US2440264A - Modulator system - Google Patents

Modulator system Download PDF

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Publication number
US2440264A
US2440264A US506412A US50641243A US2440264A US 2440264 A US2440264 A US 2440264A US 506412 A US506412 A US 506412A US 50641243 A US50641243 A US 50641243A US 2440264 A US2440264 A US 2440264A
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US
United States
Prior art keywords
tube
bias
pulses
grid
carrier
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
US506412A
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English (en)
Inventor
Donald D Grieg
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 BE474951D priority Critical patent/BE474951A/xx
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to US506412A priority patent/US2440264A/en
Priority to GB19853/44A priority patent/GB600253A/en
Priority to ES0181843A priority patent/ES181843A1/es
Application granted granted Critical
Publication of US2440264A publication Critical patent/US2440264A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K7/00—Modulating pulses with a continuously-variable modulating signal
    • H03K7/08—Duration or width modulation ; Duty cycle modulation

Definitions

  • This invention relates to carrier communication systems and more particularly to systems for pulse modulation of carrier waves wherein the pulses vary in time and/or width according to a signal wave.
  • Such telegraph keying circuits generally include a keying amplifier tube whereby the keying is performed either by controlling the grid bias or the plate bias thereof. Keying of the amplifier at a rapid rate and at variations either in pulse amplitude, width or timing, produce variations in the output of the tube from signal to signal and this results in carrier pulses or envelopes which vary both in the steepness of the slopes of the leading and trailing edges and in amplitude.
  • Another object of the invention is to provide a carrier wave modulating system wherein the leading and trailing edges of the carrier envelopes produced are substantially vertical and consistently formed; also wherein the average peak voltage of the envelopes is the same as the peak voltage of the umnodulated carrier wave.
  • Another object of the invention is to provide a system for pulse modulation of a carrier wave in which the peak voltage of the output carrier is selectively adjusted.
  • Fig. 1 is a schematic wiring diagram of a carrier modulating system according to my invention.
  • Fig. 2 is a graphical illustrationused for explaining the operation of Fig. 1.
  • a modulating system whereby a carrier wave is produced and pulse modulated by voice signals although signal sources other than voice may, of course, beused.
  • Any form of .pulse generator wherein the pulses are adapted to be displaced or varied in width or time displacement in accordance with the modulating signals may be provided.
  • a known form of cusper modulator I0 is shown to which a source l2 of sinusoidal voltage is applied.
  • the cusper modulator may be of the symmetrical pulse generating type or it may be of the biased type such as disclosed in the copending application of E. Labin and D. D. Grieg, Serial No. 455,897, filed August 24, 1942 since issued as Patent No. 2,416,329.
  • FIG. 1 One manner of operation of this type of modulator is illustrated by curves 15 of Fig. 1 wherein 12a represents the sinusoidal Wave of the oscillator l2.
  • the modulator Ill is of the push-pull rectifier type wherein the wave l a is fully rectified.
  • the modulator In is preferably biased to an offset condition'as indicated by the axis Illa.
  • the full-wave rectification of wave 12a produces cusps 16, ll, l8, l9, etc., which when clipped and shaped by a shaper circuit 20 produces a series of pulses 25, 21, 28, 29, etc., which may be of either negative or positive polarity whichever is desired.
  • the oscillator includes a vacuum tube 33 to which an LC circuit is connected in the grid-to-cathode circuit thereof.
  • the plate 33 is supplied with a positive potential at 31 through load resistor 38.
  • the oscillator 32 is adapted to produce a carrier wave '44), such as shown at curve a, of the desired frequency.
  • I connect a, three-electrode vacuum tube 42 with the plate 43 and the cathode 44 connected across the terminals of the circuit.
  • I couple the output'connection 22 of the shaper 20.
  • the grid 45 is provided with a grid leak 41 which may be-connected by contacts 48, '49 to the cathode '44 for zero' bias or by contacts '48, '5il'to a negative source of potential.
  • the signal pulses normally ranging in duration from about one-third to three or four microseconds, more or. less. microsecond, for example, would include about 30 ormore cycles of oscillation dependent, of course, on the carrier wave frequency. It will be understood, however, that when the tube 42 is biased to cut-off, the oscillations of the circuit 32 will immediately build-up as indicated at 56 to the full amplitude of oscillation and that when the cut-off bias is removed, regardless of the instant'voltage of an oscillatory swing, the oscillationsare terminated withinone-half of a cycle.
  • the trailing edge, like the leading edge, of each carrier pulse envelope is consistently-defined as substantially vertical. The leading edge of the carrier pulse envelope corresponds accurately in time to the leading edge of the corresponding signal pulse while the trailing edge is accurate within the timing of one-half cycle of the carrier wave.
  • the carrier wave modulator of my invention may even produce more truly rectangular pulse envelopes than that of the modulating pulses. This is so because the modulating tube 42 either permits the initiation of a positive undulation or absorbs substantially completely the energy attempting to form same, as the case may be.
  • the frequency of pulse modulation by my system is only limited by the capacity of the plateto-cathode electrodes of the tube 42. If this capacity is high, the tube will not cut-off at a high pulsing rate. this regard to select a tribe of low capacity.
  • the load resistor or attenuator 3B is calibrated, preferably in mi-crovolts, and bridged by a voltmeter Bil
  • a given R. F. carrier voltage across attenuator 38 may be obtained for calibration of the attenuator 38 by observing the meter 60.
  • a carrier wave of any desired peak voltage may be obtained and read directly from the attenuator 38.
  • the carrier pulses 26a, 21a, etc. are of the same amplitude as the unmodulated carrier wave 40, independent of the modulating pulse width, amplitude, frequency, etc., a measurement of the carrier wave 4!] by closing contacts 48, 50, determines the peak amplitude of the carrier pulse envelopes.
  • This accurate measurement of the carrier wave is very useful for testing receivers, not only for different peak voltages for input signals, but also for different carrier frequencies since the peak voltage of the carrier is not changed by change in frequency.
  • a modulating system comprising an oscillator having an oscillatory tank circuit for producing an oscillatory wave, a vacuum tube having plate, cathode and grid electrodes, means connecting said plate and cathode electrodes across a part of said oscillator tank circuit, means for connecting the grid electrode to a source of pulses of negative polarity, .a grid leak, and means ccnnecting said grid leak to the cathode electrode to normally give the grid electrode zero bias, such zero bias condition functioning to permit said tube to conduct upon occurrence of positive halves of oscillations thereby preventing occurrence of oscillations during such zero bias con-'- dition, and said pulses of negative'polarity opcrating to bias the tubeto'cut-ofi-thereby render.
  • said oscillator includes a load resistor calibrated according to a desired graduated output for different points along said resistor, and output means selectively connectable to said resistor at said points, whereby the peak power of the output oscillations is determinable.
  • said oscillator includes a load resistor calibrated according to a desired graduated output for difierent points along said resistor and output means selectively connectable to said resistor at said points, and wherein the grid electrode of said tube is provided with means for biasing the tube to cut-ofi thereby enabling the oscillator to operate continuously so that the average voltage drop across said resistor corresponding to the peak voltage output thereof is obtainable by measuring said voltage drop.
  • means to control the oscillating operation of said circuit including a vacuum tube having its plate and cathode electrodes connected across said oscillatory circuit and its grid electrode arranged for connection with a source of potential, said output circuit being provided with a calibrated load resistor and a voltmeter connected across said resistor, means to apply a given potential to said grid electrode to render said tube non-conductive to oscillations in said oscillatory circuit thereby enabling said voltmeter to indicate a steady voltage drop across said resistor, whereby the calibrations of said resistor may be valuated, and output means connectable at selectable points along the length of said resistor, whereby oscillations of a desired peak power are obtainable.
  • a modulating system comprising an oscillator having an oscillatory tank circuit for producing an oscillatory wave, a vacuum tube having plate, cathode and grid electrodes, means connecting said plate and cathode electrodes across a part of said oscillator tank circuit, means for connecting the grid electrode to a source of pulses of a given polarity, grid bias means, and means connecting said grid bias means to normally give the grid electrode a given bias, such bias condition functioning to permit said tube to conduct upon occurrence of given halves of oscillations thereby preventing occurrence of oscillations during such bias condition, and said pulses of given polarity operating to bias the tube to cut-of! thereby rendering said tube non-conductive so as to permit said oscillator to produce oscillations during the occurrence of said pulses.
  • a modulating system comprising an oscillator having an oscillatory tank circuit for producing an oscillatory wave, a vacuum tube having plate, cathode and grid electrodes, means connecting said plate and cathode electrodes across a part of said oscillator tank circuit, means for connecting the grid electrode to a source of pulses of negative polarity.

Landscapes

  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Particle Accelerators (AREA)
US506412A 1943-10-15 1943-10-15 Modulator system Expired - Lifetime US2440264A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE474951D BE474951A (ru) 1943-10-15
US506412A US2440264A (en) 1943-10-15 1943-10-15 Modulator system
GB19853/44A GB600253A (en) 1943-10-15 1944-10-13 Electric pulse modulation systems
ES0181843A ES181843A1 (es) 1943-10-15 1948-01-24 MEJORAS EN SISTEMAS DE ONDULACIoN

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US506412A US2440264A (en) 1943-10-15 1943-10-15 Modulator system

Publications (1)

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US2440264A true US2440264A (en) 1948-04-27

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Application Number Title Priority Date Filing Date
US506412A Expired - Lifetime US2440264A (en) 1943-10-15 1943-10-15 Modulator system

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US (1) US2440264A (ru)
BE (1) BE474951A (ru)
ES (1) ES181843A1 (ru)
GB (1) GB600253A (ru)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2613347A (en) * 1945-09-12 1952-10-07 Todd William Modulator, for radiosonde apparatus
US2633494A (en) * 1946-03-23 1953-03-31 Maynard D Mcfarlane Facsimile transmitting system
US2689344A (en) * 1951-05-15 1954-09-14 Stanley R Rich Pulse modulated speech transmission system
US2765211A (en) * 1953-12-09 1956-10-02 Applied Science Corp Of Prince Grid printer
US2807781A (en) * 1953-01-08 1957-09-24 Servo Corp Of America Direct-reading frequency meter
US2964240A (en) * 1953-08-28 1960-12-13 Electro Mechanical Res Inc Plotter
US2985845A (en) * 1957-04-05 1961-05-23 Westinghouse Canada Ltd Crystal oscillator keying circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4597068A (en) * 1983-04-21 1986-06-24 At&T Bell Laboratories Acoustic ranging system

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB187457A (en) * 1921-10-28 1922-10-26 Benjamin Henry Noel Hans Hamil Improvements in or relating to thermionic valve transmitters for wireless signalling
US1566245A (en) * 1921-09-02 1925-12-15 Westinghouse Electric & Mfg Co Radiotelephone system
DE462849C (de) * 1925-12-14 1928-07-18 Lorenz Akt Ges C Einrichtung zur Steuerung von fremderregten Roehrensendern
US1695042A (en) * 1923-08-15 1928-12-11 Western Electric Co High-efficiency discharge-device system
US2161087A (en) * 1934-12-17 1939-06-06 Philips Nv Oscillator of the magnetron type
US2255727A (en) * 1939-02-23 1941-09-09 W E Lehnert Signal generator output equalizer

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1566245A (en) * 1921-09-02 1925-12-15 Westinghouse Electric & Mfg Co Radiotelephone system
GB187457A (en) * 1921-10-28 1922-10-26 Benjamin Henry Noel Hans Hamil Improvements in or relating to thermionic valve transmitters for wireless signalling
US1695042A (en) * 1923-08-15 1928-12-11 Western Electric Co High-efficiency discharge-device system
DE462849C (de) * 1925-12-14 1928-07-18 Lorenz Akt Ges C Einrichtung zur Steuerung von fremderregten Roehrensendern
US2161087A (en) * 1934-12-17 1939-06-06 Philips Nv Oscillator of the magnetron type
US2255727A (en) * 1939-02-23 1941-09-09 W E Lehnert Signal generator output equalizer

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2613347A (en) * 1945-09-12 1952-10-07 Todd William Modulator, for radiosonde apparatus
US2633494A (en) * 1946-03-23 1953-03-31 Maynard D Mcfarlane Facsimile transmitting system
US2689344A (en) * 1951-05-15 1954-09-14 Stanley R Rich Pulse modulated speech transmission system
US2807781A (en) * 1953-01-08 1957-09-24 Servo Corp Of America Direct-reading frequency meter
US2964240A (en) * 1953-08-28 1960-12-13 Electro Mechanical Res Inc Plotter
US2765211A (en) * 1953-12-09 1956-10-02 Applied Science Corp Of Prince Grid printer
US2985845A (en) * 1957-04-05 1961-05-23 Westinghouse Canada Ltd Crystal oscillator keying circuit

Also Published As

Publication number Publication date
ES181843A1 (es) 1948-03-01
GB600253A (en) 1948-04-05
BE474951A (ru)

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