US1917394A - Frequency modulation - Google Patents

Frequency modulation Download PDF

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Publication number
US1917394A
US1917394A US466955A US46695530A US1917394A US 1917394 A US1917394 A US 1917394A US 466955 A US466955 A US 466955A US 46695530 A US46695530 A US 46695530A US 1917394 A US1917394 A US 1917394A
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US
United States
Prior art keywords
resistance
tube
frequency
capacity
anode
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
US466955A
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English (en)
Inventor
Walter Van B Roberts
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 to BE381244D priority Critical patent/BE381244A/xx
Priority to NL35347D priority patent/NL35347C/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US466955A priority patent/US1917394A/en
Priority to GB19902/31A priority patent/GB369112A/en
Application granted granted Critical
Publication of US1917394A publication Critical patent/US1917394A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H03C3/14—Angle modulation by means of variable impedance by means of a variable reactive element simulated by circuit comprising active element with at least three electrodes, e.g. reactance-tube circuit

Definitions

  • an electron discharge device has, in its anode circuit, a resistance, it will be found that the input circuit thereof oifers a capaci-v tive reactance, variable with variations in the resistance. More broadly, the combination of the device and resistance may be considered a network, and int r-electrode capacity of the tube furnishing capacity and, the external resistance of the tube, resistance.
  • anetwork including a resistance and a capacity to. the frequency control circuit of a source of oscillations.
  • the effective capacity thereof is varied which in turn varies the resonant frequency of the control circuit and hence the frequency of oscillations generated.
  • the external resistance may simply be a microphone which is varied in value according to modulation energy, but preferably, I make the external resistance in the form of an auxiliary electron discharge device whose internal impedance or resistance is varied according to modulating potentials applied to a control electrode thereof.
  • Figure 1 diagrammatically indicates an electron discharge device having in its anode circuit a variable resistance and is given in 1930.
  • Figure 2 illustrates one form of my invention wherein a microphone is used as an anode resistance
  • FIG. 3 illustrates a preferred form of my invention.
  • FIG 1 I have illustrated an electron discharge device or vacuum tube 2, having a cathode or filament 4, control electrode or grid 6 and anode or plate 8.
  • the interelectrode capacity of the tube has been indicated diagrammatically by the dotted line capacity 10.
  • the output circuit or inthe anode circuit of the device 2 there is placed a variable resistance 12.
  • the input impedance across terminals 14 will be capacitive in nature. It will be found that by variation of resistance 12, the fictitious capacity across terminals 1e will vary.
  • the output of the oscillator 18 may, of course, be fed to a power amplifier 24 and then supplied to any desired utilization or output circuit 26.
  • the external resistance of electron discharge device 2 whose in put terminals, and consequently whose fictitious input capacity reactance, is paralleled with a tunable frequency control circuit 16 for regeneratively connected oscillator 28, takes the form of an auxiliary electron discharge device or vacuum tube 30.
  • the internal impedance or resistance of the device is varied as shown by applying modulation potentials to the control electrode 32 thereof, either voice energy by means of a microoil:
  • the frequency of the control circuit 16 is varied by variation of the resistance of the network formed by the ca pacity of tube 2, augmented if desired by condenser 39, together with the resistance of tube 30.
  • the resulting frequency modulated energy generated by oscillator 28 is amplified with asuitable power amplifier 40 and may be radiated by a suit-able radiating antenna 41.
  • a, C R and R may be so chosen that a given change (5R produced by the modulating voltage will produce a desired change (Z0 and hence a desired amount of change in frequency.
  • a thermionic oscillator comprising, an electron discharge tube and a frequency determining network, said oscillator generating a frequency depending in part upon the capacity between two points in said network, a second thermionic tube having an anode, cathode, an anode cathode circuit including resistance, a control electrode and a capacity between said anode and said control electrode, whereby the apparent capacity between the control grid and cathode of said tube depends upon the resistance in circuit between the anode and cathode of said tube, means for connecting the grid and cathode of said tube to said points in said network of said oscillator, a circuit for varying the resistance in the anode circuit of said second named tube comprising, a thermionic tube having its cathode connected to the anode of said second named tube and its anode connected to the cathode of said second named tube, and means for varying the anode to cathode impedance of said last named tube comprising, a source of modulating potential having one

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  • Transmitters (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
US466955A 1930-07-10 1930-07-10 Frequency modulation Expired - Lifetime US1917394A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE381244D BE381244A (de) 1930-07-10
NL35347D NL35347C (de) 1930-07-10
US466955A US1917394A (en) 1930-07-10 1930-07-10 Frequency modulation
GB19902/31A GB369112A (en) 1930-07-10 1931-07-10 Improvements in or relating to modulating systems for electric oscillations

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US466955A US1917394A (en) 1930-07-10 1930-07-10 Frequency modulation

Publications (1)

Publication Number Publication Date
US1917394A true US1917394A (en) 1933-07-11

Family

ID=23853719

Family Applications (1)

Application Number Title Priority Date Filing Date
US466955A Expired - Lifetime US1917394A (en) 1930-07-10 1930-07-10 Frequency modulation

Country Status (4)

Country Link
US (1) US1917394A (de)
BE (1) BE381244A (de)
GB (1) GB369112A (de)
NL (1) NL35347C (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473556A (en) * 1943-03-15 1949-06-21 Carl A Wiley Device for controlling oscillating circuits
US2590282A (en) * 1947-11-08 1952-03-25 Stromberg Carlson Co Variable impedance device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473556A (en) * 1943-03-15 1949-06-21 Carl A Wiley Device for controlling oscillating circuits
US2590282A (en) * 1947-11-08 1952-03-25 Stromberg Carlson Co Variable impedance device

Also Published As

Publication number Publication date
GB369112A (en) 1932-03-17
NL35347C (de)
BE381244A (de)

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