US2583138A - Frequency modulator - Google Patents

Frequency modulator Download PDF

Info

Publication number
US2583138A
US2583138A US718498A US71849846A US2583138A US 2583138 A US2583138 A US 2583138A US 718498 A US718498 A US 718498A US 71849846 A US71849846 A US 71849846A US 2583138 A US2583138 A US 2583138A
Authority
US
United States
Prior art keywords
network
frequency
crystal
generator
modulation
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
US718498A
Other languages
English (en)
Inventor
John M Carter
John R Boykin
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.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric 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 BE478223D priority Critical patent/BE478223A/xx
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US718498A priority patent/US2583138A/en
Application granted granted Critical
Publication of US2583138A publication Critical patent/US2583138A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H03C3/245—Angle modulation by means of variable impedance by means of a variable resistive element, e.g. tube by using semiconductor elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning

Definitions

  • Fichandler Patent 1,2,000,584.
  • Fichandler discloses. a system for producing freen myo u a e o ci at o s compr s ng a. fr quency-determining network, across which a variable resistance and ar actancere. conne te The co po en s. at he, ne we h and the. es anee and, r etanee a e.
  • W have found that a transmitter including the Fichandler system. has severa undes ra le features. Th output a tra sm tt s distorted. It is. marredby hum such asarises from undesired pulsations of a, (id-cycle, power supply and by other sounds notintrodimed by the modulating source, Amplitude modulations are also at times present in the outp t;
  • Another object of our invention is to provide a f qu cy-modulation. system which shall pro prise s na substantially ree oi alternati s urren hum.
  • a fur her obj ct f our invention is to prov de a irequen y-modu ati n s in wh ch ex raneous ounds, are substantially suppr ss d.
  • St ll. anoth r objec r our invention is to provide a frequency-modulation syst m which. sha pr prise si als substantially fr e oi amp tu e modul tions.
  • Fichandlers resistance tube The interelectrode capacity of Fichandlers resistance tube is substantial, as is, also the capacity to ground of the, electrodes. These capacities introduce distortion into, the modulations impressed on the frequency-determining network. The amplitude of the distortions is small, but the distortionsare highly amplified by the frequency multiplication and deteriorate the out,-
  • variable resistance tube (3.4., Fig, 5), haying substantial anode grid capacity, p ovides a r at y ow mped c f e a nathe enerative e f c p u d by the feedback amplified by multiplication also dete o ates th outpu I c r anc i h. r n n ion we pro: e a i eu n y-moduiatisn network c mp sing a crystal of thetype usedcrystal rectifiers. Such crystals are commonly composed of germanium, silicon, galena or similar substance.
  • FIG. 1 is a diagrammatic view showing a frequency-modulation system in accordance with our invention
  • Fig. 2 is a view in section showing a crystal assembly used in the preferred practice of our invention
  • Fig. 3 is a diagrammatic view showing a modification of our invention
  • Fig. 4 is a diagrammatic view showing a further modification of our invention.
  • Fig. 5 is a diagrammatic view showing still another modification of our invention.
  • Fig. 6 is a diagrammatic view showing a still further modification of our invention.
  • the apparatus shown in Fig. 1 comprises a generator of electrical oscillations 5 including an electric discharge device 1 which has an anode 9, a cathode II and a grid l3.
  • Anode potential is supplied to the discharge device from a source (not shown) through a resonant network
  • the grid I3 is biased negative with respect to the cathode II by operation of a'biasing network including a resistor shunted by a capacitor I9.
  • the biasing network is connected between the grid I3 and a frequency-determining network 2
  • the latter comprises an inductor 23 and a variable capacitor 25, and is connected to ground at the terminal remote from the biasing network.
  • the cathode I is connected to the inductor 23 at a point intermediate its terminals. The portion of the inductor between the cathode II and ground introduces a regenerative potential, causing the circuit including the discharge device I to oscillate.
  • a modulation network including a coupling capacitor 21 and a crystal assembly 29 is connected.
  • the crystal assembly 29 is preferably a 1N34 germanium detector such as is shown in Fig. 2 It comprises a cylindrical ceramic tube 30 closed at the ends by caps 32. From the center of one cap, a small metallic projection 34 extends. A particle 35 of crystalline germanium or other suitable material is secured to the projection. From the other cap 32, a fine wire 38 extends. The tip of the wire engages the germanium particle.
  • the assembly is approximately 4" in diameter and long and its distributed capacity is small. The essential element of the assembly is the crystal 35. The other components are provided for effecting connection with the crystal.
  • the crystal assembly is supplied with current from a modulating source, suchas a microphone circuit 3
  • the microphone circuit includes an output transformer 33, the secondary 35 of which is connected across the modulation network 2
  • This rectiher (31) may also be a 1N34 crystal assembly.
  • a condenser 39 is connected Across the secondary 35 of the transformer. This condenser and the rectifier 31 in series with the secondary operate to suppress the fiow of the oscillations produced in the generator through the microphone circuit 3
  • Signals impressed in the microphone circuit work.
  • the currents vary the resistance of the crystal, thus varying the net reactive component of the frequency-determining network 2
  • , the mean crystal resistance and capacity 21, are so set that the net resistive component of the frequency determining network is not varied. Accordingly, frequency modulations, but not amplitude modulations, are produced in the output of the oscillator.
  • the resonant network IS in the output circuit of the discharge device I is tuned to a multiple of the unmodulated frequency of the oscillator.
  • This network (I5) is inductively coupled to another resonant network 4
  • the latter resonant network (4 is tuned to the same frequency as the network I5 in the plate circuit of the first electric discharge device I.
  • the circuit including the discharge device 43 thus operates as a frequency multiplier.
  • additional frequency multipliers and amplifiers 45 may be interposed between the multiplier (l5, 4
  • the signals radiated by the antenna are free of alternating-current hum because the crystal 29 at the sensitive point in the transmitter circuit does not require filament current. Distortions and amplitude modulations are suppressed because the interelectrode capacity of the crystal 23 and its capacity to ground is small. The crystal is small and its electrodes have no tendency to be set into vibration by transmitter station sounds, and, therefore, the output signal is free of microphonic noises.
  • the rectifier 31 in series with the secondary 35 of the microphone transformer is replaced by a reactor 49.
  • This reactor and the capacitor 39 perform the function of suppressing oscilla tions from the generator 5.
  • our il'iVBl'1-' tion in its broadest aspects, comprehends within its scope a frequency-modulation system incliirl ihg the reactor, the system including the rectifier 31 in the secondary circuit in lieu of the reactor 49 is superior and is to be preferred.
  • the reactor has a tendency to introduce nonlinearity in the response of a modulation circuit.
  • is connected in parallel with the crystal 29. This capacitor cooperates with the coupling capacitor to properly divide the voltageacross the inductor 23 in the frequencydetermining network 2
  • Fig. 5 shows a circuit designed for high r.-f. current. In this a plurality of crystals are connected in parallel.
  • Fig. 6 shows a circuit in accordance with our invention designed for situations where the amplitude of the radio frequency oscillations exceeds thera ting-of single crystals;
  • a pair- (ora plurality) or crystals 53, 55-, 5,1 and 519 in series' may be: used.
  • the capacitor 21 may be replaced by a reactor of any other type such as an inductor.
  • Other reactances may be correspondingly varied.
  • the tube I may be, of: the gas filled type; for very high frequencies, it may be of the klystron type. In; the latter case, the networkv 21- is a resonator.
  • the crystal assembly 29 may in specific embodiments of my invention be of a difierent structure than the one disclosed. Where our invention is applied to relativelylow frequency systems, crystal assemblyhaving larger distributed capacity and capable of conductingcurrent or larger magnitudemay be used. Qur'invention, therefore, is, not toberestricted except insofar as is necessitated by the prior art and by thespiri t the appended claims. 7
  • a generator of electrical os cillations a frequency-determiningnetwork for said generator, a network shunting said frequency-determining network including a crystal. the resistance of which varies with the current flowing therethrough, means. for varying the currentfiow through said crystal, and meansinterposed between said shunting network and said varying means. for suppressing, the flow of, oscillations from: said generator through said vary-v ing means, said suppressing meansincluding a crystal and condenser in series.
  • a generator of electrical oscillations a frequency-determining network for said generator, a network shunting said frequency-determining network including a crystal, the resistance of which varies with the current flowing therethrough, means for varying the current fiow through said crystal, and means interposed between said shunting network and said varying means for suppressing the fiow of oscillations from said generator through said varying means, said suppressing means including a crystal rectifier.
  • a generator of electrical oscillations a frequency-determining network for said generator, a network shunting said frequency-determining network including a crystal, the resistance of which varies with the current flowing therethrough, means for varying the current flow through said crystal, and means interposed between said shunting network and said varying means for suppressing the flow of oscillations from said generator through said varying means, said suppressing means including a crystal.
  • a source of frequency-modulated oscillations comprising a generator of oscillations including a frequency-determining network, a network shunting said frequency-determining network including a crystal rectifier, means for varying the current flow through said rectifier, and another crystal rectifier interposed between said varying means and said shunting network.
  • a generator of electrical oscillations a frequency-determining network for said generator, a network shunting said frequency-determining network including a crystal, the resistance of which varies with the current flowing therethrough, and means for varying the current flow through said crystal, the magnitudes or the; components or said; networks: being.- so
  • a generator. of electrical oscillations a frequency-determining network for said generator, a. network shunting said .fretruancy-determining network including a crystal. the resistance of which varies with the current therethrough, and connections for varying the current through said crystal in accordance with a given signal to frequency modulate said generatori-n accordance with said-signal.
  • a generator of electrical oscillations a. frequenoys-dete'rmining network for said generator, a network shunting said free quency-determi ning' network including a crystal of' the: type that is electro-mechani'cally independent of said generator and the resistance of which varies with the current flowing therethrough, and connections for varying the current flow through said crystal.
  • a generator of electrical oscillations including a frequency-determining network, a network shunting said frequency-dctermining network including an electromechani- 3 cally inert crystal, the resistance of which varies with the current flow therethrough, and connections for varying the current flow through said crystal.
  • a modulation circuit the combination of a generator of electrical oscillations, a frequency determining network for said generator, a modulation network including a crystal shunting said frequency determining network, a source of modu lating signals, a modulation transformer connected to said source of modulating signals and having a secondary connected to said modulation network, and a suppressing circuit connected across said secondary.
  • a modulation circuit the combination of a generator of electrical oscillations, a frequency determining network for said generator, a modulation network including a crystal shunting said frequency determining network, a source of modulating signals, a modulation transformer connected to said source of modulating signals and having a secondary connected to said modulation network, and a suppressing circuit connected across said secondary including a crystal and a reactance in series.
  • a modulating network including a crystal element connected to said modulating source and shunting said resonant network, the resistance of said crystal element varying with the current flowing from the modulating source through the element, and a reactance connected between said resonant network and said modulating network.
  • said modulating network including a crystal element having a resistance which varies with the current through the element, and a capacitor having a relatively low impedance to said high frequency oscillations and shunting said crystal element.

Landscapes

  • Crystals, And After-Treatments Of Crystals (AREA)
US718498A 1946-12-26 1946-12-26 Frequency modulator Expired - Lifetime US2583138A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
BE478223D BE478223A (en, 2012) 1946-12-26
US718498A US2583138A (en) 1946-12-26 1946-12-26 Frequency modulator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US718498A US2583138A (en) 1946-12-26 1946-12-26 Frequency modulator

Publications (1)

Publication Number Publication Date
US2583138A true US2583138A (en) 1952-01-22

Family

ID=24886293

Family Applications (1)

Application Number Title Priority Date Filing Date
US718498A Expired - Lifetime US2583138A (en) 1946-12-26 1946-12-26 Frequency modulator

Country Status (2)

Country Link
US (1) US2583138A (en, 2012)
BE (1) BE478223A (en, 2012)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2853680A (en) * 1955-05-06 1958-09-23 Nuut August Phase modulator
US2980864A (en) * 1959-08-14 1961-04-18 Savage Ind Inc Voltage controlled oscillator
US3008095A (en) * 1958-08-25 1961-11-07 Arf Products Frequency-modulated oscillator
US3010016A (en) * 1958-01-20 1961-11-21 Motorola Inc Remote tuning radio receiver
US3061802A (en) * 1954-05-14 1962-10-30 Electro Mechanical Res Inc Frequency modulated crystal oscillator
US3127577A (en) * 1960-06-30 1964-03-31 Raytheon Co Frequency controlled oscillator

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1447793A (en) * 1921-08-19 1923-03-06 Latour Marius Radio receiving system
US1471418A (en) * 1923-05-26 1923-10-23 Charles Hanselmann Tuning transformer
USRE17356E (en) * 1929-07-02 Piezo-electric resonator
US1998119A (en) * 1932-08-19 1935-04-16 Bell Telephone Labor Inc Frequency changer and circuits therefor
US2033231A (en) * 1931-09-19 1936-03-10 Rca Corp Modulation system
GB491103A (en) * 1937-04-12 1938-08-26 Gen Electric Co Ltd Improvements in or relating to electrical frequency changing apparatus
US2182377A (en) * 1937-05-01 1939-12-05 Radio Patents Corp Method and means for tuning electric oscillatory circuits
US2222048A (en) * 1938-11-23 1940-11-19 Union Switch & Signal Co Apparatus for the production of electric oscillations
US2298437A (en) * 1940-06-05 1942-10-13 Rca Corp Frequency modulation
US2306555A (en) * 1940-05-23 1942-12-29 Research Corp Method for frequency control
US2424246A (en) * 1943-09-16 1947-07-22 Bell Telephone Labor Inc Frequency-modulated crystal oscillator
US2461307A (en) * 1944-11-13 1949-02-08 Rauland Corp Modulating system
US2473556A (en) * 1943-03-15 1949-06-21 Carl A Wiley Device for controlling oscillating circuits

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE17356E (en) * 1929-07-02 Piezo-electric resonator
US1447793A (en) * 1921-08-19 1923-03-06 Latour Marius Radio receiving system
US1471418A (en) * 1923-05-26 1923-10-23 Charles Hanselmann Tuning transformer
US2033231A (en) * 1931-09-19 1936-03-10 Rca Corp Modulation system
US1998119A (en) * 1932-08-19 1935-04-16 Bell Telephone Labor Inc Frequency changer and circuits therefor
GB491103A (en) * 1937-04-12 1938-08-26 Gen Electric Co Ltd Improvements in or relating to electrical frequency changing apparatus
US2182377A (en) * 1937-05-01 1939-12-05 Radio Patents Corp Method and means for tuning electric oscillatory circuits
US2222048A (en) * 1938-11-23 1940-11-19 Union Switch & Signal Co Apparatus for the production of electric oscillations
US2306555A (en) * 1940-05-23 1942-12-29 Research Corp Method for frequency control
US2298437A (en) * 1940-06-05 1942-10-13 Rca Corp Frequency modulation
US2473556A (en) * 1943-03-15 1949-06-21 Carl A Wiley Device for controlling oscillating circuits
US2424246A (en) * 1943-09-16 1947-07-22 Bell Telephone Labor Inc Frequency-modulated crystal oscillator
US2461307A (en) * 1944-11-13 1949-02-08 Rauland Corp Modulating system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3061802A (en) * 1954-05-14 1962-10-30 Electro Mechanical Res Inc Frequency modulated crystal oscillator
US2853680A (en) * 1955-05-06 1958-09-23 Nuut August Phase modulator
US3010016A (en) * 1958-01-20 1961-11-21 Motorola Inc Remote tuning radio receiver
US3008095A (en) * 1958-08-25 1961-11-07 Arf Products Frequency-modulated oscillator
US2980864A (en) * 1959-08-14 1961-04-18 Savage Ind Inc Voltage controlled oscillator
US3127577A (en) * 1960-06-30 1964-03-31 Raytheon Co Frequency controlled oscillator

Also Published As

Publication number Publication date
BE478223A (en, 2012)

Similar Documents

Publication Publication Date Title
US2091546A (en) Short wave converter
US2583138A (en) Frequency modulator
US2855568A (en) Semi-conductor oscillation generators
US2426295A (en) Frequency modulation system with crystal oscillator
US2925563A (en) Frequency modulation system
US2394427A (en) Wave length modulation
US2233778A (en) Automatic frequency control circuit
US2459557A (en) Wave length modulation
US2426193A (en) Radio transmitter automatic volume control
US1898181A (en) Oscillation generation
US2469289A (en) Frequency modulation
US2171148A (en) Superregenerative receiver
US2445618A (en) Modulation system
US2668232A (en) Frequency controlling system
US2378245A (en) Variable frequency oscillator
US2313071A (en) Oscillation generator and modulator
US1996830A (en) Amplifier
US2587718A (en) Modulation system and method
US2141292A (en) Radio receiver
US2119357A (en) Oscillation generator
US2282861A (en) Oscillator
US2463275A (en) Modulation
US2218526A (en) Transmission of frequencymodulated waves
US2407424A (en) Electron capacity and electron capacity modulator
US2510026A (en) Frequency modulation system for microwave generators