US2077223A - Modulation system - Google Patents

Modulation system Download PDF

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Publication number
US2077223A
US2077223A US21343A US2134335A US2077223A US 2077223 A US2077223 A US 2077223A US 21343 A US21343 A US 21343A US 2134335 A US2134335 A US 2134335A US 2077223 A US2077223 A US 2077223A
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US
United States
Prior art keywords
line
wave
tube
frequency
phase
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
US21343A
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English (en)
Inventor
Murray G Crosby
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.)
RCA Corp
Original Assignee
RCA Corp
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 claimed from US563725A external-priority patent/US2033231A/en
Priority to GB24323/32A priority Critical patent/GB406674A/en
Priority to DER85927D priority patent/DE626359C/de
Application filed by RCA Corp filed Critical RCA Corp
Priority to US21343A priority patent/US2077223A/en
Application granted granted Critical
Publication of US2077223A publication Critical patent/US2077223A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/10—Angle modulation by means of variable impedance
    • H03C3/12—Angle modulation by means of variable impedance by means of a variable reactive element
    • H03C3/18—Angle modulation by means of variable impedance by means of a variable reactive element the element being a current-dependent inductor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/10—Angle modulation by means of variable impedance
    • H03C3/12—Angle modulation by means of variable impedance by means of a variable reactive element
    • H03C3/20—Angle modulation by means of variable impedance by means of a variable reactive element the element being a voltage-dependent capacitor
    • 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
    • H03C3/26—Angle modulation by means of variable impedance by means of a variable resistive element, e.g. tube comprising two elements controlled in push-pull by modulating signal

Definitions

  • phase modulation has been accomplished by somewhat complicated circuit arrangements which are inserted in the transmitting, ap-
  • a primary object of this invention is to secure an improvement'in the method of and apparatus for modulating electrical waves.
  • a more specific object is to provide; a simple and efiicient phase modulation arrangement which 30 may 'be connected to any existing transmitter with very few changes.
  • these objects are attained by utilizing capacitive and inductive couplings between the l modulating device and the output of the carrier current amplifying apparatus.
  • these couplings may take the characteristics of a transmission line over which the wave energy to be phase modulated is propa 40 gated. Varying the values of either type of reactance in the line varies the wave propagation and consequently its phase.
  • FIG. 1 is a schematic diagram of a coinplete 50 transmitting system employing an artificial line.
  • Figs. 2, -3 and 4 are views illustrating various 65 specific circuit schemes for connecting the artiflcial line of Fig. 1 to the other portions of the system.
  • Fig. 1 illustrates a transmitting system adapted for phase modulation wherein the distributed constants of an artificial-line are varied in accordance with the signal wave.
  • a source of wave energy l of any nature such as, for example, a
  • crystal or long line control generator is coupled byway of a transmission circuit included in the rectangle A to a load circut of any nature shown for'purposes of example as an antenna.
  • a limiting device and an amp1iiier and a frequency multiplier may, if desired, be interposed between the line included in A and the output circult or the utilization point.
  • An artificial line shown in box A is connected to the source l by leads a and b.
  • the output end of the transmission line 20 is coupled by leads d and e to the load circuit directly or by way of said limiter, power amplifier and frequency multiplier.
  • Elements of the line are also connected by induct-, ances 2
  • glow discharge tubes I9 are utilized as a variable condenser and form part of the distributed capacity of the line.
  • These tubes l9 may be neon tubes, 7 cathode ray tubes or any suitable type of tube wherein an electron stream may be varied to vary the capacity between the electrodes of' the tubes and the metallic plate intermediate said electrodes. With no current through the tube the capacity of the tube will only consist of the capacity between the electrodes and the metallic plate.
  • the application'of a potential between the electrodes of the tube will cause a current to flow between the electrodes and a glow to strike which will, in turn, act as a conducting material between the electrodes.
  • a variation of thepotential across the tube will vary the glow within the tube with a consequent variation in capacity of the tube.
  • the impedance of the plate circuit of tube I I may I be controlled in any manner as. for example, by
  • One advantage of this arrangement is that the length ofv the line may be increased to increase the amount of phase deviation with signal, thus obtaining a decrease in the percentage of variation of the variable distributed constants and consequently obtaining a more linear modulation.
  • Any amplitude modulation caused in this circuit which might be undesirable may be removed in the system by employing limiters or over-loaded amplifiers whose output is limited to a definite value regardless of how much the input is increased.
  • An ordinary vacuum tube amplifier will serve this purpose if it is over-loaded in such manner that its output does not increase in proportion to its input.
  • frequency multipliers may be used to multiply the phase displacement of the modulated wave.
  • Another advantage of this particular arrangement is that an increase in phase deviation may be obtained by lengthening the artificial line. In such case, frequency multiplication will not be required.
  • Figs. 2, 3 and 4 illustrate different modulator units which may be employed to replace the apparatus'in box A of Fig. 1 in the complete transmitting system.
  • in the form of a variable condenser within which an artificial line is helically wound. If desired this line may be wound around the outside of the tube in very close proximity to the tube. The capacity of the line to ground is varied by changing the glow tube current, thus causing phase modulation of the carrier current impressed on the artificial line.
  • the effective inductance per un length of the artificial line is modulated by modulating the plate impedance shunted across the inductances 22, 22 which are coupled to the artlficial line at various points. In this manner the velocity of the carrier wave propagated along the artificial line is varied in accordance with the variation of the signal wave with a consequent modulation in phase of the carrier.
  • Fig. 4 is an arrangement whereby the plate impedance of the modulator tube isserially connected with the capacity of the line to ground. A variation of this plate impedance effectively varies the capacity of the line to ground.
  • the phase modulated wave energy produced in the modulators of the passing signals and appearing at d and e may be utilized directly or may be passed through an amplitude limiter of the overloaded tube type before using. If desired, the wave energy may be increased in frequency in I0 and also amplified before utilization.
  • a phase modulation system comprising a generator of constant frequency wave energy, an output circuit, a transmission line of considerable length as compared to the wave length of said wave energy comprising series inductanceand shunt capacity connected between said generator and said output circuit and means connected to said line for varying the effective electrical length thereof in response to signals to be transmitted.
  • a communication system for transmitting message waves comprising a source of wave energy of carrier wave frequency, an outputcircult for saidsystem, an artificial line of considerable length relative to the wave length of said waveenergy comprising impedance elements intermediate said source and'said output, and means for varying the effective length of said artificial line in accordance with said message wave whereby the phase of thecurrent passing through said lines is varied in accordance with the message waves transmitted.
  • a communication system for transmitting message waves comprising a source of wave energy of carrier wave frequency, an amplifying device, an artificial line of considerable length relative to the wave length of said wave energy consisting of inductive and capacitive elements intermediate said source and said device, and a modulating element for varying the impedance of either the inductive or capacitive elements of said line in accordance with said message wave whereby the phase of the current passing through said'line is varied in accordance with the message waves to be transmitted.
  • a device for relaying carrier frequency oscillations and for modulating the phase of the oscillations relayed at signal frequency comprising a source of carrier frequency oscillations, an in-.
  • ductance connected to one terminal of said source, a plurality" of reactance elements con: necting points on said inductance to the other terminal of said source, and means for varying the value of said reactances at signal frequency to-thereby vary the phase of theoscillations impressed on said inductance by said source comprising a thermionic tube having its input electrodes energized at signal frequency. and its anode electrode connected to said reactances.
  • a source of wave energy of substantially constant frequency a source of modulating potentials, a utilization circuit, an artificial line having distributed inductive reactance and distributed capacitive reactanceconnecting said source of wave energy to said utilization circuit, and an electron discharge amplifier having input electrodes coupled to said source of modulating potentials and having output electrodes connected in effect in shunt to at least one of said distributed reactances to vary the value thereof at the frequency of said modulating potentials, and thereby vary the ve-. locity of the wave energy along said line to said utilization circuit to thereby vary the phase of said energy reaching said utilization circuit at signal frequency.
  • phase modulation system as recited in v 9,077,988 claim 9 wherein said distributed minivan:
  • actance comprises'the capacity between the glow discharge betweenvthe electrodes of a discharge device and a plateadjacent'the path of said dis-- charge, and in-which the output electrodes of 10 able length 'as compared to the length of the with the modulating potentials.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplitude Modulation (AREA)
  • Transmitters (AREA)
  • Amplifiers (AREA)
US21343A 1931-09-19 1935-05-14 Modulation system Expired - Lifetime US2077223A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB24323/32A GB406674A (en) 1931-09-19 1932-08-31 Improvements in or relating to modulated carrier wave transmitting systems
DER85927D DE626359C (de) 1931-09-19 1932-09-17 Schaltung zur Phasenmodulation von Hochfrequenzstroemen
US21343A US2077223A (en) 1931-09-19 1935-05-14 Modulation system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US563725A US2033231A (en) 1931-09-19 1931-09-19 Modulation system
US21343A US2077223A (en) 1931-09-19 1935-05-14 Modulation system

Publications (1)

Publication Number Publication Date
US2077223A true US2077223A (en) 1937-04-13

Family

ID=26694574

Family Applications (1)

Application Number Title Priority Date Filing Date
US21343A Expired - Lifetime US2077223A (en) 1931-09-19 1935-05-14 Modulation system

Country Status (3)

Country Link
US (1) US2077223A (de)
DE (1) DE626359C (de)
GB (1) GB406674A (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2497605A (en) * 1946-05-23 1950-02-14 Hartford Nat Bank & Trust Comp Wave length modulating device
US2559023A (en) * 1949-02-21 1951-07-03 United Geophysical Company Inc Phase modulation
US2565231A (en) * 1947-01-04 1951-08-21 Hartford Nat Bank & Trust Co Variable artificial transmission line for effecting phase modulated oscillations
US2588551A (en) * 1949-02-21 1952-03-11 United Geophysical Company Inc Frequency modulation
US2652539A (en) * 1945-11-27 1953-09-15 Joseph W Kearney Method and means for wide band frequency modulation
US2656466A (en) * 1949-08-27 1953-10-20 Rca Corp Capacttor and circuit
US2666181A (en) * 1948-09-23 1954-01-12 Gen Electric Phase modulation system
US2679581A (en) * 1950-05-20 1954-05-25 Westinghouse Electric Corp Antenna tuning system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE911742C (de) * 1952-02-17 1954-05-20 Telefunken Gmbh Schaltungsanordnung zur AEnderung der Frequenz eines Oszillators
GB2225682A (en) * 1988-12-01 1990-06-06 Stc Plc Phase modulators

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2652539A (en) * 1945-11-27 1953-09-15 Joseph W Kearney Method and means for wide band frequency modulation
US2497605A (en) * 1946-05-23 1950-02-14 Hartford Nat Bank & Trust Comp Wave length modulating device
US2565231A (en) * 1947-01-04 1951-08-21 Hartford Nat Bank & Trust Co Variable artificial transmission line for effecting phase modulated oscillations
US2666181A (en) * 1948-09-23 1954-01-12 Gen Electric Phase modulation system
US2559023A (en) * 1949-02-21 1951-07-03 United Geophysical Company Inc Phase modulation
US2588551A (en) * 1949-02-21 1952-03-11 United Geophysical Company Inc Frequency modulation
US2656466A (en) * 1949-08-27 1953-10-20 Rca Corp Capacttor and circuit
US2679581A (en) * 1950-05-20 1954-05-25 Westinghouse Electric Corp Antenna tuning system

Also Published As

Publication number Publication date
DE626359C (de) 1936-02-28
GB406674A (en) 1934-02-28

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