employy the intermedi
signalv frequency fs». is thenA amplified by ampli
ate-modulating frequencies- frl, frz, T13, etc., to
fier Sli, the output of whichY goes to` any suitableI
modulate the carrier. Since, in this event, band
device, as for example, a loud speaker or ear»
pass filters would be employed .to prevent any 25
phones;
interaction or interference. of the various inter
The operation cf the second- receiver is similar
mediate-modulating frequencies, it is seen that
to that just described. Antenna 55 receivesthe
the-«simultaneous- transmission of diverse signals
complex of’ signals radiated by transmitting an
may be transmitted- and received although but a
tenna 41 and this is fed tothe amplifier 56- which
30
single given carrier frequency is employed.
amplifies at the carrier frequency, after> which
A typicalV example.V of a transmitter which en
demodulator 51 removes the carrierY frequency.
ables the simultaneous- transmission of different
Since in this case it is desired'Y to receive the sig
signals when. but a single` carrier frequency is
nal frequency fsa the band-pass filter-5B' operates
employed is illustrated. in Fig. 3A. For simplicity
of> description only one intermediate-modulating> 35 at' frequency fm corresponding to frequency fm
of' oscillator 40 in thetransmitter.
frequency is used, as the extension of the-method.
Itis now possible‘to' examine how this'neW com
so asi to employ twoor. more intermediate-modu
munication system may be utilized so that the
lating, frequencies is` obvious. The microphone
regular
transmission ofv unimportant’ signals
34 picks up the speechV` signals. fs». at point A and
which employv the customary direct modulation
these are fed to the amplifier-modulator 35. The 4.0 may be simultaneously transmitted in conjunction
intermediate-modulating oscillator 36, whose os
with multiply-modulated signals containing the
cillation> frequency fm may, for example, be
essential information, in order to deceive- any
100,000 cycles, is modulated» by amplifier-modu-`
third party who may
the attempt' to> inter
lator 35. This modulated output then goes to
cept. the desired signals'. Atypical transmitter'
for. performing. this function is shown in Fig. 4A.
amplifier-modulator 31, which', in turn, modulates
the-carrier frequency oscillator'ßt. The doubly
modulatedwave- is thenfedinto the' antenna 41.
The desired signals fs are picked up by micro
In a similar manner, microphone 33- picks up
the speech signals fsB at point B and are then
1D', and' are then employed' to modulate theinter
phone ES', are' amplified' by ampliñ'er-mod'ulatorv
mediate-modulating frequency oscillator 1|'. The
frequency of' oscillation fr of the intermediate
modulating frequency oscillator 1|' may be any
suitable value, as. for example,> 100,000 cycles..
suitably amplified` by means of amplifier-modu
lator 39. The intermediate-modulating oscillator
has a frequency fm which is different from that
of intermediate-modulating oscillator 36, and it
The' modulated' output of intermediate-modulat'- ,
may be assumed, for example, that the inter
ing frequency oscillator 1'I‘ is fed'to' the. amplifier
modulator 12, which latter is> used" to modulate
mediate-modulatingv frequency fm is 200,000
cycles. Amplifier-modulator'then causes this- re
sulting. signal to` modulate. the' carrier frequency
oscillator.y
The microphone 42, the amplifier-modulator
43, the intermediate-modulating oscillator All,
and `the amplifier-modulator 45 operate in a
similar manner. Again the' frequency fic of in
the-carrier’frequency oscillator 13, and these sig
nals are radiated' into" space via antenna 16. Si
GO
multaneously with the' preceding, the falsesignals
Fs are rpicked'up by’ microphone 14', are amplified
bythe amplifier-modulator 15*y which latter also
modulates the` carrier frequency oscillator 1.3',~
termediate-modulating oscillator Ml is different
from that of the intermediate-modulating oscil
lators 36 and 40, so'that, for example, the oscilla
tion frequency fic of intermediate-modulating
oscillator 44 may be. 300,000 cycles.
. after which these false signals are. also’ radiated
It is, of course,.not necessary that the single
carrier frequency oscillator 43 be employed. In
ff.- Will receive only the false signals since itwill
be unresponsive tov the intermediate-modulating
frequency fr.'
stead, separate carrier frequency oscillators may
be used; the carrier frequencies of the separate
int'o‘sp'ace via the antenna 161.
It is therefore seen thatthe radiati'ons'em’ana‘t
ingfrorrrantenna'16` consist of‘the' desired'Í signals
andJ the; false signals; A> conventional receiver'
which is tuned to` receive the carrier frequency
In" order. to 'receive' the, desired ‘signals Yav receiver
oscillators being the same or‘diñerent'as desired.
Returning tothe preceding case, the complex
of Waves radiated by transmitting antenna. 41
of the type shown in FigAB‘ may be employed.
Antenna 11 picks up> the signal" radiated from‘
arepicked upby» antennas d'8, 55, and 62 of`Fig.
antenna- 16'.
This doubly-modulatecl-- signal is“
`
9
2,407,308
amplified by amplifier 78. The demodulator 79
removes the carrier frequency so that the output
of demodulator 'I9 contains the desired signal
modulated intermediate-modulating frequency
and the false signals.
The band-pass filter 89
permits only the signal-modulated intermediate
modulating frequency to pass through, so that
the output of band-pass filter Già does not contain
the false signals. After further amplification by
means of amplifier SI the signal-modulated inter
lator 82 which removes the intermediate-modu
lating frequency and leaves only the original de
sired signals. After further amplification by am
pliñer 89 the desired signals may be utilized to
actuate any suitable device, as, for example, a
loudspeaker or earphones.
ri‘Ühe signaling system just described is not lim
ited merely to the use of a single intermediate
modulating frequency, but may employ multiple- f
modulation using any number of intermediate
modulating frequencies, as desired.
the separately scrambled portions of the scram
bled signals modulate difierent intermediate
modulating frequencies. One of the manifold of
transmitters for accomplishing this purpose is
shown in Fig. 5A. The desired signal fs is picked
up by microphone 34, these signals then being
suitably amplified by means of amplifier 85.
From here the signals go to a Scrambler 86 which
breaks the signals up in any desired manner. One
portion of these scrambled signals feeds into the
amplifier-modulator 8l while the other portion of
these scrambled signals feeds into the amplifier
modulator 89. That portion which Went to am
plifier-modulator 81 is utilized to modulate the
first intermediate-modulating frequency oscillator
88, the output of which also goes to amplifier
modulator 89. Amplifier-modulator 89 then mod
ulates the second intermediate-modulating fre
quency oscillator 90. In other Words, the second
intermediate-modulating frequency oscillator 90
so that the second intermediate-modulating fre
quency is removed. The output of demodulator
líiâ‘ then goes to amplifier i?I, as did also one
portion of the desorambled signals coming from
descrambler 98. After suitable amplification by
amplifier I EI, demodulator IGZ removes the first
intermediate-modulating frequency, so that the
l() original signal now appears in the output of the
mediate-modulating frequency goes to demodu
There will now be described a typical method
whereby the desired signals are scrambled so that
flcation by means of amplifier 99 the doubly-mod
ulated portion is demodulated by demodulator |09,
demodulator. After suitable amplification by
means of amplifier IGS, the output of this ampli
îier may be utilized to aetuate any suitable device,
such as, for example, a loudspeaker or earphones.
The principle herein described is not limited in
its scope merely to radio transmission and recep
tion, for the principle of multiple-modulation may
be utilized in conjunction with supersonic signal
ing, to Wired Wireless, as well as to signaling by
means of other non-radio electromagnetic radia
tions, such as light-beam signaling, infrared sig
naling, and ultraviolet signaling.
Thus, in supersonic signaling, if IU in Fig. 1A,
27 in Fig. 2A, s1 in Fig. 3A, 'I6 in Fig. 4A, and 94
in Fig. 5A represent supersonic output sources,
the transmitters described in these various fig
ures may be employed to transmit multiply
modulated supersonic waves. Similarly, if I I in
Fig. 1B, 28 in Fig. 2B, 48, 55, and 62 in Fig. 3B,
'I1 in Fig. 4B, and 95 in Fig. 5B consist of super
sonic pickup devices, the various receivers de
scribed in these various figures may be employed
to receive multiply-modulated supersonic waves.
In a similar manner, a third party who at
tempted to intercept the signals of multiply
modulated light-beam, infrared beams, or'ultra
violet beams would receive the false transmis
sions if such were transmitted, but would not,
for the reasons already given, be able to intercept
40 the real signals which it Was desired to transmit.
The principle herein described, together with
the various systems evolving from this principle
is not, of course, limited in scope to the double
sideband transmissions which were used for illus
is modulated both by a portion of the scrambled 45 trative purposes only, but may utilize the various
signals and by the signal-modulated first inter
other forms of transmission technique as, for
mediate-modulating frequency. The output of
oscillator 9€! consisting of the superimposed mod
ulations then goes to amplifier-modulator 9|,
which latter modulates the carrier frequency
oscillator 92. After further amplification, if de
sired, by means of amplifier 93 the scrambled
complex of triply-modulated and doubly-modu
lated Waves are radiated into space by means of
antenna 94. Although for the sake of simplicity
it has not been shown, it is obvious that the sys
tem just described can be used in conjunction
With the transmission of false signals.
The reconversion of the original desired signals
example, single-sideband transmission, asym
metric-sideband transmission, suppression of the
carrier at the transmitter, as Well as the other
transmission techniques known to the art.
We claim:
1. A radio signaling system including a trans
mitter and a receiver, and in which the trans
mitter is provided with a pickup device and a
carrier frequency oscillator, and interposed mod
ulators and companion oscillators employing am
plitude, phase, and frequency modulations; and
in which the receiver is provided with a receiving
element and a translating device, and interposed
is accomplished by means of a receiver of the 60 modulators and oscillators for receiving from the
type shown in Fig. 5B. Antenna 95 picks up the
compleXly-modulated carrier which is then am
plified by means of amplifier 96. The process of
demodulation by means of demodulator 91 re
receiving element such amplitude, phase, and
frequency modulations as originated in the trans
mitter and delivering same to the translating
element.
moves the carrier, the output of the demodulator 65
2. A radio signaling system as claimed in claim
then going to the descrambler 98. Descrambler
l, wherein the number of oscillators and their
98 is arranged to act in synchronism with the
companion amplitude, phase, and frequency
Scrambler 86 of the transmitter, and is so ad
modulators are arrangeable in a selected se
justed that the doubly-modulated portion goes
quence.
to amplifier 99, While the single-modulated por 70
ROBERT LORENZEN.
tion goes to amplifier IUI. After suitable ampli
FELIX SPIEGEL.
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