US2495768A - Electric pulse modulator - Google Patents

Electric pulse modulator Download PDF

Info

Publication number
US2495768A
US2495768A US19088A US1908848A US2495768A US 2495768 A US2495768 A US 2495768A US 19088 A US19088 A US 19088A US 1908848 A US1908848 A US 1908848A US 2495768 A US2495768 A US 2495768A
Authority
US
United States
Prior art keywords
anode
gap
signal
discharge
voltage
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
US19088A
Other languages
English (en)
Inventor
Reeves Alec Harley
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.)
International Standard Electric Corp
Original Assignee
International Standard 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
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US2495768A publication Critical patent/US2495768A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/43—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of beam deflection tubes
    • 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

  • the present invention relates to electric pulse modulating circuits employing cold cathode gasfilled discharge tubes.
  • the principal object of the invention is to reduce the operating cost and increase the life of pulse modulating circuits, by employing cold cathode gas-filled tubes as modulators.
  • Such tubes require no heater supply, thereby avoiding a source of energy consumption, and n activated cathode surfaces which tend to lose their properties in time.
  • the absence of any heater supply also facilitates the automatic switching on of the circuit by a control signal, since the only source which has to be switched is the high tension source.
  • the invention provides an electric pulse time modulator comprising a cold cathode gas filled electric discharge tube having a principal discharge gap, means for applying to the gap a maintaining potential insumcient to initiate a discharge across the gap, means controlled by a modulating signal wave for periodically firing the gap at times depending on the instantaneous signal voltage, means for periodically extinguishing the discharge, and means for deriving time modulated pulses from the gap.
  • Figs. 1 and 3 show schematic circuit diagrams of two embodiments of the invention.
  • Figs. 2 and 4 show wave form diagrams emplayed in explaining the operation of Figs. 1 and 3, respectively.
  • Fig. 1 shows a cold cathode tube l, filled with a suitable gas, or mixture of gases, at a suitable pressure, having an anode 2 and a cathode 3, both of which electrodes may be of any convenient and electrically suitable shapes.
  • 4 is a second trigger anode preferably spaced at a smaller distance from cathode 3 than anode 2.
  • the anode 2 is connected through resistor 5 and one winding of signal-frequency transformer 5 to the positive terminal of battery 1, having its negative end grounded.
  • Cathode 3 is connected to ground through variable resistor 9, shunted by condenser it.
  • the trigger anode 4 is connected through resistor i i and one Winding of signal frequency transformer i2 to a tapping on battery 1.
  • Condenser l3 shunts the pulse frequency components but not the signal frequencies.
  • the recurrence frequency of the pulses of Fig. 2 (a) should be at least twice that of the highest modulating signal frequency component; for speech of commercial quality it should be at least 8 k. c., and preferably at least 10 k. c.
  • a repeated wave having the form shown in Fig. 2 (b) and the same recurrence frequency as the pulses, Fig. 2 (a) is applied to the anode 4 through resistor l6 and blocking condenser II.
  • the modulating signal voltage is applied at terminals 18 and to the primary winding of transformer I2, which should have a ratio suitable to match the impedance of the signal line to the impedance of the secondary winding circuit when anode 4' is not discharging.
  • the circuit of anode 4 may be adjusted either (a) so that once anode 4 is fired it continues discharging until the local wave of Fig. 2 (b) quenches it at times A, C, E etc., or alternatively (b) so that once fired, anode 4 immediately starts a squeg and quenches itself in the mannner explained in the specification of co-pending U. S. application Serial No.
  • Fig. 2 shows a typical portion of the modulating signal voltage after arrival at anode 4.
  • the sum of 2 (b) and 2 (c), as shown by curve 2 (d), will represent the total voltage applied to the anode 4 due to the signal and the local wave 2 (b).
  • the linearity of the modulation may be improved if necessary, at the expense of gain, by adding a given amount of negative feed-back.
  • This is achieved by resistor 9, shunted by condenser Ill.
  • the time constant of elements 9, I0 should be adjusted so that the pulse-frequency components are substantially shunted by [0, but not the signal frequencies. In this case, as the output rises, the signal-frequency voltage across ID will rise, which will tend to delay the firing of anode 4, and thus to reduce the output.
  • the action in reducing distortion components is exactly similar to that of the usual negative feed-back amplifier.
  • the negative feed-back obtained is proportional to the value of resistor 9. If full gain and no feed-back is required, resistor 9 is reduced to zero.
  • FIG. 3 A modification of the circuit of Fig. 1 which does not employ any locally generated waves is shown in Fig. 3. Many of the elements are the same as in Fig. l, and have been given the same designation numbers, and will not be again described. Elements M to IT have been omitted. A resistor 20, shunted by a condenser 2
  • the constants including the values of elements 20 and 2
  • should be very small (only a few micromicrofarads.) and the time constant of elements 20, 2
  • the actual moment at which anode 4 will be refired depends on the momentary value of the signal voltage.
  • the signal wave is that shown in Fig. 4 (a) anodes 4 and 2 will be refired progressively earlier after each squeg.
  • the resulting voltage across the condenser 2! is shown in Fig. 4 (b).
  • the result is a frequency modulation of the squeg by the signal, as shown.
  • each pulse will be substantially constant, but the time interval between successive pulses will be modulated in accordance with the applied signal voltage.
  • the frequency modulated pulses may be obtained as before from terminals [9.
  • the tube l of Figs. 1 and 3. preferably contains 92% neon, 1% argon and 7 hydrogen at a total pressure of mm./Hg.
  • the three electrodes are preferably pure nickel rods 5 mm. long and 1 mm. in diameter, rods 2 and 3 being arranged end to end in line with a 5 mm. gap between them, anode 4 also being parallel to 3, and spaced 5 mm. from 2.
  • the time interval A-B of Fig. 2 (a) may be reduced to about 5 microsecs., allowing for effective handling of signal frequencies up to about 50 k. c.
  • the circuit of Fig. 3 with the same tube gives a minimum squeg period of about 6 microsecs.
  • both circuits, Figs. 1 and 3 produce pulses which are'modulated in respect of a time characteristic.
  • the characteristic is the pulse duration, and in Fig. 3 it is the period between pulses.
  • An electric pulse time modulator comprising a cold cathode gas-filled electric discharge tube having a principal discharge gap, means for applying to the gap a maintaining potential insufiicient to initiate a discharge across the gap, means controlled by a modulating signal wave for periodically firing the gap at times depending on the instantaneous signal voltage, means for periodically extinguishing the discharge, and means for deriving time modulated pulses from the gap.
  • An electric pulse duration modulator comprising a cold cathode gas-filled electric discharge tube having a cathode; a principal anode, and a trigger anode forming a principal gap and a trigger gap, means for applying across the principal gap a maintaining potential insufficient to initiate a discharge thereacross, means for applying between the trigger anode and the cathode a train of regularly repeated voltage waves of saw-tooth form together with a modulating signal voltage wave in such manner as to fire the trigger gap at a.time during each period of the saw tooth waves depending on the signal voltage, means for periodically extinguishing the discharges across both gaps, and means for deriving duration modulated pulses from the principal anode.
  • An electric pulse frequency modulator comprising a cold cathode gas-filled electric discharge tube having a cathode, a principal anode, and a trigger anode forming a principal discharge gap and a trigger discharge gap, means for applying across the principal gap a maintaining potential insufficient to initiate a discharge thereacross, a
  • the arrangement being such that the combined voltage is sumcient to fire the trigger gap thereby causing the principal gap to fire and extinguish both discharges by squegging, in such manner that the charge acquired by the condenser prevents reflring of the trigger gap for a period determined by the time constant of the said resistance and condenser, and means for deriving frequency modulated pulses from the principal anode.
  • a modulator according to claim 2 comprising means for applying to the principal anode a train of negative pulses regularly repeated at the same frequency as the saw tooth waves for periodically extinguishing the discharge cross the principal gap.
  • each saw tooth wave is followed by a short nega- 20 Number amplitude to xtinguish the discharge across the trigger gap.

Landscapes

  • Lasers (AREA)
  • Generation Of Surge Voltage And Current (AREA)
  • Plasma Technology (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Emergency Protection Circuit Devices (AREA)
US19088A 1947-05-12 1948-04-05 Electric pulse modulator Expired - Lifetime US2495768A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB12769/47A GB659806A (en) 1947-05-12 1947-05-12 Improvements in or relating to electric pulse modulators

Publications (1)

Publication Number Publication Date
US2495768A true US2495768A (en) 1950-01-31

Family

ID=10010795

Family Applications (1)

Application Number Title Priority Date Filing Date
US19088A Expired - Lifetime US2495768A (en) 1947-05-12 1948-04-05 Electric pulse modulator

Country Status (4)

Country Link
US (1) US2495768A (en))
BE (1) BE482827A (en))
ES (1) ES183609A1 (en))
GB (1) GB659806A (en))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2791725A (en) * 1951-04-28 1957-05-07 Northrop Aircraft Inc Diode pulse amplifier

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1875151A (en) * 1928-02-07 1932-08-30 Westinghouse Lamp Co Glow relay tube
US1898486A (en) * 1931-11-02 1933-02-21 Wired Radio Inc Modulation system
US2441958A (en) * 1944-07-17 1948-05-25 Standard Telephones Cables Ltd Communication system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1875151A (en) * 1928-02-07 1932-08-30 Westinghouse Lamp Co Glow relay tube
US1898486A (en) * 1931-11-02 1933-02-21 Wired Radio Inc Modulation system
US2441958A (en) * 1944-07-17 1948-05-25 Standard Telephones Cables Ltd Communication system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2791725A (en) * 1951-04-28 1957-05-07 Northrop Aircraft Inc Diode pulse amplifier

Also Published As

Publication number Publication date
ES183609A1 (es) 1948-07-01
GB659806A (en) 1951-10-31
BE482827A (en))

Similar Documents

Publication Publication Date Title
US2428149A (en) Impulse generator
US2551101A (en) Electrical ignition system
US2553263A (en) Traveling wave vapor-electric current generator
US2235667A (en) Relaxation oscillator
US2495768A (en) Electric pulse modulator
US2511595A (en) High-frequency pulse generator
US2516915A (en) Gaseous discharge device
US2418375A (en) Production of delayed pulses
US2457125A (en) Circuit arrangement for producing electrical pulses
US2432180A (en) Radio pulse-echo system
US2534261A (en) Line pulse modulator
US2710351A (en) Pulse generator
US2665068A (en) Add-subtract binary counter circuit
US2549807A (en) Inverter tube protective device
US2593486A (en) Electric discharge tube
US2446838A (en) Pulse forming circuit
US2645742A (en) Electric discharge device
US2537383A (en) Device for extinguishing a discharge tube having a mercury cathode
US2496980A (en) Pulsed oscillator
US2621294A (en) Circuit for providing timed electrical impulses
US2190552A (en) Gas tube circuit
US3105169A (en) Pulse generator
US2304998A (en) Signal controlled keying circuit
US2793290A (en) Rectangular pulse generator
US2428616A (en) Electrical protective device