US1449372A - System of telephony - Google Patents

System of telephony Download PDF

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Publication number
US1449372A
US1449372A US64502A US6450215A US1449372A US 1449372 A US1449372 A US 1449372A US 64502 A US64502 A US 64502A US 6450215 A US6450215 A US 6450215A US 1449372 A US1449372 A US 1449372A
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United States
Prior art keywords
frequency
wave
component
waves
unmodulated
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US64502A
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English (en)
Inventor
Harold D Arnold
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AT&T Corp
Original Assignee
Western Electric Co Inc
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Filing date
Publication date
Application filed by Western Electric Co Inc filed Critical Western Electric Co Inc
Priority to US64502A priority Critical patent/US1449372A/en
Priority to CH104686D priority patent/CH104686A/de
Priority to DE1920353944D priority patent/DE353944C/de
Priority to CH96264D priority patent/CH96264A/fr
Priority to FR517685A priority patent/FR517685A/fr
Priority to GB18799/20A priority patent/GB146881A/en
Application granted granted Critical
Publication of US1449372A publication Critical patent/US1449372A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/52—Modulators in which carrier or one sideband is wholly or partially suppressed
    • H03C1/60—Modulators in which carrier or one sideband is wholly or partially suppressed with one sideband wholly or partially suppressed

Definitions

  • detecting devices are used. to respond to low frequency modulations only.
  • the carrier wave as is of frequency C, and the modulating Sig nal wave of frequency S the resultant modulated high frequency wave of a current of varying amplitude sent into the sending circuit can be resolved into three simple no sine waves of frequencies CS, C, C+S. 'These may be considered to be transmitted independently, and to recombine at the receiving station.
  • This is .the method which has heretofore been commonly followed, but 655 in this invention, as hereinafter disclosed,
  • the carrier wave When the carrier wave is not. being modulated, that is,-when signals are not being transmitted, an unmodulated current or frequency G flows in the sending circuit, and the power represented by this current is wasted as heat or radiation. Further, when signals are being transmitted, only,the first and third of the waves mentioned above contain the signal frequency, and hence in this case the wave of carrier frequency is of use only after it arrives at the receiving station Y and enters the detecting device. Since the power represented in the sending circuit by currents of frequency 0 may be several times that radiated in the other frequencies, the
  • this invention proposesto eliminate it from thesendingcircuit, and to add, at the 're-- ceiving station, a generator which'shall supply a wave of-this frequency to combine with the first and third of' the waves above mentioned, or either separately when they arrive at the receiving circult. Since only a very small part of the power radiated arriv'es at the receiving station, it is clear that the power output of this auxiliary generator need be but small (perhaps one millionth part of that of the sending generator), and there will result a decided gain in efiiciency.
  • FIG. 2 represent, respectively, af sending and a receiving station for radio telegraphy or telephony.
  • Fig. 1 which represents a form which may be taken by the transmitting station of this invention
  • .1 represents a high frequency generator of small power capacity, preferably an oscillating audion, such for example, as that described in the U. S. Patent No. 1,137,384 to E. H. C'olpitts.
  • transformer 3 its oscillations are impressed upon the input circuit of a modulator 5.
  • 2 represents a microphone circuit and 4 a transformer by means of which waves of signal frequency may also be impressed upon the input circuit of the modulator?
  • These oscillations of signal frequency are preferably of somewhat greater amplitude than those impressed upon the modulator 5' by the generator 1.
  • the amplifying powerof the device 5 is varied in accordance with the wave form of the telephonic currents in circuit 2, and there therefore appears in the output circuit of modulator 5 a modulated high frequency current.
  • Transformer 6 serves to impress these modulated high frequency oscillations upon a system of tuned circuits next to be described,
  • Th1s system of tuned circuits may also suppress one of the modulated components as described above.
  • This system of tuned circuits may be of any suitable form, and as shown here, consists of the resonant circuit 7 tuned to the carrier frequency and the pair of resonant circuits 8, one of which is tuned to'a frequency slightly above the carrier frequency and the other to a frequency slightly below it, while the combination of these two circuits in parallel offers an infinite impedance to currents of the carrier frequency.
  • the transmitting circuit 2 is not in operation, thecurrent in the outputcircuit of modulator 5 isof carrier frequency, and therefore no current appears in the primary of the transformer 9.
  • modulation is intended herein to define the variations of'the amplitude of oscillations of one frequency in accordance with a wave of lower requency.
  • modulation is intended to specify a change in either the amplitude or the frequency or both, of periodic disturbances occurring in any medium, at a desired relatively low rate. In one aspect it is a change at a relatively low rate in the energy variations of a relatively high frequency wave.
  • the term pure modulated wave is used to define a modulated wave in which there is present no component having the wave form and frequency of the unmodulated high frequency oscillations and in which the modulation is complete, in the sense that the modulation is effective throughout the entire cyclic period of the modulatin wave.
  • a high frequency wave for example of frequency 50,000
  • when modulated bymeans of a current of, say 1000 cycles per second is e uivalent to threesimple harmonic waves o frequencies 19,000, 50,000 and 51,000.
  • the wave of carrier frequency of constant amplitude, namely 50,000 is not concerned directly in the transmission of speech, and it is this wave which it is proposed to eliminate in this invention.
  • the tuned-circuit 8 would have a small impedance to waves of frequency 49,000 and 51,000 and a practically infinite impedance to waves of frequency 50,000.
  • Fig. 2 which represents a receiving system adapted for use in connect-ion with the transmitting system of Fig. 1, 15 represents anantenna and 16- a transformer by means of .which power is transferred from the antenna to a system of resonant circuits similar to that described in connection with Fig. 1.
  • Fig. 2 which represents a receiving system adapted for use in connect-ion with the transmitting system of Fig. 1
  • 15 represents anantenna and 16- a transformer by means of .which power is transferred from the antenna to a system of resonant circuits similar to that described in connection with Fig. 1.
  • 15 represents anantenna and 16- a transformer by means of .which power is transferred from the antenna to a system of resonant circuits similar to that described in connection with Fig. 1.
  • Transformer 19 communicates power from these tuned circuits tov 23.
  • oscillations of the carrier fre which may be similar to the oscillation generator 1 of Fig. 1, and is coupled to circuit 20 by transformer 25.
  • the power supplied by this oscillator 26 may obviously be very small compared to the power of the oscillations radiated at the sending station.
  • the method of signalling which comprises modulating a carrier frequency wave in accordance with a signal and subsequently suppressing the carrier frequency component of the resultant wave.
  • a transmitting station comprising a source of high frequency waves, a source of low frequency waves, a thermionic modulator upon whose'input circuit are impressed the Waves generated by said sources to produce a wave having an unmodulated component and side frequency components comprising respectively a wave of the frequency generated by said high frequency source and the combination frequencies of the waves from said high and low frequency sources, a tuned circuit whereby the unmodulated component is suppressed, a system of amplifiers, a sending antenna connected to said system of amplifiers, with a receiving station comprising an antenna, a tuned circuit, an auxiliary source of waves of frequency equal to that of the waves generated by said first mentioned source, and a detecting device acted upon by said received waves and by said auxiliary waves.
  • one branch of which is tuned to said unmodulated component and another branch of which is tuned to two frequencies, one higher and one lower than that of said component.
  • Signal transmitting means comprising a source of oscillations, means to modulate said oscillations in accordance with signals to produce a wave having an unmodulated component and side frequency components comprising respectively the oscillations of the fre uency generated by said source and the com ination frequencies of said oscillations and the signal waves, means to filter out the unmodulated component, and means to amplify the modulated oscillations passed by said filtering means.
  • the method of signaling which consists in transmitting high frequency carrier waves, whose amplitude is directly proportional to a low frequency signal wave, and combining therewith another wave.
  • the method of signaling which consists in transmitting high frequency carrier waves whose amplitude is directly proportional to a low frequency signal Wave, and combining therewith another wave of carrier frequency and constant amplitude.
  • the method of signaling which consists intransmitting, to the exclusion of other waves, a high frequency carrier wave whose amplitude is directly proportional to a low frequency signal wave, and combining therewith another wave of carrier frequency and constant amplitude.
  • means for producing a carrier wave component and a signal representing side band component and means for separating said components including a combination of condensive and inductive elements arranged to form a seriesresonant path for alternating currents of a frequency corresponding to one of said components and an parallel-resonant path for alternating currents of a frequency corresponding to the other of said components.
  • a source of waves comprising an. unmodulated carrier component and signal representing side band components and means providing high impedance for said unmodulated component and low impedance for said side band components comprising a branched circuit, one branch of which is resonant to one side bland and the other branch of which is resonant to the other side band.
  • a source of waves comprising an unmodulated carrier component and signal representing side band components and means providing high impedance for said unmodulated component and low impedance for said side band components comprising a branched circuit, one branch of which is resonant to one side band and the other branch of which is resonant to the other side band, said branches comprisinga loop whichis resonant to said unmodulated component.
  • a source of complex waves including components of desired frequencies and a component of an undesired frequency and means for separating said components, comprising a group of reactive elements arranged to form parallel paths for the passage. of electrical energy and comprising a series-resonant path for each of said desired frequencies and a parallelresonant path for said undesired frequency.
  • a source of complex waves having a component of a desired frequency and'a component having an undesired frequency and a circuit for passing the component of the said desired frequency and for suppressing the component of said undesired frequency, comprising a 100 circuit tuned to resonance with said undesired frequency and comprising two branch circuits, one of which is resonant at said desired frequency and the other of which is resonant at a frequency spaced from the undesired frequency an interval equal to that between said desired and undesired frequency andin the opposite direction.
  • means for producing a high frequency wave means for modulating said wave in accordance with a signal to give an unmodulated component and side frequency components, said means comprising a space discharge modulator, and means in addition to the modulating means for suppressing the unmodulated component of the modulated wave.
  • the method which consists in generating high frequency oscillations modulated in accordance with a signal wave to produce a wave having an unmodulated component and side frequency components, attenuating the unmodulated components of the current resulting from modulation, and amplifying the resultant current.
  • the method which consists in generating undamped high frequency oscillations modulated in accordance with a signal Wave to produce .a Wave having an unmodulated component and side frequency components. filtering out the unmodulated component thereof, and'amplifying and transmitting the resultant wave.

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  • Transmitters (AREA)
  • Interconnected Communication Systems, Intercoms, And Interphones (AREA)
US64502A 1915-12-01 1915-12-01 System of telephony Expired - Lifetime US1449372A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US64502A US1449372A (en) 1915-12-01 1915-12-01 System of telephony
CH104686D CH104686A (de) 1915-12-01 1917-06-04 Verfahren und Einrichtung zur elektrischen Fernverständigung.
DE1920353944D DE353944C (de) 1915-12-01 1920-05-23 Signalsystem
CH96264D CH96264A (fr) 1915-12-01 1920-06-21 Installation de signalisation par ondes porteuses modulées à haute fréquence.
FR517685A FR517685A (fr) 1915-12-01 1920-06-23 Système de signalisation utilisant des ondes porteuses modulées à haute fréquence
GB18799/20A GB146881A (en) 1915-12-01 1920-07-06 Improvements in wireless signalling systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US64502A US1449372A (en) 1915-12-01 1915-12-01 System of telephony

Publications (1)

Publication Number Publication Date
US1449372A true US1449372A (en) 1923-03-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
US64502A Expired - Lifetime US1449372A (en) 1915-12-01 1915-12-01 System of telephony

Country Status (5)

Country Link
US (1) US1449372A (fr)
CH (2) CH104686A (fr)
DE (1) DE353944C (fr)
FR (1) FR517685A (fr)
GB (1) GB146881A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2497592A (en) * 1947-11-13 1950-02-14 Lennart G Erickson Carrier terminal equipment
US2530614A (en) * 1943-10-21 1950-11-21 Hartford Nat Bank & Trust Co Transmitter and receiver for single-sideband signals
US2559390A (en) * 1947-07-03 1951-07-03 Gen Railway Signal Co Centralized traffic control system
US2699494A (en) * 1950-05-08 1955-01-11 Hartford Nat Bank & Trust Co Suppressed carrier single side band radio transmission system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2530614A (en) * 1943-10-21 1950-11-21 Hartford Nat Bank & Trust Co Transmitter and receiver for single-sideband signals
US2559390A (en) * 1947-07-03 1951-07-03 Gen Railway Signal Co Centralized traffic control system
US2497592A (en) * 1947-11-13 1950-02-14 Lennart G Erickson Carrier terminal equipment
US2699494A (en) * 1950-05-08 1955-01-11 Hartford Nat Bank & Trust Co Suppressed carrier single side band radio transmission system

Also Published As

Publication number Publication date
FR517685A (fr) 1921-05-10
CH104686A (de) 1924-05-16
DE353944C (de) 1922-05-30
CH96264A (fr) 1922-09-16
GB146881A (en) 1921-09-29

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