US2462885A - Pulsed oscillator - Google Patents

Description

March 1, 1949. J.- R. M ORE 2,462,885

} PULSED OSCILLATOR Filed NOV. 28, 1942 KEYING 2 PULSE 3 RF OSCILLATOR GENERATOR OSCILLATOR FIG I INVENTOR JAMES R. MOORE A TTORNE Y especially'such as areused in pulse-echo systems and the other end-.of th'EhCOilw is connectedr to short distance away. Sharp pulses also permit Coils 3! anda34, togethenwithrth di t ibut d cuits in greater detail. The output of oscillator a. very rapid surgefofpotential across resistorrzd grid and cathode of a gas tube 23. This tube ing is oscillations beinggenerated for theduram fiatenteci Mar. 1 il94 I UNITED p STATES J OEFIEZEijL a 7 2,462,885 a Q 3 PULSED OSCILLATFOE- James R4 Moore, RumsonyN-i J., assigiiorto tl iel United States of America as represented by the Secretary of War Application November 28, 1942, Serial N'.'467,269 14 Claims. (01. 250 -36) 7 (Granted under theact oflMarchB, 1883, as.

amended April 30, 1928; 3700; G. 757).

The invention described herein maybe manuacondenser 25. and resistor-26,:which may beylfon factured and usedby orfor the Government. for example, of the order of L,0.00:ohms-.. governmental purposes, without the payment to The-high potential side of resistor-26 isconme of any royalty thereon. nected tothecenter-tap .of-acoil-3Lw One-end Thistinvention relates to radio transmitters, 5 of. this coil ishconnected to the plate oftube -iz of object detection. the plate of tube 33. The cathodes ofxbothtubes It is frequently necessary in such systems .to are grounded; The-grids oflsaid tubes-are cone make the pulses as sharpas possible inorderto nected to=opposite ends .of-a coil 34; thelcenter avoid confusion between the transmitted pulses 10 tap of which is connected to -ground througlr a and the pulses reflected from objects a relatively high resistance 35, of the order of 20,0;00 ohrns.

use of large peakpowers and at the same time capacity and interelectrode. capacities. therekeep the average power at a relatively low level. acrossyform thet resonatingztank cincuitsvforthe It is therefore an object of this invention to plates andrgrids, respective1y-,-of.radio frequency devise a radio frequency transmitting system oscillatingmubes lz and 33 .connectedi for: pushwhich can be used for emitting very sharp pulses pull operation. Feedbackibetweenthe-plateiand of radio frequency energy. grid circuits to maintain: oscillation: is. produced It is a. further object of this invention to deby, electromagnetic coupling between plate and vise an improved method of pulse modulating a grid coils 3i and or by means-of the intertransmitter of radio frequency waves. electrodecapacitances, or by;-bothmexpedients. Further objects will be apparent from the fol- The radio frequency outputof the oscillatorwis lowingspecification and drawings, wherein like fedto an antenna, either directly or through a reference numerals indicate like parts and series; ofpowenamplifiers;-by-meansvofia coili36 wherein: coupled to thecoilSl. V Figure 1 is a blockdiagram of a pulse trans- The above'described-system operates asfollows: mitter system; Whenthe-voltageapplied'through transformer,

Figure 2 is a schematic diagram of the circuits [2, from? the keyingvoscillator I to the grid of used in Fig. 1; and tube=23; is negative,-the other circHitLparameters Figure 3 is a schematicdiagram of a modifica- Q are such that the gas tube is non-conducting: tion of the invention. Under such conditions, the condenser 25.;(Wi11 b6 Referringto Fig. 1, a keying oscillator I, of charged to. substantially the full voltage ofplate relatively low frequency, is connected to a pulse source 2'! throughresistors 24 and- 26;- When generator of such construction that it generates the condenser becomescharged, the; current a sharp pulse of potential at every cycle of current through resistor 26 drops to zero andttherefore from the keying'oscillator. The sharp pulse of the voltage applied to anodes,cr me-oscillator potential is used toenergize the tubes of a radio 1111088632 and 33" is zero. W frequency oscillator 3, Which in turn generates When the grid 'ofgas tube23 becomes suflicienti radio frequency power for the duration of said ly positive, the'tube dischargeslandrin turnJzdue pulse. The output of the oscillator is radiated 40 tothe low resistance .of the anode-cathodetpath from, aldirectional antenna 4 connected thereto. of c said tube, condenser 25.:dischargesnsuddenl5t Figure 2 illustrates the abovementioned cirthrough:.said tub.e andwresistor 2-6;.resulting1in I is connected to the primary of a transformer said-surge isapplied: to the anodesvofntubesyw [2, the secondary of which is connected to the and 33 of the radio frequencycoscillator .results.

isof the grid controlled arc-discharge type, one tionrof=thepulse; brand of which is generally known by the trade The durationofthe pulse:is determined bycthe. mark.Thyratron. The plate of tube 23 is contime constant of the--Ro 0; network constituted, nected to the grounded positive pole of the plate 5 by resistor 26 and condenser. 25, the, anodes potential source 21. The cathode of said tube cathode resistance of tube 23-beingnegligible is connected to the negative pole of source 2'! When condenser 25 is. completely dis har ed, the through a high resistance 24. which for example, anode-cathode path of tube23 becomes deionized; y be of the Order Of 100,000 s. e becauseresistor it'depresses: the plate.potentiah cathode isalso connected to the ground through below the operating" level-, andl the grid again,

" oscillator frequency.

of a transformer 28, the j whichis applied to the anodes of oscillator tubes! I 32 and 33. The transformer sharpens the pulse Other elements ,other pole of regains control until the next positive alterna tion-from the'keying oscillator l; Thus a sharp pulse is generated at eachcycle of the keying Figurel3 is. similar to Fig. 2 withlthe exception that condense? 25 discharges through the primary secondary output of and permits more effective isolation of the'pulse generating oscillator and. the radio frequency oscillator.

The above described circuits have several features which permit safety and economy of. ,operation. Only one high voltage lead isnecesconnected to one pole of a source of plate potential and to ground, said cathode being conneeted to one end of a resistor the other end of which is connected to .the other pole of said source, a condenser connected directly to said cathode, the'other side .of'said condenser being connected to one end of a second resistor the sary'to couple the keying circuit'to the oscillaton,

There is nohigh voltage on the transmitter during intervals between pulses permitting "less severe insulation requirements. A particular feature is the absence of'direct current potentials in the oscillator circuitsythus reducing hazard to I personnel during -tune-up periods. Only those elements It isto be understood that many variations are "possible which will readily suggest themselves to one skilled in the art. Iclaimr; 1. A pulse generator comprising a tube having a a cathode, an anode, and a grid, said gridbeing .jconneiited to a source of control potential, said anode being of plate potential and to ground, said cathode being connected to one endof a resistor the connected to a one pole of a source other end of which is connected to the other pole of said source, a condenser connected di-.

a cathode, an anode, and a grid, said grid being connected to asource of controlpotential, said anode being'connected to one pole of va source of 1 plate potential potential and to ground, said cathode being gconnected to one end of a resistor theother end of which is connectedto the said source, a condenser connected directly to said cathode, the other'side of said .condenser being connected to: one: end of asec-' o'nd resistor the other side of which is connect- ,edjto groundgand an' output circuitcou-pled to one of said'resistors.

3., A pulse generatorcomprising agas' tube of thearc dischargetype having a cathode, an anode,"and a grid, said grid beingconnected to a source of control potential, said anode being I connected to one pole of a sourceof plate poten tial and to ground, said cathode'being connected "to' one end of ,a resistor the other end of. which is oonnectedto the other pole of said source, a condenser connected directly to said cathode, the

" other side offsaid condenser being connected to one end of a second .resistorthekother sideof which is; connected to ground, 'said'second resistor being a' small fraction of the'value of said first mentioned resistor, and an output circuit coupled to said-second resiston r H v 4. A pulsegenerator comprismg'a gastube of I the arc discharge type having a'lcathode, an

jator. '5'. A

other side of which is connected to ground, one ofv said resistors being a small fraction of the value of the other, and a'transformer, the primary of which is .connected across said second mentioned resistor and the secondary of which constitutesthe output circuit of .the pulse generpulse generator comprising a tube having a cathode, an anode, and a grid said grid being connected to a source of control potential, said anode being connected to onepole of a source of plate potential and to ground, said cathode being connected to one endof a resistor the other end of which is connected to the other. pole of said source, a condenser connected directly to of a complete transmitting system have been shown which are neces- 'sary''to explain the operation) of the a system.- I of" such a system have not been shown 'or described, since they areconventional.

said. cathode, the other side of saidcondenser beingconnected to one end'of a. second resistor the other side of which is connected. to ground, and a transformer, theprimary of which is connected across said second mentioned resistor and the secondary of whichconstitutesthe output circuit of the pulse generator, v 6.-A pulse generator comprisinga gas tube of the arc discharge type having a cathode, an

anode, and agrid said grid being connected to a source of control potential, said anode being connected to one pole of asource of plate potential and to ground, said cathode being'connected to one end of a resistor the other end of which is connected to the other pole of said source, a condenser connected directly .to said cathode, the

: other side of said condenser beingconnected to one 'end of a second. resistor, the other end of which is connectedto ground,and a transformer,

" the primary" of which is connected across said second mentioned resistor and'the secondary of which co'nstitutesthe output circuit of the pulse generator.

'1. A radiopulse'transmitter including at least a pair of electron tubes,one tube having its anode grounded, the other tube having its cathode grounded, a pulse transformer, a circuit including one of said tubes and the primary of said transformer to charge and discharge said condenser at spaced intervals, and a radiofreque'ricy oscillator circuit including thespace current path of the other of said tubes in series with the second-z aryoi 'said'transformer, the-direction of said dis- I charge being' such, that a positive potential is impressed upon the anode of s'aidother tub ing said discharge, 7

'8. A system f duration of each train, said system 'comprising'at least a pair of electron tubes having their space=' current paths oppositely connected, respectively; relative to ground, a wave transmitter including T one tube, said transmitter being tuned to the anode, and a. grid, said grid beingl'c'onnected to a -source of control potential, 'said ano'de being period ofsaid cycles, said one tube having insuf iicient potential normally applied to the terminals I thereof to enable said transmitter to operate, an

energy storage network, a first circuit controlled by the other tubeto intermittently charge said storage network, :a second circuit controlled by said other tube to alternately discharge said storage network, and fmeans in said second circuit responsive to eachdischarge to intermittently in- I transmitting spaced wave trains, each train comprising a plurality of cycles having aperiod which is a minor'fraction of the crease said potential and render said transmitter operative during each discharge circuit.

9. A system as set forth in claim 8, wherein said last-named means comprises a transformer having its primary coupled to said second circuit and its secondary coupled to the space-current path of said one tube.

10. A system for transmitting spaced wave trains, each train comprising a plurality of cycles of a frequency which is considerably higher than the repetition rate of said wave trains, said system comprising at least a pair of electron tubes having their space current paths oppositely connected, respectively, relative to ground, an oscillator including one tube, said oscillator being tuned to said frequency, said one tube having zero potential applied to the terminals thereof, whereby said oscillator is normally inoperative, an energy storage network, means including the other tube to periodically charge said storage network externally of said one tube and to alternately discharge said storage circuit, and means excited by each discharge to intermittently apply suflicient potential to said one tube to render said oscillator operative during each discharge.

11. A system as set forth in claim 10, wherein said last-named means comprises a transformer having its primary coupled to said storage network and its secondary in series with the spacecurrent path of said one tube.

12. A system for transmitting spaced wave trains, each train comprising a plurality of cycles having a period which is a minor fraction of the duration of each train, said system comprising at least a pair of electron tubes having their spacecurrent paths oppositely connected, respectively, relative to ground, a radio-wave transmitter including one tube, said transmitter being tuned to the period of said cycles, said one tube having zero potential normally applied to the electrodes thereof, whereby said transmitter is normally inoperative, a storage condenser, a first circuit controlled by the other tube to periodically charge said storage condenser externally of said one tube, a second circuit controlled by said other tube to alternately discharge said storage condenser circuit through said one tube in such direction as to intermittently render said transmitter operative during each discharge.

13. A system as set forth in claim 12, wherein said other tube is of the arc-discharge type, and a source of keying oscillations to alternately render it conducting and nonconducting.

14. A system for transmitting intermittent wave trains, each train comprising a plurality of cycles of a frequency which is considerably higher than the repetition rate of said wave trains, said system comprising at least a pair of electron tubes having their space-current paths oppositely connected, respectively, relative to ground, a transmitting oscillator including one tube, said oscillator being tuned to said frequency, said one tube having zero potential normally applied to the anode thereof, whereby said oscillator is normally inoperative, an energy storage network, means controlled by the other tube to periodically charge said storage circuit externally of said one tube and to alternately discharge said storage condenser circuit through both tubes, whereby said oscillator oscillates during each discharge of said storage network.

JAMES R. MOORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,695,042 Fearing Dec. 11, 1928 1,837,144 Bethenod Dec. 15, 1931 2,137,251 Schlesinger Nov. 22, 1938 2,181,568 Kotowski Nov. 28, 1939 2,231,591 Pieplow -1 Feb. 11, 1941 2,276,994 Milinowski Mar. 17, 1942 2,295,585 Lindquist Sept. 15, 1942

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