US2474261A - Modulator - Google Patents

Modulator Download PDF

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Publication number
US2474261A
US2474261A US747214A US74721447A US2474261A US 2474261 A US2474261 A US 2474261A US 747214 A US747214 A US 747214A US 74721447 A US74721447 A US 74721447A US 2474261 A US2474261 A US 2474261A
Authority
US
United States
Prior art keywords
frequency
resistor
circuit
condenser
oscillator
Prior art date
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
Application number
US747214A
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English (en)
Inventor
Frank A Leibe
Benjamin B Mahler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Federal Telephone and Radio Corp
Original Assignee
Standard Telephone and Cables PLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to BE483044D priority Critical patent/BE483044A/xx
Priority to NL676711139A priority patent/NL140220B/xx
Priority to FR966138D priority patent/FR966138A/fr
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to US747214A priority patent/US2474261A/en
Application granted granted Critical
Publication of US2474261A publication Critical patent/US2474261A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/20—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator
    • H03B5/22—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator active element in amplifier being vacuum tube
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/10—Angle modulation by means of variable impedance
    • H03C3/24—Angle modulation by means of variable impedance by means of a variable resistive element, e.g. tube

Definitions

  • Our invention relates to modulators and is .particularly directed to means for frequency modulating oscillators of the phase-shift type.
  • the telegraphic signals are preferably applied, by keying, to a low frequency source, the marking and spacing impulses being characterized by different frequencies which are easily distinguished by filters at the receiving end.
  • the marking and spacing frequencies are preferably inthe audio range and for best results should be constant in amplitude and free of transients or key-clicks.
  • the desired low frequencies can not be easily generated with electronic oscillators having the usual inductance-capacitance tuning circuits. As the lower reaches of the audio frequency spectrum are entered, thetuning coils and condensers become prohibitively large and expensive. Beat frequency generators are complex and not particularly stable as to amplitude or frequency.
  • the object of our invention is an improved low frequency generator and means for modulating the frequency of the generator with telegraphic signals, the modulated output being constant in amplitude and free of transient currents.
  • Another object of our invention is a low frequency oscillator-modulator that is stable in frequency and amplitude and is relatively inexpensive.
  • the particular oscillator to which our inven tion is applied in this description comprises an amplifier tube l with anode 2, cathode 3 and control grid 4.
  • a tube with screen and suppressor grids may be used if desired.
  • the amplifier I is resistance coupled to amplifier tube 5.
  • the output circuit is coupled to the input circuit through a capacity-resistance network 6 with the required number of meshes to shift the anode voltage applied to the grid 180 electrical degrees.
  • the network shown comprises four meshes, each with a shunt resistor I and series capacitor 8. One resistor is tapped to divide the resistor into two portions, Ia and 1b.
  • the effective resistance between the ends of lb is made, I respectively, substantially zero or the full value of vice and a single-pole double-throw switch H is connected in circuit with the source to apply either a high positive or a high negative voltage to the cathode. magnetically controlled by a manual key or a teletype sender.
  • a condenser 12 is connected be tween the cathode and ground so that when the discharge device is made conductive, by applying a high negative voltage to the cathode, resistor, lb iseffectively short circuited for alternating voltages.
  • the transition between marking and space frequencies is made without disturbing transient currents.
  • a resistor l3 in series with the keying voltage and the condenser l2 comprise an RC time-constant circuit that will delay changes in potential of the cathode and will insure gradual changes in frequency. So that the charging and discharging pattern of condenser I! may be the same, to make marking and spacing signals symmetrical in shape, another electron discharge device M is placed across the condenser l2.
  • the polarity of the two space paths The switch armature may be as it does on negative battery thus assuring symmetrical modulating pulses and eliminating bias, and distortion, by the modulator circuit.
  • Adjustment of the amount of frequency shift is made possible by adjustments of resistors 1a and lb.
  • an oscillator circuit comprising a frequency determining impedance element, an arrangement for angle modulating said oscillator circuit with modulation signals from a source comprising an electron discharge device circuit, said electron discharge device circuit comprising a diode in series with a condenser, means for coupling said impedance element and said electron discharge device circuit in parallel, means for applying modulation signals across said condenser for controlling the conductance of said diode in accordance with the applied signals.
  • said impedance element is a resistor and said oscillator circuit comprises a.
  • resistance-capaci- In one oscillator we constructed, the amplifier tube i was a commercial pentode known as a GSJ'l, and the phase-shift network wascomposed of 200,000 ohm resistors and .0004 microfarad condensers. The mean frequency of oscillations was about 2375 cycles per second, and was made to shift about 100 cycles above and below this value for marking and spacing frequencies, respectively.
  • Discharge devices 9 and II were combined in one envelope, the double-diode known as the "6H6" being found well suited for the purpose. 130 volts positive and 130 volts negative at the terminals of direct current source l0 were found convenient to switch the diodes in normal keying, a conventional power rectifier and filter being used for this source.
  • the improved oscillator-modmator is relatively inexpensive to manufacture.
  • the frequency determining circuit of the oscillator is composed of resistors and condensers which, in the low frequency range mentioned, are small andv cost but a small fraction of the cost of the elements of any of the conventional inductance-capacity tuning circuits. Yet the frequency and amplitude stability of our oscillator is remarkably good.
  • the temperature coefilcient of resistance of resistors can be negligible, and fixed condensers can be sealed to be practically independent of temperature and humidity changes.
  • Our novel modulator, with its time delay features, goesfor smooth keying and in combination with the oscillator disclosed may be operated at high speeds without undesirable transients or distortion.
  • a signalling system comprising an oscillator having a frequency determining circuit, a resistor in said circuit, a diode and a condenser connected in series across said resistor, a source of positive and negative voltages connected to the junction of said diode and condenser, and a switch operable at signal frequency selectively applying said positive and negative voltages to said junction.
  • the signaling system defined in claim 1 further comprising a resistance element connect- -"ed in series between said junction and said source to voltage, a second diode and a second resistance element connected in series across said condentance across said regenerative circuit including said resistor.
  • prising means for coupling one end of said resistance to the plate electrode of said device.
  • said second discharge device circuit comprises a diode, means for coupling the plate electrode of said second device to said junction point and its cathode electrode through a resistance to the other end of said resistor.
  • said source comprises a source of positive and negative potentials, means for applying said positive and negative potentials across said condenser in accordance with the intelligence to be transmitted.
  • said last named apparatus comprises a resistor and switching means for applying said positive and negative potential through said last named resistor across said condenser.

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  • Oscillators With Electromechanical Resonators (AREA)
US747214A 1947-05-10 1947-05-10 Modulator Expired - Lifetime US2474261A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE483044D BE483044A (fi) 1947-05-10
NL676711139A NL140220B (nl) 1947-05-10 Werkwijze voor de vervaardiging van een voorwerp uit een met water verharde massa, en aldus verkregen voorwerp.
FR966138D FR966138A (fi) 1947-05-10
US747214A US2474261A (en) 1947-05-10 1947-05-10 Modulator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US747214A US2474261A (en) 1947-05-10 1947-05-10 Modulator

Publications (1)

Publication Number Publication Date
US2474261A true US2474261A (en) 1949-06-28

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Family Applications (1)

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US747214A Expired - Lifetime US2474261A (en) 1947-05-10 1947-05-10 Modulator

Country Status (4)

Country Link
US (1) US2474261A (fi)
BE (1) BE483044A (fi)
FR (1) FR966138A (fi)
NL (1) NL140220B (fi)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2610318A (en) * 1947-12-03 1952-09-09 Int Standard Electric Corp Electronic frequency modulator
US2636941A (en) * 1950-04-25 1953-04-28 Westinghouse Electric Corp Frequency shift keying circuits
US2667536A (en) * 1951-08-07 1954-01-26 Bell Telephone Labor Inc Carrier telegraph system
US2716218A (en) * 1952-06-06 1955-08-23 Rca Corp Frequency variation circuit
US2796523A (en) * 1953-09-10 1957-06-18 Vickers Electrical Co Ltd Control circuits for electric oscillators
US2802937A (en) * 1954-05-05 1957-08-13 Bell Telephone Labor Inc Teletypewriter station network including mobile station
DE971380C (de) * 1953-01-19 1959-01-22 Philips Nv Vorrichtung zum Erzeugen von mit einem Modulationssignal frequenzmodulierten Schwingungen
US2874216A (en) * 1953-10-27 1959-02-17 Gen Electric Automatic signal control system
US2906960A (en) * 1953-09-05 1959-09-29 Estey Organ Corp Electrical musical instrument with frequency divider circuit

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1831933A (en) * 1929-04-18 1931-11-17 Wired Radio Inc Frequency modulation system
US1950759A (en) * 1931-05-25 1934-03-13 Frederick E Terman Variable reactance circuit
US2382198A (en) * 1942-05-16 1945-08-14 Rca Corp Oscillator stabilizing circuit
US2394427A (en) * 1942-11-09 1946-02-05 Rca Corp Wave length modulation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1831933A (en) * 1929-04-18 1931-11-17 Wired Radio Inc Frequency modulation system
US1950759A (en) * 1931-05-25 1934-03-13 Frederick E Terman Variable reactance circuit
US2382198A (en) * 1942-05-16 1945-08-14 Rca Corp Oscillator stabilizing circuit
US2394427A (en) * 1942-11-09 1946-02-05 Rca Corp Wave length modulation

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2610318A (en) * 1947-12-03 1952-09-09 Int Standard Electric Corp Electronic frequency modulator
US2636941A (en) * 1950-04-25 1953-04-28 Westinghouse Electric Corp Frequency shift keying circuits
US2667536A (en) * 1951-08-07 1954-01-26 Bell Telephone Labor Inc Carrier telegraph system
US2716218A (en) * 1952-06-06 1955-08-23 Rca Corp Frequency variation circuit
DE971380C (de) * 1953-01-19 1959-01-22 Philips Nv Vorrichtung zum Erzeugen von mit einem Modulationssignal frequenzmodulierten Schwingungen
US2906960A (en) * 1953-09-05 1959-09-29 Estey Organ Corp Electrical musical instrument with frequency divider circuit
US2796523A (en) * 1953-09-10 1957-06-18 Vickers Electrical Co Ltd Control circuits for electric oscillators
US2874216A (en) * 1953-10-27 1959-02-17 Gen Electric Automatic signal control system
US2802937A (en) * 1954-05-05 1957-08-13 Bell Telephone Labor Inc Teletypewriter station network including mobile station

Also Published As

Publication number Publication date
FR966138A (fi) 1950-09-30
BE483044A (fi)
NL140220B (nl)

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