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Патент USA US2105809

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"J'Qäs, i938.
Filed Aug. l, 1936
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wrm». ,
Patented Jan. 18, 1938
~ 2,105,809 "
Í UNlTED STATES 'PATENT ol-‘l-‘lclsl->
Robert D. Duncan, Jr., East orange, N. J., as;
signor to Wired Radio, Inc., -New York, N. Y., a -
corporation of Delaware
Application _august 1, i936, sel-inl Nogjsaeos
2 claims’. (Cl. 179-15)
'I‘his invention pertains in general to the trans
_auxiliary high 4range carrier frequency which
nlission of programs and specifically relates to operates through means for producing 'the desired
such systems for transmitting programs in which lower frequencies for carrier replacement pur
_the-carrier frequency is substantially eliminated poses. 'This replacement carrier isvthen incor
5 'during transmission and replaced upon reception. ` porated with the received program energy to re- 5
The principal object of the invention con? place the suppressed carrier for audible reproduc
sists in providing a transmission system having tion of the transmitted program.
means' for impressing modulated carrier fre
Referring to the drawing in detail, there is pro
’ quency energy upon a transmission medium with
vided a commercial power transmission network I
l0 the carrier frequency itself substantially elimi
connected with power equipment 2. This power 10
nated; said energy being received at a remote equipment 2," may be located in the commercial
point with local replacement of the carrier ire
power substation 3. The lines I, equipment 2.
and sub-station _3 are indicative of a power trans
A. Vfurther object of the invention comprises ‘ mission network in general. In the present in
lo providing a suppressed carrier _transmission sys
tem in which an auxiliary higher ,carrierfre
quency is transmitted to the point of recep
tion for incorporation with the received energyfor carrier frequency replacement purposes.
stance, the lines I are of the three phase 60-cycle 15
alternating current type and operate through a
step down transformer 4 to supply commercial
voltages to the consumer’s local transmission cir
cuit 5.
These and other objects will be apparent from
the following, reference being >had to the accom
panying drawing which represents one embodi
cillator 8 develops high frequency oscillations of
a standard frequency, such as 13 kilocycles.- The
ment of the system of my invention.
*_ ,
My invention contemplates the provision of a
In accordance with the invention, a master os'- ' '20
' oscillator 8 may be of a. type known in the art,
such as a crystal controlled thermior'lic oscillator
transmission system for developing a plurality
circuit.- 'I'he output of the oscillator 8 is directedr ‘25
of related» carrier frequencies from a master os
to a harmonic generator 9 which develops, from
cillator. These carrier frequencies, having a
the master frequency, a plurality of harmonically
multiple relationship, are each subjected to in
dividual program modulation. Concomitantly,
30 each- of. the‘carrier frequencies is eliminated so'
that the energy impressed uponthe transmission
medium comprises program modulated’l carrier
related multiple frequencies. vFor example, these
' energy in the side band regions, the side band4
multiple frequencies may be 26, 39 and 52 kilo
cycles, respectively, and correspond to diüerent '30
program channels. These different carrier fre
quencies are respectively. directed to transmitters
III, II and I2.
The transmitters I0, ~II' and I2 each comprise
regions corresponding to the related carrier fre
,35 quencies being, of course, discretely situated along ~ known means for respectively producing ampliñed 35
the frequency spectrum 'to'produce independent three phase carrier frequency energy. 'I‘he high
frequency energy for each transmitter is modu
program channels; In. the- embodiment illus
trated, I employ _a commercial power network as lated in accordance with the individual source of
' the transmission medium, although the invention modulation" energy` associated with that trans-_40 ls not to be strictly limited thereto, since other _ mitter. _In addition, each carrier frequency it- ¿o
media may be employed` without departing from
the intended scope of the
ing out the invention, 'the
energy may be restricted
45 band of frequencies, when
inventiomv In carry
transmitted program
tobut a single side
self is eliminatedifrom the modulated carrier
energy so that the output at the transmitter com
prises three-phase modulated carrier-energy in
the side band „range with the carrier frequency
itself substantially eliminated.`
\ v. _
lin accordance with the invention',- means are`-> , The circuits for such transmission`\ equipment
provided for developing,-from the master oscilla
>are known in the art.> A' special form 'of such y
tor, an additional carrier frequency arranged'sub
stantially higher than those .of the program chan
carrier elimination and transmission circuits may
be seen in my copendinlg application, _Serial No.
50 nels. This high carrier frequency is then trans
40,526,'as well as in the copending applications 50 '
or E; A. Laport, serial No. 52,751; and serial No.
mitted over the transmission medium in an un
modulated condition. At the point _of reception, , 50,491. The harmonic generator als'ocom'prlses
the receiving equipment selectively receives any means knownfin the art, such as 'electron -tube
one of the program channels. At the same time, circuits of standard form, for producing such
' u
55 equipment _is provided for the reception of the harmonically related' carrier frequencies.
The outputs of"transmitters IIJ, II and I2 are
directed respectively through filters I4, I5 and I6.
ceiver 20. The circuits of the receiver 20 selec
tively receive the program modulated carrier fre
These filters limit the output of the transmitters
to discrete carrier frequency ranges comprising
the different program channels. The output cir
quency energy with the carrier frequency itself
suppressed while the output of amplifier 21 sup
plies this carrier frequency.- As a result, the re
cuits of filters I4, I5 and I6 are directed through
capacitive couplings to the lines I.
ceiver 20 replaces this carrier frequency as sup
plied from the amplifier 21 so that the desired
program can be intelligibly reproduced by the
A harmonic generator I1 is also connected with
the master oscillator 8 for developing high fre
10 quency oscillations within a range higher than
loud speaking device 2|.
In another arrangement of the system of the 10
invention, a frequency sub-divider of any type
might besubstituted for the multivibrator 25.
Again, a harmonic generator may be substituted
for the >iilter 26 for producing a selected _fre
quency vfrom the sub-divided frequency.
In another embodiment of the invention, the
harmonic generators 9 and I1 may be combined
in a single unit so that one harmonic generator
serves to produce the carrier frequencies `for the
transmitters III-I2, as well as the auxiliary car 20
the carrier frequencies `associated with the trans
mitters I0, II and> I2. For example, the har
monic generator I1 may develop a frequency of
the order of 78 kilocycles. In suitably amplified
15 form, the output of the harmonic generator I1
is directed through ñlter I8 which limits the
output of the harmonic generator I1 to the de
sired high frequency, such as '18 kilocycles. The
output of the filter I 8 is then directed through
capacitive couplings to the power lines I.
The consumer’s dwelling including the circuit rier frequency passed through filter I8.
5 is provided with a receiver 20 and loud speaker
Although I have .shown a preferred embodi
unit 2I for audibly reproducing the programs ment of my carrier supply system, it will be
transmitted over the lines I.l The receiver 20 understood that various changes can be made
25 embraces suitable selection, amplification and without-'departing from the intended scope of
detection circuits known in the art for repro Imy invention. Therefore, I do not desire to
ducing desired programs. 'I‘he circuits of re
limit myself to the foregoing except as may be
ceiver 20 include electron tubes energized through pointed out in the appended claims.
power connections 22 extending to the circuit 5.
What I claim as new and original and desire
30 The signal input circuit for the receiver 20 is to secure by United States Letters Patent is:
directed through capacitive couplings 23 and also
1. In a transmission system in which a plu
connected with the power circuit 5.
rality of modulated suppressed-carrier high
A further circuit is provided from the capacitive frequency bands and carrier replacement high
couplings 23 to direct signaling energy through frequency waves are transmitted to a receiving
a filter 24 >to a multivibrator 25. The filter point as discrete frequencies, receiving appara 35
24 comprises a selective circuit corresponding to
the ñlter I8 and restricted to the range of high
frequency auxiliary carrier such as 78 kilocycles
developedby the harmonic generator I1. The
40 multivibrator 25 comprises circuits known in the
art for producing a sub-multiple of the oscilla
tions of a given high frequency. In the present
instance, the multivibrator 25 produces a 13 kilo
cycle frequency which is the sixth sub-multiple of
45 the 78 kilocycle auxiliary carrier frequency, as
well as other frequencies which are harmonics
'I'he output of the multivibrator 25 is directed
tus comprising, a receiver selectively operable to
receive any one of said plurality of modulated
suppressed-carrier high-frequency bands, means
responsive to said replacement carrier waves for
supplying to said receiver any one of several re
placement carrier frequencies corresponding to
the carrier suppressed from said modulated high
frequency bands received by said receiver, and
common control means for operating said last
mentioned means and said receiver so that when 45
a particular modulation band is received by said
receiver, said last mentioned means operates to
supply thereto a corresponding replacement car
rier frequency for intelligibly reproducing the
desired modulation by said receiver.
quencies directed thereto from the multivibrator.
2. In a transmission system in which a plu
The circuits of the filter 26 are selectively ad-> rality of modulated suppressed-carrier high
f to a selective filter 26 having a circuit known in
50 the art for producing a selection among the fre
justable for passing any one of several harmonic
frequencies,.as for-example, 26 kilocycles, 39vkilo-l
55 cycles, or 52 kilocycles, it being remembered that,
in the present embodiment of, the invention, the
frequency bandsfand a carrier replacement wave
, are transmitted at different frequencies to a re
ceiving point, a receiver selectively operable to 55
receive any one of said plurality~ of modulated '
selection circuits of the receiver 20 are adjust
suppressed-carrier high-frequency bands, a re
able for the selective reception of carrier fre
placement carrier means for receiving said re
quency energy within similar ranges. Accord . placement wave and adapted to generate there
insly. a common control knob 28 is mechanically from a plurality of replacement carrier waves
connected with the adjustable _elements of the corresponding to the carriers suppressed from
selection circuits of receiver 2D and the adjust
said bands, and common control means for con
able elements of the circuits of the filter 26 so jointly operating said receiver to receive a se
that the output of the filter 26 always 'corre
lected band and said replacement means to sup
sponds in frequency with the selection of the ply thereto a corresponding carrier wave of the 65
receiver 20.
proper frequency for replacement purposes.
The output circuit of the filter 26 is directed
through an amplifier 21 and thence to the re
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