US2010131A - Amplifier - Google Patents

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Publication number
US2010131A
US2010131A US625922A US62592232A US2010131A US 2010131 A US2010131 A US 2010131A US 625922 A US625922 A US 625922A US 62592232 A US62592232 A US 62592232A US 2010131 A US2010131 A US 2010131A
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Prior art keywords
amplifier
control
frequency amplifier
selectivity
tube
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US625922A
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English (en)
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George L Beers
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RCA Corp
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RCA Corp
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Priority to US625922A priority Critical patent/US2010131A/en
Priority to FR758215D priority patent/FR758215A/fr
Priority to DER88459D priority patent/DE649952C/de
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Publication of US2010131A publication Critical patent/US2010131A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G5/00—Tone control or bandwidth control in amplifiers
    • H03G5/16—Automatic control
    • H03G5/24—Automatic control in frequency-selective amplifiers
    • H03G5/26—Automatic control in frequency-selective amplifiers having discharge tubes

Definitions

  • AMPLIFIER Filed July 29, 1952 AMPLIFIER OSCILL/l TOE lA/VE/VTC/E. GeorgeLJBeers,
  • the manual selectivity control preferably takes the form of a potentiometer connected in the plate circuit of the volume control tube and means are provided whereby, through adjustment of a slider associated with the potentiometer, the automatic volume-control action may be apportioned between certain selectivity control tubes and the thermionic amplifier tubes per se.
  • the second and third intermediate frequency amplifier tubes 9 and i i are coupled through a transformer iii, the primary and secondary windings of which are so tuned and the coupling between them so adjusted that the transformer efficiently passes a band of frequences 10 kilocycles above and below the chosen.
  • intermediate frequency The third intermediate frequency amplifier tube it is provided with a tuned output circuit 2! which is coupled in the manner just described to a tuned circuit 23 having an intermediate ground connection 25.
  • the terminals of the said tuned circuit 23 are, respectively, connected to the input electrodes of a plurality of individual intermediate frequency ampiifier tubes 2'! and 29, the output.
  • circuits of which are coupled, respectively, to the input circuits of a plurality of second detector tubes 3! and 33.
  • the transformers connecting the fourth into the corresponding detector tubes 3i and 33 are also of the tuned and band-pass type referred to above.
  • Each of the second detector'tubes 3i and 33 is provided with an outputresistor 35, the low potential ends of the resistors-being connected together mid to ground through a by-pass condenser. Audio potentials developed across the several resistors are impressed, through high and low pass filters 3'! and 39, upon individual high and low audio frequency amplifiers 4
  • each output resistor 35 is connected to its associated filter through an adjustable slider 4'! and, preferably, the two sliders are mechanically inter-connected for simultaneous operation.
  • a source of anode and grid biasing potentials (not shown) is supplied, across the output circuit of which is connected a resistor '39.
  • Plate potential for all of the tubes thus far described is provided by a common connection 5! extending to the positive end of the resistor 4s, a resistor 53 being provided between the said connection and the anodes of the first detector tube and the first intermediate frequency amplifier tube to reduce somewhat the voltage applied thereto.
  • the screen grids of the several tubes in the system' may be supplied with positive potential over a common conductor 55 either from a point on the resistor 49 slightly less positive than the point supplying anode potential thereto, or may be connected, as is the fourth intermediate frequency amplifier tube 2?, to the anode thereof over a bleeder resistor 57 from which the requisite positive potential is derived.
  • a common conductor 55 either from a point on the resistor 49 slightly less positive than the point supplying anode potential thereto, or may be connected, as is the fourth intermediate frequency amplifier tube 2?, to the anode thereof over a bleeder resistor 57 from which the requisite positive potential is derived.
  • the receiver shall be selective when operated to receive weak signals from distant stations and more broadly tuned when used for the reception of strong signals from nearby stations.
  • I provide carrier-amplitude responsive control devices that function to automatically correlate the selectivity and sensitivity of the receiver to the strength of the incoming signal to which it is tuned.
  • I provide manually operable means for shifting the automatic action from combined selectivity and sensitivity control to simple gain control and, concurrently therewith, for removing automatic control from the audio frequency amplifier and rendering a portion of it inactive to amplify signals.
  • I provide a volume control tube 59 of the equi-potential type having an anode, a control grid, an electronically active cathode, and a heater.
  • the grid of the automatic volume control tube is directly connected to the grid of the second detector tube 33 which supplies the low audio frequency amplifier 43 and, as willbeinoted from an inspec-.
  • the grid of the saiddetector tube is connected bywayof-a conductor 6
  • the anode circuit of the volume control'tube includes the slider 63 of. a potentiometer, the
  • Thepotentiometer resistance element 65 preferab1y,1has a resistance of 700,000 ohms, while the resistors 61 and 69 connected,lrespectively to the ends thereof haveeacha resistance of 100,000 ohms.
  • the automatic volume control tube is normally biased to substantially the cut-offpoint.
  • An incoming signal, therefo ewhen applied to the grid thereof from the input circuit of the second detector tube causes an increasein the anode 30 or output current, which current-traverses the resistors 61 and 65 connectedto the ends of the potentiometer element, and a variableportion of.
  • I provide a plurality of thermionic devices I5, 11, I9, and 8 I, the function the user. These devices are hercinaftergenerally referred to as selectivity controltubes, although they: have otherfunction's, as will be made clear.
  • the selectivity control tubes may be of the equipotential type, each having an anode, a control grid, a cathode, and a heater.
  • the anode circuit of the first selectivity control tube I5 is-connected in. shunt to the-input circuit of the radio frequency amplifier tube I.
  • the anode circuit of the second selectivity control tube 11 is connected in shunt to the input circuit of the first intermediate frequency amplifier tube I, the anode circult of the third selectivity control tube I9 is connected in shunt relation to the input circuit of the second intermediate frequency amplifier tube 9, while the anode circuit of the fourth selectivity control tube 8
  • the input circuits of the several tubes just enumerated are, respectively, isolated from the gridsof the said tubes by individual blocking condensers 83, I5, .81, and 89.
  • the input circuit of the radio frequency amplifier tube I, as well as those of the first and. second intermediate frequency amplifier tubes, are connected to the conductor 5
  • the first three selectivity control tubes are also supplied with anode potential from the conductor 5 I, as will be clear from an inspection of the drawing.
  • Plate potential for the fourth selectivity control tube 8I is supplied from a point on the main potential supply resistor over a connection 9
  • the impedances of these paths control the damping in the said circuits and also controlthe energy transfer from the antenna to the radio frequency, amplifier tube, between the first detector'and the first intermediate frequency amplifier tube, as well. as between the first and second intermediate frequency amplifier tubes.
  • the slider 63 is moved from the position designated B in the drawing toward the position A, whereby the drop in potential across the resistor 59,, by reason of space current in the automatic volume control tube 59, decreases and the drop across resistor I57 increases.
  • the grids of the first three selectivity control tubes are connected to a common conductor 95- and to the plate potential supply circuit of the fourth sclectivitycontrol tube BI at a point intermediate'between the resistor 93 and the transformer secondary Ill referred to above.
  • the bias on the grid of the fourth selectivity control tube 8! is such that, normally, in the absence of incoming signals, a substantial plate current flows therein, which current causes sufficient drop across the resistor 93, connected to the grids of the first three selectivity control tubes, that they are biased to substantially the cut-off point. In such event, keeping in mind ha ibeslider s t ward h s i Alin se ecsensitivity thereof.
  • tivity of the system is high and weak signals are met by maximum amplification.
  • the grid of the amplifier tube 27 connected to the high audio frequency amplifier system 3l'-4l is connected to the same resistor 93 which supplies bias to the first three selectivity control tubes.
  • the said amplifier tube In the sensi- "ve condition, therefore, when tuned to receive weak signals, the said amplifier tube is biased highly negatively and the output therefrom is low, thus causing the burden of second detection and audio frequency amplification to be handled by the second detector 33 feeding the low audio frequency amplifier 3943.
  • the high audio frequency system thus under control, beat-notes and background noise are substantially eliminated and the reception of signals from weak distant stations may be satisfactorily accomplished.
  • the selectivity of the system is high, as pointed out, insofar as the radio frequency amplifier stage and the first and second intermediate frequency amplifier stages are concerned, which is the desirable condition for weak signal reception to assist in the elimination of background noise and beat-note interference.
  • the plate current in the automatic volume control tube 59 increases and, if the slider is still adjusted toward the position A, a greater potential is developed across the resistor 61, which renders the grid of the fourth selectivity control tube SI more negative, to reduce the plate current therein and, consequently, to decrease the potential drop across the resistor 93 included in the output circuit thereof.
  • the impedances of the control tubes are reduced and the shunting effect of those tubes is increased, resulting in a broadening of the tuning of that portion of the receiver ahead of the third intermediate frequency amplifier and a decrease in the The dimnution of the shunting effect of the fourth selectivity control tube upon the input circuit of the third intermediate frequency amplifier tube increases the effec tive coupling between the second and third intermediate frequency tubes, thus increasing the fidelity of reproduction of the system during the reception of strong signals, though slightly offsetting the decreased sensitivity.
  • the resistor 93 is included in the circuit normally supplying cut-off bias to the amplifier tube 21 that feeds the detector 3
  • the potentiometer slider 63 may be adjusted toward position B. Such adjustment, since it deprives all of the selectivity control tubes of grid potentials proportional to incoming signal amplitude, causes the said tubes to relinquish,
  • the slider may be moved to the extreme B position, thus rendering the selectivity maximum and completely stopping the high audio frequency response of the receiver.
  • the potentiometer 6365 has an extremely important function. Through the use of the said potentiometer, the characteristics of the receiver may be altered in a smooth and continuousv manner.
  • the slider 63 When it is desired that the system shall be free of the objectionable interference phenomena hereinbefore referred to, the slider 63 is manually adjusted toward the position B and automatic volume control or gain control of conventional type is had on the radio frequency and intermediate frequency amplifier tubes and the high frequency portion of the audio frequency amplifier is rendered inoperative. On the other hand, when the reception of strong signals from nearby stations is desired, together with better fidelity of reproduction, provided no interference exists, the slider 63 is adjusted toward the position A, in which event automatic volume control is had through alteration of the characteristics of the intertube coupling devices and the high frequency portion of the audio frequency amplifier is permitted to function.
  • my invention is not limited to the specific circuit chosen for pur-- poses of illustration.
  • I may make use of a single channel amplifier, as is customary.
  • I provide a controllable high frequency path in shunt to the input circuit or the output circuit of the audio frequency amplifier, and control the impedance of the shunt from the automatic volume control tube which also controls the so-called selectivity control tubes.
  • the specific manner in which the shunt may be controlled is not a feature of my present invention, but the system disclosed in my copending application, Serial No. 545,704, filed June 20, 1931, and assigned to Radio Corporation of America, is one that has given entire satisfaction.
  • a thermionic tube the space current path of which is effectively connected in series with a high frequency shunt across the input circuit of the audio frequency amplifier and the grid bias applied to the tube is made a function of an incoming signal.
  • the grid of the shunting tube is connected to the junction between resistors 65 and 61, shown in the drawing. That is to say, the connections are such that, as the selectivity of the radio frequency portion is automatically increased during the reception of weak signals, the high frequency response of the audio frequency amplifier is reduced.
  • the automatic volume control tube'59 may be omitted from the system illustrated in the drawing and a variable resistor 96, shown in dotted lines, of," say 100,000 ohms, be connected, instead, betweenithe slider 63 and a point 9! on the resistor 49. If this isdone, the slider EB'may be utilized to determine the effect, simultaneously,'of the radio and audio portions on the overall fidelity while the resister 96 may be adjusted to control the sensitivity of the receiver.
  • My invention therefore; is not to be restricted except insofar as" is necessitated by the prior art and by the spirit of the appended claims.
  • sensitivity and selectivity control means In a radio receiver, sensitivity and selectivity control means, audio frequency fidelity-control. means, and means responsive to changes, in strength of incoming signals for automatically actuating each of said control means.
  • a radio frequency amplifying portion In a radio receiving system, a radio frequency amplifying portion, an audio frequency amplifying portion, means for' controlling the eifect of each portion on the overall fidlity and for simultaneously controlling the fidelity of the said portions.
  • a radio receiving syStem the combination of a radio frequency amplifying portion, an audio frequency amplifying portion, and means for concurrently controlling the effect of each portion on the overall fidelity, said means being responsive to incoming signals.
  • a radio fre quency amplifying portion In a radio receiving system, a radio fre quency amplifying portion, an audio "frequency amplifying portion, means for maintaining the effect of each portion on the overall fidelitysubstantially similar and for automatically controlling the fidelity of the said portions, and manually i operable means for determining the degree of automatic control applied to the said porti'ons, whereby the fidelity of reproduction may be adjusted during the reception of signals from strong local stations. 7 I i 7.
  • sensitivity and selectivity-control means In a radio receiver, combined sensitivity and selectivity-control means, audio-frequency fidel: ity control means, means responsive tochanges in strength of incoming signals for automatically actuating each of said control-means, and means for at will altering the measure of automatic con trol over the receiver characteristics enumerated, namely, over its sensitivity, selectivity, and audio frequency fidelity.
  • ity control means means responsive tochanges in strength of incoming signals for automatically actuating each of said control-means, and means for at will altering the measure of automatic con trol over the receiver characteristics enumerated, namely, over its sensitivity, selectivity, and audio frequency fidelity.
  • a radio receiver a pluralityof electric dis charge amplifier devices, coupling networks-between certain of said devices, automatic volume control means for roviding control-potentials for said amplifier devices means including ,.elec-. tric discharge devices controllable by said-auto- 9 matic volume control means having spacecurrent paths in shunt with certainof the coupling net works and manually operable meanslfor gradually applying said controlled potentials tosaidlast named means.
  • manually operable means for adjusting the measure of fidelity-control and means for concurrently altering the selectivity of the receiver whereby it may be placed in such operating condition that interference of the adjacent channel type is minimized.
  • a high frequency amplifienan audio frequency amplifier means for concurrently controlling each of said amplifiers, said'means being responsive to incomlng signals, and including an automatic volume control electric discharge device having an output circuit, a coupling impedance in said output circuit for applying'controlling potentials to said high frequency amplifier, an electric discharge amplifier device for controlling the damping and energy transfer through said high frequency amplifier and the fidelity characteristics of both of said amplifiers simultaneously, and manually controllable means for gradually connecting the output circuit of saidautomatic volume control device withsaid last named electric discharge control device for applying controlling potentials thereto in response to variations in signal strength.
  • a radio receiving system the combinationwith a high frequency amplifier and automatic volume control means comiected therewith, of an electric discharge device connected with said amplifier to control inter-stage coupling means therein, means connected with said amplifier to control the dampingand energy transfer therethrough, said last named means being connected with an'output circuit of said electric discharge control device, and means for gradually changing the automatic volume control connection from the amplifier to the input circuit of said electric discharge control device.
  • said first named amplifier of an electric discharge device connected with said first named amplifier to control inter-stage coupling mean -therein, means connected with said first named amplifier to control the damping and energy transfer therethrough,- said last named means being connected with an output circuit of said electric discharge control device, means for gradually changing the automatic volume control connection from the amplifier to the input circuit of said electric discharge control device, andmeans connected with the output circuit of said electric discharge control device for controlling the response characteristic of said audio frequency'amplifier.
  • a radio receiving system the combination with a high frequency amplifier, an audio frequency amplifier, and automatic volume control means connected therewith, of an electric discharge device connected with said amplifier to controlinter-stage coupling means therein, a plurality of electric discharge devices having anode circuits connected with said amplifier to control the damping and energy transfer there through, said last named devices having control electrodes connected with an output circuit of said electric discharge control device, and means for gradually changing the automatic volume control connection from the amplifier to the in put circuit of'said electric discharge control device.
  • a radio receiving system the combination with a high frequencyamplifier, an audio frequency amplifier, and automatic volume control means connected with said first named amplifier, of coupling means in said high frequency amplifier including a pair of coupled tuned circuits, an electric discharge device having a control electrode and having an output anode connected with one of said tuned circuits whereby the space current path thereof is substantially in shunt thereto, and means for connecting said automatic volume control means with the control electrode of said last named electric discharge device.
  • a radio receiving system the combination with a high frequency amplifier, an audio frequency amplifier, an automatic volume control means connected with said first named amplifier, of coupling means in said high frequency amplifier including a pair of coupled tuned circuits, an electric discharge device having a control electrode and an output anode connected with one of said tuned circuits whereby the space current path thereof is substantially in shunt thereto, an impedance device in circuit with said anode and means responsive to controlling potentials derived from said impedance device for controlling the damping and energy transfer through the circuits of said high frequency amplifier and the response characteristic of said audio frequency amplifier, an impedance device for coupling said automatic volume control means with the high frequency amplifier, a second impedance means for coupling said automatic volume control means with the control electrode of said last named electric discharge device, and a manually operable potentiometer means for selectively connecting said automatic volume control means with either of said last named impedance devices.
  • a signal amplifier including a plurality of electric discharge amplifier devices, means for connecting said devices in cascade relation, means providing an automatic bias control circuit for said devices, means for controlling the damping and energy transfer of signals between said amplifier devices including a tunable input circuit for one of said devices and an electric discharge device having its space current path connected substantially in parallel with said circuit, an automatic volume control device of the electric discharge type, said device being connected with the signal channel to receive controlling potentials therefrom, an impedance device in a control circuit for one of said last named devices, a second im- 1 pedance device in a sensitivity control circuit for said amplifier devices, and potentiometer means for gradually connecting said automatic volume control device selectively from one to the other of said impedance devices.
  • a radio signal receiving system the com bination of a plurality of electronic amplifier devices, coupling means between at least two of said devices comprising a pair of coupled tuned circuits, an electronic device providing a variable impedance in parallel with one of saidtuned circuits thereby to vary the selectivity of said system inversely with the impedance of said device, automatic volume control means for said electronic amplifier devices, a coupling network between said automatic volume control means and the said amplifier devices including a variable imtion with a high frequency amplifier, an audio frequency amplifier, and automatic volume control means for said first named amplifier, of an electric discharge device connected with said first named amplifier to control inter-stage coupling means therein, means for gradually changing the automatic volume control connection from the amplifier to the input circuit of said electric discharge control device, and means connected with the automatic volume control means for controlling the response characteristic of said audio frequency amplifier.
  • a radio receiving system the combination with a high frequency amplifier, an audio frequency amplifier, and automatic volume control means connected with said first named amplifier, of coupling means in said high frequency amplifier including a pair of coupled tuned signal circuits, an electric discharge device having a control electrode and an output anode connected with one of said tuned circuits whereby the space current path thereof is substantially in shunt thereto, means for connecting said automatic volume control means with the control electrode of said last named electric discharge device, and means responsive to said automatic volume control means when so connected for simultaneously controlling signals supplied to said audio frequency amplifier.
  • a radio receiving system the combination of a plurality of electronic amplifier devices, automatic means for controlling the gain in said amplifier devices, signal conveying coupling means between at least two of said devices, means for varying the selectivity of said coupling means including an electronic control device connected with said automatic gain controlling means, an audio frequency amplifier, means for applying signals from said first named amplifier devices to said last named amplifier, and means connected with and controlled by said automatic gain controlling means for controlling the audio frequency response characteristic of said last named amplifier.
  • a radio receiving system the combination of a plurality of electronic amplifier devices, coupling means for said amplifier devices, signal controlled means for deriving control potentials varying in opposite sense, means for utilizing said control potentials to vary the selectivity of at least two of said coupling means in the same sense, audio frequency amplifier means for said system, and means for utilizing one of said control potentials to vary the frequency characteristic of said last named amplifier means.
  • a radio receiving system the combination of a plurality of electronic amplifier devices, coupling means for said amplifier devices, signal controlled means for deriving control potentials varying in opposite sense, means for utilizing said control potentials to vary the selectivity of at least two of said coupling means in the same sense, means for utilizing one of said control potentials to vary the signal gain through said re DCving system, and additional means responsive to operation of said gain controlling means for varying the audio frequency output characteristic of said system.
  • a radio receiving system in combination with a signal amplifier, means for simultaneously varying the gain and selectivity of said amplifier in response to variations in signal strength, and additional means for varying 'the audio frequency output characteristic of said system connected with said first named means for simultaneous control thereby.
  • a radio receiving system the combination with a signal amplifier including a plurality of electronic amplifier devices, of means for simultaneously controlling the gain and selectivity of said amplifier in response to variations in signal strength, said means including a source of signal variable biasing potential for said amplifier devices, a signal variable impedance in shunt with the signal channel of said amplifier, means providing an audio frequency amplifier channel for receiving signals from said first named amplifier, and means for controlling the signal transmission through said channel in response to operation of said first named means.
  • a signal amplifier comprising a plurality of coupled tuned eiectronic amplifier stages, means responsive to variations in signal amplitude for simultaneously varying the tuning characteristic of certain of the stages of said amplifier and the effective coupling between at least two of said stages to vary the selectivity and the fidelity of said receiving system, and means simultaneously controllable with said last named means in response to signal amplitude variations for varying the audio frequency output characteristic of said system in accordance therewith.
  • a signal amplifier comprising a plurality of coupled tune-d electronic amplifier stages, means responsive to increased signal amplitude for simultaneously broadening the tuning of certain of the stages of said amplifier and increasing the effective coupling between at least two of said stages to increase the fidelity of response to said receiving system, audio frequency amplifier means for said system, and means for simultaneously increasing the fidelity of said audio frequency amplifier means in response to increased signal amplitude.
  • a signal amplifier comprising a plurality of coupled tuned electronic amplifier stages, means responsive to increased signal amplitude for simultaneously broadening the tuning of certain of the stages of said amplifier and increasing the effective coupling between at least two of said stages to increase the fidelity of response of said receiving system, audio frequency amplifier means for said system, means for simultaneously increasing the fidelity of said audio frequency amplifier means in response to increased signal amplitude, automatic volume control means for said signal amplifier, and. means providing a controllable connection between said automatic volume control means and said fidelity control means.
  • a radio receiving system the combination of a signal amplifier comprising a plurality of coupled tuned amplifier stages, automatic volume control means for applying variable gain controlling potentials to certain of the amplifier stages in response to variations in signal strength, means for simultaneously broadening the tuning of and increasing the coupling between certain of said amplifier stages in response to increased signal strength thereby to increase the fidelity and to decrease the selectivity of said signal amplifier, audio frequency amplifier means for said system, means for increasing the fidelity of response of said audio frequency amplifier means simultaneously with said first named means in response to increased signal strength, and means providing a variable control connection between said automatic volume control means and said first and last named means.
  • a signal amplifier comprising a plurality of coupled tuned electronic amplifier stages, an audio frequency amplifier, automatic volume control means for said first named amplifier and means controllable by said automatic volume control means for broadening the tuning of and increasing the coupling'between certain of the stages of said first named amplifier and simultaneously increasing the high frequency response characteristic of said audio frequency amplifier in response to increased signalstrength.
  • a signal amplifier comprising a plurality of tuned coupled signal circuits, a plurality of separate signal amplifier circuits having diifering audio frequency output characteristics, and means for simultaneously broadening the tuning of and the coupling between certain of the stages of said first named amplifier and the gain through one of said separate amplifier circuits in response to increases in the amplitude of received signals.
  • a superheterodyne radio receiving system the combination with an intermediate frequency amplifier and automatic volume control means therefor, of audio frequency amplifier means having a plurality of frequency discriminating channels, a separate intermediate. frequency amplifier for at least one of said channels, means for simultaneously broadening the tuning of and increasing the coupling between certain of the signal conveying circuits of said first named intermediate frequency amplifier, and increasing the gain through said last named intermediate frequency amplifier, and means providing an automatic volume control connection whereby said last named means is operable in response to an increase in the amplitude of received signals.

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  • Amplifiers (AREA)
US625922A 1932-07-29 1932-07-29 Amplifier Expired - Lifetime US2010131A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US625922A US2010131A (en) 1932-07-29 1932-07-29 Amplifier
FR758215D FR758215A (fr) 1932-07-29 1933-07-11 Perfectionnements aux appareils radio-récepteurs
DER88459D DE649952C (de) 1932-07-29 1933-07-30 Empfaenger mit selbsttaetiger Regelung der Trennschaerfe und Lautstaerke in Abhaengigkeit von der Traegerwellenamplitude

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US625922A US2010131A (en) 1932-07-29 1932-07-29 Amplifier

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US2010131A true US2010131A (en) 1935-08-06

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US625922A Expired - Lifetime US2010131A (en) 1932-07-29 1932-07-29 Amplifier

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DE (1) DE649952C (fr)
FR (1) FR758215A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2488612A (en) * 1940-03-09 1949-11-22 Rca Corp Frequency modulation reception
US2491331A (en) * 1939-02-09 1949-12-13 Plump Ernst Hermann Receiver for frequency-modulated waves
US2612558A (en) * 1946-08-13 1952-09-30 Paul W Klipsch Crossover filter network
CN103984012A (zh) * 2014-04-16 2014-08-13 孙赞东 基于叠前高斯束深度偏移的绕射波场分离方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2491331A (en) * 1939-02-09 1949-12-13 Plump Ernst Hermann Receiver for frequency-modulated waves
US2488612A (en) * 1940-03-09 1949-11-22 Rca Corp Frequency modulation reception
US2612558A (en) * 1946-08-13 1952-09-30 Paul W Klipsch Crossover filter network
CN103984012A (zh) * 2014-04-16 2014-08-13 孙赞东 基于叠前高斯束深度偏移的绕射波场分离方法

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Publication number Publication date
DE649952C (de) 1937-09-08
FR758215A (fr) 1934-01-12

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