US2056607A - Sound and television receiver - Google Patents

Sound and television receiver Download PDF

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Publication number
US2056607A
US2056607A US732759A US73275934A US2056607A US 2056607 A US2056607 A US 2056607A US 732759 A US732759 A US 732759A US 73275934 A US73275934 A US 73275934A US 2056607 A US2056607 A US 2056607A
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Prior art keywords
tube
amplifier
signal
circuit
sound
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Expired - Lifetime
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US732759A
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English (en)
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Ralph S Holmes
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RCA Corp
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RCA Corp
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Priority to US732759A priority Critical patent/US2056607A/en
Priority to FR791663D priority patent/FR791663A/fr
Priority to NL44165D priority patent/NL44165C/xx
Priority to DER93671D priority patent/DE709505C/de
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Publication of US2056607A publication Critical patent/US2056607A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/50—Tuning indicators; Automatic tuning control
    • H04N5/505—Invisible or silent tuning
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/22—Automatic control in amplifiers having discharge tubes
    • H03G3/26—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise, e.g. squelch systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/60—Receiver circuitry for the reception of television signals according to analogue transmission standards for the sound signals

Definitions

  • My invention relates to radio receivers and particularly to receivers adapted to receive picture signals and sound signals simultaneously.
  • the receiver includes a picture translating device such as a cathode-ray tube and a sound translating device such as a loud speaker. It has been found that, in tuning one of these receivers from one station to another, some very unpleasant effects are encountered. One results from the sound channel of the receiver being tuned for an instant to the incoming picture signal so as to produce a noise in the loud speaker. Another results from the picture channel of the receiverbeingtuned to the lncoming sound signal for an instant so as to produce flashes of light on the fluorescent screen of the cathode-ray tube. Not only are these eects displeasing to a person operating the receiver, but they may result in injury to the apparatus, especially the cathode-ray tube.
  • An object of my invention is to provide an improved receiver for receiving picture and sound signals simultaneously.
  • an object of my invention is to provide a receiver for use in a system of the above-mentioned type in which the aforesaid undesirable effects are avoided.
  • a further object of my invention is to pro vide a picture and sound receiver which will make a signal visible or audible only when the receiver is tuned to two carrier waves.
  • ll employ a superheterodyne receiver having an intermediate frequency channel through which picture signals are supplied to a cathode-ray tube and having another intermediate frequency channel through which sound signals are sup-- plied to a loud speaker.
  • a noise suppressor circuit is provided which normally prevents signals from being impressed upon either the cathode-ray tube or the loud speaker.
  • the noise suppressor circuit is so connected to the intermediate frequency channels that, when signals of the proper amplitude appear in both channels, the suppressor is released.
  • I take vadvantage of the fact'that the frequency spacing between the carriers of the intermediate frequency signals is the same as the frequency spacing of the sound and picture carrier waves sent out from a transmitter.
  • the two intermediate frequency carriers are heterodyned in a detector or mixer tube and the resulting beat frequency current is utilized to release the noise suppressor.
  • an automatic volume control or A. V. C. circuit in each intermediate frequency channel.
  • Each A. V. C. circuit is so connected to a noise suppressor circuit that the suppressor will be released only when signals of sufiicient volume are being received in both channels.
  • Figure l is a diagram showing the frequency spacing of signals transmitted in a system of the above-described type and also showing certain selectivity characteristics of my improved receiver.
  • Fig. 2 is a diagram, similar to Fig. l, showing the frequency spacing of a modified transmitting system
  • Fig. 3 is a circuit diagram of an embodiment of my invention utilizing beat frequency control
  • Fig. Il is a circuit diagram of a modified form of the receiver shown in Fig. 3,
  • Figs. 5 and 6 are circuit diagrams of embodiments of my invention utilizing automatic volurne control circuits for actuating the noise suppressor.
  • Station No. 1 is represented as transmitting a picture signal on a 50,000 k. c. carrier, the picture signal side bands having a width of 1000 lr. c.
  • This same station transmits sound signals on a 51,500 k. o. carrier which may have a side band width of 10 k. c.
  • the curve I shows the selectivity characteristie of the picture channel in a receiver of the type described in the above-mentioned Carlson patent*'while the curve 3 shows the selectivity characteristic of the intermediate frequency sound channel in the same receiver.
  • the receiver is tuned towards station No. 2: It will be apparent that before the receiver is properly tuned, the sound channel will receive the signal from the picture carrier of station No. 2 while the picture channel will be tuned to the sound carrier of station No. 1. As the signal from station No. 2 on the adjacent channel will be weak because of its geographic location, the picture signal noise in the loud speaker may not be very disturbing. The sound signal from station No. 1, however, will be a strong signal and will appear on the fiuorescent screen of the cathode-ray tube as flashes of light which are annoying to an observer and which may injure the tube.
  • the two intermediate frequency channels of the receiver may supply signals to the loud speaker and cathode-ray tube only when the receiver is properly tuned to the picture and sound signals from a single transmitting station.
  • the selecting circuit has a pass range wide enough to permit the passage of both the picture and sound signals from a single transmitting station. At the same time the selectivity is sufficient to separate the signals from one transmitting station from those from a different station.
  • the variable condensers or other tuning elements of the selecting circuit and of the oscillator are connected to a Icommon control knob II to permit simultanelplate current is flowing therethrough.
  • 'intermediate frequency sound amplifier I 5 is tuned to 9,500 k. c.
  • the selecting circuits in both amplifiers are of the band-pass type, as indicated by the curves I and 3 in Figs. l and 2.
  • the output of the picture amplifier I3 is impressed upon an amplifier tube I1 which may be of the four-electrode type comprising a cathode I9, a control grid 2
  • 1 is impressed upon a second detector 21 which may be of the diode type whereby the picture signal appears across a resistor 29 in the diode circuit.
  • the picture signal appearing across resistor 29 includes the synchronizing impulses or signals.
  • the picture signal is impressed upon an amplifier 3
  • is applied to the control grid 33 and to the deflecting devices 34 and 35 of a cathode-ray receiver tube 36.
  • the tube illustrated is of the type having a first anode 31, a second anode 39 and a fluorescent screen 4
  • the output of the sound amplifier I5 is im'- pressed upon an amplifier tube 43 which may be of the screen grid type comprising a cathode 45, a control grid 41, a screen grid 49 and an anode 5
  • the sound signal appearing in the plate circuit of the amplifier tube 43 is impressed upon a second detector 53 which may be of the diode type whereby the sound signal appears across a resistor 55 in the diode circuit.
  • the sound signal is amplified by an amplifier 51 and supplied to a loud speaker 59.
  • the amplifier tubes 43 and I1 are normally so biased that they will not amplify a signal.
  • the circuit which maintains this high negative bias on the amplifier tubes comprises a vacuum tube 6
  • which will be more fully described hereinafter and which comprises an inductance coil 13 shunted by a condenser 15, is connected at its upper terminal to the rectifier electrode 69 while it is connected at its lower terminal through a resistor 11 to the cathode 63.
  • the control grid 65 is connected to the end of the resistor 11 which is connected to the lower terminal of the tuned circuit 1
  • is connected through a resistor 19 to ground while the anode 61 is connected to a suitable source of positive potential whereby there is a flow of plate current through the resistor 19 so long as the control grid 65 is not too negative with respect to the cathode 63.
  • the cathodes of the amplifier tubes 43 and I1 are connected through conductors 8
  • of these tubes are put at a negative potential with respect to their cathodes since they are connected to ground through their tuned input circuits.
  • the circuit is so adjusted that when the grid 06 of the noise suppressor tube- 0
  • the release of the suppressor is effected in response to signals appearing in both the sound amplifier I5 and picture amplifier I3 by means of a mixer or detector tube 85 which comprises a cathode 81, a control grid 99, a second control grid 9
  • the cathode 81 is connected to ground through a source of biasing potential such as a. battery 91 whereby the control grids 89 and 9
  • the control grid 89 is connected through a coupling condenser
  • the anode 95 of the mixer tube is supplied with positive potential from a suitable source through a tuned circuit I I which is coupled to the tuned input circuit 1I of the noise suppressor tube 6
  • form a circuit which is sharply tuned to 1500 k. c.,
  • the grid 65 of the suppressor tube is made so negative that the current flow through the plate resistor 19 is greatly reduced whereby the high negative bias is removed from the control grids 2
  • the sound signal or the picture signal arriving at a receiver from a transmitter may be weak or of poor quality while the other signal from that transmitter is of good quality.
  • a station may transmit a picture signal unaccompanied by a sound signal or vice versa. Therefore, in order that a single signal may be received from a transmitter it is desirable that means be provided for making the suppressor circuit of the receiver inoperative at will.
  • this may be accomplished by ⁇ providing a switch 92 in the plate circuit of the suppressor tube 8
  • the receiver will normally be operated with the switch 92 closed. If it is known that a certain station should be transmitting a program which may be either a picture or sound alone, the receiver will be tuned to that station while the switch 92 is closed. Then the switch 92 will be opened to permit reception of the single signal.
  • the suppressor for the receiver shown in Fig. 6 may be rendered ineffective by opening a switch 288 in the plate circuit of the suppressor tube 219.
  • Fig. 4 there is shown a modification of the circuit shown in Fig. 3.
  • like parts are indicated by the same reference numerals.
  • the difference between the two circuits is the manner in which the control or biasing voltageis supplied from the noise suppressor tube 6I to the amplifier tubes 49 and I1.
  • the cathodes 45 and I9 of the amplifier tubes 43 and I1 are connected to ground while the control grids 41 and 2
  • 23 is included in the plate circuit of the noise suppressor tube 6
  • the operation of the circuit is substantially the same as that of the circuit shown in Fig. 3. If one of the intermediate frequency amplifier channels is not receiving signal energy, no beat note appears in the output circuit of the mixer tube 85 and the flow of current through the biasing resistor
  • FIG. 5 there is shown an embodiment of my invention in which a noise suppressor circuit is controlled by means of automatic volume control circuits.
  • the radio frequency amplifier or selecting circuit, the first detector, and the oscillator superheterodyne receiver are indicated at
  • the output circuit of the first detector is coupled to the input circuit of an intermediate frequency sound ampliner 33 through a secondary winding
  • each intermediate frequency amplifier is shown.
  • 33 includes the secondary winding
  • 43 is maintained at a positive potential with respect to ground by means of a self biasing resistor
  • 43, as well as the gain of other intermediate frequency amplifier tubes (not shown), is controlled automatlcally by varying the bias on its control grid
  • 33 is coupled through a tuned intermediate frequency transformer
  • 59 may be of the screen grid type having its cathode
  • the second detector ISI is of the diode type and includes in its circuit a resistor
  • 39 is similar to the sound amplifier and includes a first amplifier tube
  • 19 of this amplifiertube, as well as the control grids of other intermediate frequency (not shown), is connected through a conductor
  • 39 is coupled through a tuned intermediate frequency transformer
  • 89 may be of the diode type having a resistor
  • the automatic volume control circuit for the sound channel comprises the amplifier tube
  • 55 also includes a rectifier electrode 20
  • 93 is held positive with respect to ground by means of a self-biasing resistor 203 which is shunted by a suitable by-pass condenser 205.
  • 95 is connected through a resistor 201 to a point on the self-biasing resistor 203 for maintaining the tube
  • the upper portion of the selfbiasing resistor 203 is preferably shunted by another by-pass condenser 209.
  • 91 are supplied with positive potentials from any suitable source.
  • 55 is coupled through a coupling condenser 2
  • the rectifier circuit which includes a resistor 2
  • the A. V. C. circuit for the picture channel is the same as the A. V. C. circuit described above and includes the amplifier tube
  • the circuit of the rectifier section includes a resistor 229 which is so connected that its upper end becomes increasingly negative as the strength of the picture signal increases.
  • from the control grids of the intermediate frequency amplifier tubes is connected through a filter resistor 23
  • the sound channel is provided with a noise suppressor tube 233 while the picture channel is provided with a noise suppressor tube 235.
  • 'I'he noise suppressor tubes may be of the screen grid type.
  • the tube 233 comprises a cathode 231, a control grid 239, a screen grid 24
  • the control grid 239 is connected through a filter resistor 245 to the upper end of the volume control resistor 2
  • the cathode 231 may be connected to ground through a battery 241 or another source of biasing potential for maintaining the cathode negative with respect to ground for providing the desired delay in the noise suppressor action.
  • a filter condenser 249 is connected between the grid end of the filter resistor 245 and ground.
  • the control grid 239 Since the bias voltage supplied by the battery 241 opposes the voltage drop across the volume control resi'stor 2
  • 59 is connected through the conductor
  • 'I'he usual filter condenser 255 is connected between the grid end of the filter resistor 253 and ground.
  • the noise suppressor circuit is the same as .that in the sound channel.
  • the input circuit of the tube 235 is connected across the volumel control resistor 229 whereby the tube 235 is biased approximately to cut-a when an incoming signal reaches a predetermined amplitude. Until the signal reaches this amplitude, current flows in the plate circuit of the tube 235 through the plate resistor 250 which is common to the plate circuits of both suppressor tubes. Likewise, both plate circuits are supplied with plate voltage from the same alternating current source.
  • 81 is connected through the secondary of transformer
  • the suppressor circuit is so adjusted that if the resistor 259 has plate current flowing therethrough from either the suppressor tube 233 or the suppressor tube 235, both amplier tube
  • the suppressor tubes 233 and 235 should hav their voltages adjusted to give quicker cut-or than the intermediate frequency amplifier 'tubes which are controlled directly from the A. V. C. circuit. It has been found that RCA-57 type tubes are satisfactory as suppressor tubes when RCA-58 type tubes are being used as the intermediate frequency amplier tubes.
  • the transformers 213 and 221 may be tuned to have an over-al1 selectivity (together with .the preceding tuned transformers) shown by the curves 259 and 258, respectively, in Figs. 1 and 2. In some cases it may be preferred to tune the transformers 2
  • Fig. 6 I have shown a simplified form of noisesuppressor circuit in which the A. V. C. action is utilized.
  • Figs. 5 and 6 like parts are indicated by the same reference numerals.
  • 89 are coupled directly to the output circuits of the amplifiers
  • are supplied through a coupling condenser 259 to the input circuit of an audio frequency amplifier tube 26
  • the tube may be of the three electrode type comprising a cathode 263, a control grid 265, and a plate 261.
  • in the second detector circuit are supplied through a coupling condenser 289 to a picture amplifier tube 21
  • Signals are prevented from appearing at the loud speaker and cathode-ray tube by biasing the 4grids of the sound amplifier tube 26
  • a circuit comprising a suppressor tube 219 which functions as two separate amplifier tubes. It includes one set of electrodes consisting of a cathode 28
  • the cathodes 281 and 291 are connected to ground while the anodes 285 and 29
  • the plate circuit of the tube 219 includes a resistor 295 for supplying the control bias to the audio amplifier tube 26E and picture amplier tube 21i.
  • the control electrode 289 of the tube 219 is connected through a lter resistor 291 tothat end of the second detector resistor
  • the other control grid. 283 of the tube 219 is connected through a filter resistor 299 to that end of the second detector resistor 191 lwhich supplies A. V. C. bias for the tubes in amplifier 139. It will be seen that if there is no signal in one of the signal channels, one of the control grids of the suppressor tube 219 will be substantially at ground potential whereby there will be a flow of plate current through the plate resistor 295 to so bias the amplifier tubes 251 and 2li that they are ineffective to amplify a signal.
  • the sound signal will cause a high negative bias to be put on the control grid 299 of the noise suppressory tube 219 while the picture signal will cause a high negative bias to be put on the other control grid 283 of the noise suppressor tube 219 and the'iiow of current through the plate resistor vso 295 will be so reduced in value that the amplifier tubes 28
  • a radio receiver for the simultaneous reception of two carrier waves, each of which is modulated by a different signal, two translating devices, and means responsive only to the reception of both of said carrier waves for impressing one of said signals upon one of said translating devices.
  • a receiver according to claim 1 characterized in that one of said translating devices is a loud speaker and the other translating device a cathode-ray tube.
  • a radio receiver for receiving simultaneously two modulated carrier waves having a predetermined frequency spacing, a tunable selecting circuit, two translating devices, means for demodulating said carrier waves whereby two signals are produced, circuit connections between said demodulating devices and said translating devices whereby one of said signals mayA be impressed upon one of said translating devices and the other of said signals may be impressed upon the other of said translating devices, and means responsive only to the reception of both of said carrier waves for impressing one of said ⁇ signals upon one of said translating devices.
  • a tunable selecting circuit for demodulating said carrier waves to produce a picture signal and a sound signal, means whereby said picture signal and said sound signal may be impressed upon said cathode-ray tube and loud speaker, respectively and means responsive only to the reception of both of said carrier waves for impressing one of said signals upon said loud speaker.
  • a radio receiver comprising a radio frequency selecting circuit adapted to select a. plurality of modulated carrier waves, means for heterodyning said carrier waves to a plurality of intermediate frequency signals, means for demodulating one of said intermediate frequency signals to produce a certain signal, means for impressing said certain signal upon a translating device, means for demodulating another of said intermediate frequency signals to produce a different signal, means for impressing said diiIerent signal upon a second translating device, and means for preventing either saidcertain signal or said different signal from being impressed upon said translating devices so long as said selecting circuit is not tuned to a plurality of said carrier waves.
  • a receiver according to claim 5 characterized in that means is provided for making said last means ineffective at the will of the operator.
  • a plurality of translating devices means for heterodyning one of said carrier waves with the other of said carrier waves to produce a beat frequency, and means responsive to the production of said beat frequency I for impressing said signals upon said translating devic.
  • a receiver according to claim 7 characterized in that one of said translating devices is a cathode-ray tube for the reception of picture signals.
  • a receiver for the simultaneous reception of two carrier waves, at least one of which is modulated by a signal, means for heterodyning said carrier waves to two intermediate frequency signals.
  • a receiver according to claim 9 characterized 'in that said signal is supplied to said translating device through an amplifier, and further characterized in that said last means includes means for maintaining said amplifier substantially ineffective to amplify so long as said beat frequency is not being produced.
  • a receiver for the reception of at least two carrier waves, each modulated by a signal, means for selecting said carrier waves, means for converting said modulatedvcarrier waves to intermediate frequency signals, an amplifier tuned to one of said intermediate frequency signals, an amplifier tuned to another of said intermediate frequency signals, a plurality of translating devices, means for transferring signal energy from one of said amplifiers to one of said translating devices, means for transferring signal energy from said second amplifier to another of said translating devices, and means for making said two last-named means ineffective in response to the signal strength in either, of'said amplifiers falling below a predetermined value.
  • a receiver according to claim 11 characterized in that one of said amplifiers is tuned comparatively sharply to receive sound signals while the second of said amplifiers is tuned comparatively broadly to receive picture signals, and further characterized in that said one translating device is a loud speaker while said. second translating device is a cathode-ray tube.
  • a receiver comprising a broadly tuned radio frequency selecting circuit, a heterodyne oscillator and detector, a sharply tuned intermediate frequency amplifier, a broadly tuned intermediate frequency ampliiier, an automatic volume control operating in conjunction with each intermediate amplifier in such a manner that the output of each amplifier remains substantially constant under proper receiving conditions, and means controlled by both automatic volume controls for rendering a subsequent amplifier tube in each channel inoperative when a signal of insufiicient strength to operate the automatic monaco? volume controls is impressed upon either intermediate amplifier.
  • a receiver comprising a broadly tuned radio frequency selecting circuit, a heterodyne oscillator and detector, a sharply tuned intermediate frequency amplifier, an automatic volume control operating in conjunction with said intermediate frequency amplier to maintain its output substantially constant when a'signal of sutilcient intensity is being received, a second intermediate frequency amplier having a relatively broad selectivity characteristic tuned to a slightly dfferent frequency than the first intermediate amplier, an automatic volume control operating in conjunction with the second' intermediate frequency amplifier to maintain its output substantially constant when a signal o!
  • said second automatic volume control having a selectivity characteristic such that it will operate over only a substantially small band of the frequenciesv passed by the second intermediate amplifier, a demodulating device following each intermediate amplifier, an amplifier following each demodulator, a utilization device folowing each of the last mentioned apliers, and means responsive to the outputs of both automatic volume controls for preventing any signal voltage from reaching either utilization device when a signal of insufficient strength or of improper frequency to operate the automatic volume controls is impressed upon either intermediate frequency amplifier.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Television Receiver Circuits (AREA)
US732759A 1934-06-28 1934-06-28 Sound and television receiver Expired - Lifetime US2056607A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US732759A US2056607A (en) 1934-06-28 1934-06-28 Sound and television receiver
FR791663D FR791663A (fr) 1934-06-28 1935-06-24 Perfectionnements aux récepteurs de télévision
NL44165D NL44165C (de) 1934-06-28 1935-06-27
DER93671D DE709505C (de) 1934-06-28 1935-06-28 Empfaenger fuer Fernsehsendungen mit Tonbegleitung

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US732759A US2056607A (en) 1934-06-28 1934-06-28 Sound and television receiver

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US2056607A true US2056607A (en) 1936-10-06

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US732759A Expired - Lifetime US2056607A (en) 1934-06-28 1934-06-28 Sound and television receiver

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DE (1) DE709505C (de)
FR (1) FR791663A (de)
NL (1) NL44165C (de)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2448908A (en) * 1944-07-13 1948-09-07 Louis W Parker Television receiver
US2498488A (en) * 1946-06-14 1950-02-21 Gen Electric Television intercarrier or sound receiver circuit
US2504662A (en) * 1946-06-26 1950-04-18 Gen Electric Intercarrier television receiver circuit
US2505843A (en) * 1945-06-04 1950-05-02 Philco Corp Television receiver
US2516889A (en) * 1939-06-03 1950-08-01 Standard Telephones Cables Ltd Converter system
US2538040A (en) * 1943-05-01 1951-01-16 Arthur C Prichard Interference reduction circuit for radio pulse receivers
US2562703A (en) * 1947-12-26 1951-07-31 Gen Electric Multiple channel radio receiving system
US2580903A (en) * 1947-06-02 1952-01-01 Rca Corp Color television system
US2602855A (en) * 1950-09-30 1952-07-08 Avco Mfg Corp Television receiver squelching circuit
US2632800A (en) * 1949-03-26 1953-03-24 Motorola Inc Noise squelch system for television receivers
US2684402A (en) * 1949-12-31 1954-07-20 Stromberg Carlson Co Dual-purpose carrier-wave receiver
US2700753A (en) * 1948-06-28 1955-01-25 Phillips Petroleum Co Method of and apparatus for seismic prospecting
US2744961A (en) * 1950-07-01 1956-05-08 Hartford Nat Bank & Trust Co Receiver for two amplitude-modulated waves
US2912490A (en) * 1953-11-06 1959-11-10 Louis W Parker Tuning indicator and muter for television receivers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE928473C (de) * 1951-04-05 1955-06-02 Blaupunkt Werke Gmbh Fernsehempfaenger

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2516889A (en) * 1939-06-03 1950-08-01 Standard Telephones Cables Ltd Converter system
US2538040A (en) * 1943-05-01 1951-01-16 Arthur C Prichard Interference reduction circuit for radio pulse receivers
DE970147C (de) * 1944-07-13 1958-08-21 Louis William Parker Fernsehempfaenger
US2448908A (en) * 1944-07-13 1948-09-07 Louis W Parker Television receiver
US2505843A (en) * 1945-06-04 1950-05-02 Philco Corp Television receiver
US2498488A (en) * 1946-06-14 1950-02-21 Gen Electric Television intercarrier or sound receiver circuit
US2504662A (en) * 1946-06-26 1950-04-18 Gen Electric Intercarrier television receiver circuit
US2580903A (en) * 1947-06-02 1952-01-01 Rca Corp Color television system
US2562703A (en) * 1947-12-26 1951-07-31 Gen Electric Multiple channel radio receiving system
US2700753A (en) * 1948-06-28 1955-01-25 Phillips Petroleum Co Method of and apparatus for seismic prospecting
US2632800A (en) * 1949-03-26 1953-03-24 Motorola Inc Noise squelch system for television receivers
US2684402A (en) * 1949-12-31 1954-07-20 Stromberg Carlson Co Dual-purpose carrier-wave receiver
US2744961A (en) * 1950-07-01 1956-05-08 Hartford Nat Bank & Trust Co Receiver for two amplitude-modulated waves
US2602855A (en) * 1950-09-30 1952-07-08 Avco Mfg Corp Television receiver squelching circuit
US2912490A (en) * 1953-11-06 1959-11-10 Louis W Parker Tuning indicator and muter for television receivers

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Publication number Publication date
FR791663A (fr) 1935-12-14
DE709505C (de) 1941-08-20
NL44165C (de) 1938-05-16

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