US2458760A - Crystal controlled frequency modulation system - Google Patents
Crystal controlled frequency modulation system Download PDFInfo
- Publication number
- US2458760A US2458760A US611186A US61118645A US2458760A US 2458760 A US2458760 A US 2458760A US 611186 A US611186 A US 611186A US 61118645 A US61118645 A US 61118645A US 2458760 A US2458760 A US 2458760A
- Authority
- US
- United States
- Prior art keywords
- circuit
- grid
- frequency
- cathode
- control
- 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
Links
- 239000013078 crystal Substances 0.000 title description 40
- 230000003213 activating effect Effects 0.000 description 6
- 230000035559 beat frequency Effects 0.000 description 6
- 238000005513 bias potential Methods 0.000 description 6
- 230000010355 oscillation Effects 0.000 description 6
- 230000001276 controlling effect Effects 0.000 description 5
- 238000004804 winding Methods 0.000 description 5
- 238000010276 construction Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000002459 sustained effect Effects 0.000 description 2
- 101100400378 Mus musculus Marveld2 gene Proteins 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/10—Angle modulation by means of variable impedance
Definitions
- My invention relates broadly to modulation systems, and more particularlyto an improved circuit arrangement for a crystal controlled frequency modulation system.
- One of the objects of my invention is to provide an improved circuit arrangement for a frequency modulation circuit which is extremely simple in construction and which has excellent fidelity of modulation.
- Another object of my invention is to provide a construction of frequency modulation system in which a minimum number of tubes are utilized for producing frequency modulations under control of amplitude modulations.
- Another object of my invention is to provide a circuit arrangement for modulating crystal controlled oscillator systems for developing oscillations which are impressed upon a mixer circuit for deriving a frequency modulated difference frequency with respect to the frequencies of the crystal controlled oscillator systems.
- Still another object of my invention is to provide a circuit arrangment for amplitude modulating a twin three electrode electron tube for producing frequency modulations of extremely high fidelity.
- FIG. 1 schematically illustrates a circuit arrangement embodying the modulation system of my invention
- Fig. 2 shows an application of a modified form of the circuit arrangement embodying my invention.
- My invention is directed to acircuit arrangement for obtaining frequency modulation with a simple mezzo-electric crystal controlled circuit.
- the advantages of my circuit are its extreme simplicity and the excellent fidelity of modulation.
- I provide a piezoelectric crystal controlled circuit in which an audio modulating voltage of small magnitude is arranged to vary the bias potential applied to the crystal controlled circuit in such manner that frequency deviation of the crystal is controlled With corresponding high fidelity of modulation of the circuit.
- two crystal controlled oscillator circuits of the type hereinbefore described are combined to produce wide band frequency modulation.
- Two piezoelectric crystals of different frequencies are modulated in opposite directions by the push-pull audio input circuit of an amplitude modulated system. The frequency deviation is doubled in the output of an associated mixer circuit.
- cathode bias potentiometers in the circuits of the two crystal controlled oscillators will determine the frequency deviation and the fidelity of modulation.
- modulation may vary with different tubes and piezoelectric crystals, and the circuits of my invention provide compensation for all such variations.
- Fig. 1 discloses a three electrode electron tube including a heater la, a cathode lb, a control grid lo, and an anode id.
- the grid lc and cathode to are connectedthrough a high impedance circuit designated as 2, as including a resistor 3 and shunt connected condenser 4.
- the resistor and condenser combination are con nected into the cathode circuit through the bias resistor 5 shunted by condenser 6.
- the bias resistor 5 has an adjustable tap l movable thereover for rendering a selected portion thereof ineffective for controlling the bias potential supplied to the control grid lc. Suitable means are provided for activating cathode la.
- the anode Id is energized from a suitable potential source connected to terminals 8 through radio frequency choke coil 9.
- a piezoelectric crystal In is connected across control grid to and plate Id.
- An output circuit II is connected between plate Id and cathode lb, comprising as shown, the capacity l2 and resistor [4.
- An audio frequency control circuit I5 is connected across a portion of the high impedance circuit, accomplished by providing an adjustable tap E6 on high resistance 3 and connecting the adjustable tap to one side of the. audio frequency control circuit, where the other side of the audio frequency control circuit connects to the end of the resistance 3 as represented at H.
- Oscillations at the frequency of piezo-electric crystal ID are sustained in the electron tube circuit including the high impedance path 2. These oscillations are modulated by the audio frequency variations impressed through circuit I5 across a portion of high impedance circuit 2 which varies the bias potential on control grid lo and ole-- velops frequency modulations in the output circuit ll.
- Output circuit it connects to harmonic multipliers and power amplifiers of a frequency modulation system.
- the effective energy developed by the piezoelectric crystal lfl deviates in frequency as the load varies in the high impedance circuit 2, thus the audio frequency variations impressed through circuit I5 directly control the deviation in frequency of piezoelectric crystal I0 and develops frequency modulations in the output circuit II.
- Fig. 2 I have shown a system in which a high degree of precision is obtained in wide band frequency modulation.
- I employ a twin three electrode electron tube represented at I8, containing two sets of electrodes indicated at I9 and 26.
- the set of electrodes I9 is constituted by heater 19a, cathode I91), control grid I90, and anode
- the set of electrodes 20 includes heater 20a, cathode 2%, control grid 29c, and anode 20d. Suitable means are provided for activating cathodes
- 9d and 26d are energized from a suitable potential source connected to terminals 2
- the input circuits for each of the twin sets of electrodes are both of high impedance represented at 24 and 25.
- the input circuit 24 includes high resistance 26 shunted by condenser 27 and connected to the control grid I90 and cathode
- the bias control circuit 28 includes high resistance 29 shunted by condenser 36. The effective value of resistance 29 is controlled by movement of an adjustable tap 3
- the high impedance input circuit 25 consists of high resistance 32 shunted by condenser 33 and connected at one end to control grid 26c and at the other end to cathode 20b through the bias control circuit 34, which contains high resistance 35 shunted by condenser 36.
- An adjustable tap 3'! on resistance 35 controls the effective value of resistance 35 for correspondingly controlling the bias potential on control grid 200.
- Piezo-electric crystal 38 connects between'control grid I90 and anode I9d.
- Piezo-electric crystal 39 connects between control grid 20c and anode 26d. These crystals are of different frequencies, displaced from each other in the frequency spectrum to provide for a beat frequency therebetween. The crystal frequencies are modulated in opposite directions by a push-pull audio frequency input. I have illustrated the modulation circuit as including an audio frequency input at transformer 40, having a primary winding 4
- the secondary winding 42 has a central tap 43 connected to an intermediate point 44 between the cathodes I91) and 2% through the bias control circuits thereof.
- the opposite ends of secondary winding 42 are connected to adjustable taps 45 and 46 which are adjustable along high resistances 26 and 32.
- adjustable taps 45 and 46 are adjustable along high resistances 26 and 32.
- Circuits 24 and 25 are aperiodic in character and oscillations are sustained through the electron discharge paths across the respective sets of electrodes I9 and 20, at frequencies corresponding to the frequencies of piezo-electric crystals 38 and 39. These oscillations are impressed upon a mixer circuit which consists of pentagrid tube 41 having a heater 41a, a cathode 411), a pair of control grids 41c and 41d, an output grid 416, a space charge grid 41 and a plate 419.
- the anodes of the oscillator tube I8 at I? and 20d are respectively connected to control grids 41b and 41c through coupling condensers 48 and 49.
- the cathode 41b is connected through bias control circuit 50 with the opposite end of the output circuit of the oscillator tube I8.
- the mixer tube 41 has a tank circuit 5
- is disposed in the output circuit of tube 41 in circuit with high potential source connected with terminals 53.
- the output grid 41c has condensers 54 and 55 connected in circuit therewith on opposite sides of high impedance '52 and leading to the cathode side of the mixer tube.
- An output circuit is connected to the circuit 5
- a frequency modulation system comprising a twin three electrode tube, including sets of cathode grid and plate elements, means for activating. said cathodes, means for energizing said plates, a high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo electric crystals being displaced in frequency for producing a beat frequency therebetween, a tap in each of the high impedance paths associated with said grid and cathode elements, an audio frequency control circuit connected between said taps and to a point intermediate said cathode elements and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid, an anode and a space charge grid, a tank circuit tuned to the difference frequency between the aforesaid piezoelectric crystals and connected between said output grid and said anode'and connections between said plate elements of said twin three electrode tube and the respective control
- a frequency modulation system comprising a twin three electrode tube, including sets of cathode grid and plate elements, means for activating said cathodes, means for energizing said plates;
- a high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo electric crystals being displaced in frequency for producing a beat frequency therebetween, a tap in each of the high impedance paths associated with said grid and cathode elements, an audio frequency control circuit connected between said taps and to a point intermediate said cathode elements and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid, an anode and a space charge grid, a tank circuit tuned to the difference frequency between the aforesaid piezo-electric crystals and connected between said output grid and said anode connections between said plate elements of said twin three electrode tube and the respective control grids, and a condenser disposed in series with each of said last mentioned connections and operating as capacity coupling members.
- a frequency modulation system comprising a twin three electrode tube including sets of cathode grid and plate elements, means for activating said cathodes, means for energizing said plates, a high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo electric crystals being displaced in frequency for producing a beat frequency therebetween, an adjustable tap in each of the high impedance paths associated with said grid and cathode ele ments, an audio frequency control adjustable circuit connected between said taps and to a point intermediate said cathode elements, and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid, an anode and a space: charge grid, a tank circuit tuned to the difference frequency between the aforesaid piezo-electric crystals and connected between said output grid and said anode and connections between said plate elements of said twin three electrode tube
- a frequency modulation system comprising a twin three electrode tube including sets of cathode grid and plate elements, means for activating said cathodes, means for energizing said plates, 3, high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo-elec'tric crystals being displaced in frequency for producing a beat frequency therebetween, a tap in each of the high impedance paths associated with said grid and cathode elements, an audio frequency control circuit connected between said taps and to a point intermediate said cathode elements, adjustable means for control ling the bias potential on each of said grid elements and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid and an anode, a tank circuit connected between said output grid and said anode, connections between the plate elements of said twin three electrode tube and the respective control grids of said pentagrid tube and means
Description
Jan. 11, 1949. 2,458,760
CRYSTAL CONTROLLED FREQUENCY MODULATION SYSTEM' W. M. A. ANDERSEN Filed Aug 17, 1945 IQQWSQ xhx v n Patented Jan. 11, 1949 CRYSTAL CONTROLLED FREQUENCY MODULATION SYSTEM Walther M. A, Andersen, Hartford, Conn., assignor to Crystal Research Laboratories, Incorporated, Hartford, Conn, a corporation of Connecticut Application August 17, 1945, Serial No. 611,186
4 Claims.
My invention relates broadly to modulation systems, and more particularlyto an improved circuit arrangement for a crystal controlled frequency modulation system.
One of the objects of my invention is to provide an improved circuit arrangement for a frequency modulation circuit which is extremely simple in construction and which has excellent fidelity of modulation.
Another object of my invention is to provide a construction of frequency modulation system in which a minimum number of tubes are utilized for producing frequency modulations under control of amplitude modulations.
Another object of my invention is to provide a circuit arrangement for modulating crystal controlled oscillator systems for developing oscillations which are impressed upon a mixer circuit for deriving a frequency modulated difference frequency with respect to the frequencies of the crystal controlled oscillator systems.
Still another object of my invention is to provide a circuit arrangment for amplitude modulating a twin three electrode electron tube for producing frequency modulations of extremely high fidelity. I
Other and further objects of my invention reside in a circuit arrangement for a frequency modulation system as set forth more fully in the specification hereinafter following in which Fig. 1 schematically illustrates a circuit arrangement embodying the modulation system of my invention, and Fig. 2 shows an application of a modified form of the circuit arrangement embodying my invention.
My invention is directed to acircuit arrangement for obtaining frequency modulation with a simple mezzo-electric crystal controlled circuit. The advantages of my circuit are its extreme simplicity and the excellent fidelity of modulation. I provide a piezoelectric crystal controlled circuit in which an audio modulating voltage of small magnitude is arranged to vary the bias potential applied to the crystal controlled circuit in such manner that frequency deviation of the crystal is controlled With corresponding high fidelity of modulation of the circuit. In one of the applications of the system of my invention two crystal controlled oscillator circuits of the type hereinbefore described are combined to produce wide band frequency modulation. Two piezoelectric crystals of different frequencies are modulated in opposite directions by the push-pull audio input circuit of an amplitude modulated system. The frequency deviation is doubled in the output of an associated mixer circuit. The adjustment of cathode bias potentiometers in the circuits of the two crystal controlled oscillators will determine the frequency deviation and the fidelity of modulation. Such modulation may vary with different tubes and piezoelectric crystals, and the circuits of my invention provide compensation for all such variations.
Referring to the drawings in detail reference character i, Fig. 1, discloses a three electrode electron tube including a heater la, a cathode lb, a control grid lo, and an anode id. The grid lc and cathode to are connectedthrough a high impedance circuit designated as 2, as including a resistor 3 and shunt connected condenser 4. The resistor and condenser combination are con nected into the cathode circuit through the bias resistor 5 shunted by condenser 6. The bias resistor 5 has an adjustable tap l movable thereover for rendering a selected portion thereof ineffective for controlling the bias potential supplied to the control grid lc. Suitable means are provided for activating cathode la. The anode Id is energized from a suitable potential source connected to terminals 8 through radio frequency choke coil 9. A piezoelectric crystal In is connected across control grid to and plate Id. An output circuit II is connected between plate Id and cathode lb, comprising as shown, the capacity l2 and resistor [4. An audio frequency control circuit I5 is connected across a portion of the high impedance circuit, accomplished by providing an adjustable tap E6 on high resistance 3 and connecting the adjustable tap to one side of the. audio frequency control circuit, where the other side of the audio frequency control circuit connects to the end of the resistance 3 as represented at H.
Oscillations at the frequency of piezo-electric crystal ID are sustained in the electron tube circuit including the high impedance path 2. These oscillations are modulated by the audio frequency variations impressed through circuit I5 across a portion of high impedance circuit 2 which varies the bias potential on control grid lo and ole-- velops frequency modulations in the output circuit ll. Output circuit it connects to harmonic multipliers and power amplifiers of a frequency modulation system.
The effective energy developed by the piezoelectric crystal lfl deviates in frequency as the load varies in the high impedance circuit 2, thus the audio frequency variations impressed through circuit I5 directly control the deviation in frequency of piezoelectric crystal I0 and develops frequency modulations in the output circuit II.
In Fig. 2 I have shown a system in which a high degree of precision is obtained in wide band frequency modulation. In this arrangement I employ a twin three electrode electron tube represented at I8, containing two sets of electrodes indicated at I9 and 26. The set of electrodes I9 is constituted by heater 19a, cathode I91), control grid I90, and anode |9d arranged in the order shown. The set of electrodes 20 includes heater 20a, cathode 2%, control grid 29c, and anode 20d. Suitable means are provided for activating cathodes |9a and 20a. The anodes |9d and 26d are energized from a suitable potential source connected to terminals 2| through radio frequency choke coils 22 and 23 respectively.
The input circuits for each of the twin sets of electrodes are both of high impedance represented at 24 and 25. The input circuit 24 includes high resistance 26 shunted by condenser 27 and connected to the control grid I90 and cathode |9b through the bias control circuit 28. The bias control circuit 28 includes high resistance 29 shunted by condenser 36. The effective value of resistance 29 is controlled by movement of an adjustable tap 3| along resistance 29, thereby controlling the potential applied to control grid I90.
The high impedance input circuit 25 consists of high resistance 32 shunted by condenser 33 and connected at one end to control grid 26c and at the other end to cathode 20b through the bias control circuit 34, which contains high resistance 35 shunted by condenser 36. An adjustable tap 3'! on resistance 35 controls the effective value of resistance 35 for correspondingly controlling the bias potential on control grid 200.
Two piezo- electric crystals 38 and 39 are employed in the oscillation system of my invention. Piezo-electric crystal 38 connects between'control grid I90 and anode I9d. Piezo-electric crystal 39 connects between control grid 20c and anode 26d. These crystals are of different frequencies, displaced from each other in the frequency spectrum to provide for a beat frequency therebetween. The crystal frequencies are modulated in opposite directions by a push-pull audio frequency input. I have illustrated the modulation circuit as including an audio frequency input at transformer 40, having a primary winding 4| connected to the audio frequency modulation circult, and a secondary winding 42 coupled thereto. The secondary winding 42 has a central tap 43 connected to an intermediate point 44 between the cathodes I91) and 2% through the bias control circuits thereof. The opposite ends of secondary winding 42 are connected to adjustable taps 45 and 46 which are adjustable along high resistances 26 and 32. Thus,'a portion of the high resistances 26 and 32 in the high impedance circuits 24 and 25 are rendered ineffective by short circuit between the ends which connect with the intermediate point 44 between the cathode circuits and the positions of the adjustable taps 45 and 46.
The mixer tube 41 has a tank circuit 5| connected across plate 41g and the output grid 41c thereof through impedance path 52 as shown. The tank circuit 5| is disposed in the output circuit of tube 41 in circuit with high potential source connected with terminals 53. The output grid 41c has condensers 54 and 55 connected in circuit therewith on opposite sides of high impedance '52 and leading to the cathode side of the mixer tube. An output circuit is connected to the circuit 5| as represented by condenser 56 and high impedance 5'! from which connections lead to harmonic multipliers and power amplifiers of a frequency modulation system.
In the circuit of Fig. 2 audio frequency variations impressed upon the primary winding 4| change the effective bias potential on control grids |9b and 2922, thereby controlling the effective energy developed by the piezo- electric crystals 38 and 39 and the impression thereof upon the mixer circuit 41. The output frequencies will deviate as the sum of the deviation of the two crystal oscillators. The frequency deviation is double in the output circuit 56-5'| of the mixer circuit of tube 41, the two frequencies from piezo crystals 33 and 39 producing a beat frequency in the electronic path in tube 41 deriving a stabilized frequency modulated signal in the output system 55-5'|.
I have found the circuits of my invention highly effective in operation and while I have disclosed my invention in certain preferred embodiments I realize that modifications may be made and I intend no limitations upon my invention other than may be imposed by the scope of the appended claims.
What I claim and desire to secure by Letters Patent of the United States is:
1. A frequency modulation system comprising a twin three electrode tube, including sets of cathode grid and plate elements, means for activating. said cathodes, means for energizing said plates, a high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo electric crystals being displaced in frequency for producing a beat frequency therebetween, a tap in each of the high impedance paths associated with said grid and cathode elements, an audio frequency control circuit connected between said taps and to a point intermediate said cathode elements and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid, an anode and a space charge grid, a tank circuit tuned to the difference frequency between the aforesaid piezoelectric crystals and connected between said output grid and said anode'and connections between said plate elements of said twin three electrode tube and the respective control grids.
2. A frequency modulation system comprising a twin three electrode tube, including sets of cathode grid and plate elements, means for activating said cathodes, means for energizing said plates;
a high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo electric crystals being displaced in frequency for producing a beat frequency therebetween, a tap in each of the high impedance paths associated with said grid and cathode elements, an audio frequency control circuit connected between said taps and to a point intermediate said cathode elements and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid, an anode and a space charge grid, a tank circuit tuned to the difference frequency between the aforesaid piezo-electric crystals and connected between said output grid and said anode connections between said plate elements of said twin three electrode tube and the respective control grids, and a condenser disposed in series with each of said last mentioned connections and operating as capacity coupling members.
3. A frequency modulation system comprising a twin three electrode tube including sets of cathode grid and plate elements, means for activating said cathodes, means for energizing said plates, a high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo electric crystals being displaced in frequency for producing a beat frequency therebetween, an adjustable tap in each of the high impedance paths associated with said grid and cathode ele ments, an audio frequency control adjustable circuit connected between said taps and to a point intermediate said cathode elements, and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid, an anode and a space: charge grid, a tank circuit tuned to the difference frequency between the aforesaid piezo-electric crystals and connected between said output grid and said anode and connections between said plate elements of said twin three electrode tube and the respective control grids 4. A frequency modulation system comprising a twin three electrode tube including sets of cathode grid and plate elements, means for activating said cathodes, means for energizing said plates, 3, high impedance path connected between the grid and cathode of each of said sets of elements, a piezo-electric crystal connected between the grid and plate of each of said sets of elements, said piezo-elec'tric crystals being displaced in frequency for producing a beat frequency therebetween, a tap in each of the high impedance paths associated with said grid and cathode elements, an audio frequency control circuit connected between said taps and to a point intermediate said cathode elements, adjustable means for control ling the bias potential on each of said grid elements and a mixer circuit comprising a pentagrid tube including a cathode, a pair of control grids, an output grid and an anode, a tank circuit connected between said output grid and said anode, connections between the plate elements of said twin three electrode tube and the respective control grids of said pentagrid tube and means in said tank circuit for adjustably tuning said tank circuit to the diiferenc'e frequency between the frequency of each of said piezo-electric crystals.
W'ALTHER M. A. ANDERSEN.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 40 2,309,083 Usselman Jan. 26, 1943 2,390,777 Cole Dec. 11, 1945
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US611186A US2458760A (en) | 1945-08-17 | 1945-08-17 | Crystal controlled frequency modulation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US611186A US2458760A (en) | 1945-08-17 | 1945-08-17 | Crystal controlled frequency modulation system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2458760A true US2458760A (en) | 1949-01-11 |
Family
ID=24447966
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US611186A Expired - Lifetime US2458760A (en) | 1945-08-17 | 1945-08-17 | Crystal controlled frequency modulation system |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2458760A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2526347A (en) * | 1947-09-30 | 1950-10-17 | Union Switch & Signal Co | Method of and means for producing frequency modulation |
| US2555711A (en) * | 1946-07-18 | 1951-06-05 | Us Television Mfg Corp | Signal generator |
| US2562575A (en) * | 1947-01-04 | 1951-07-31 | Emhart Mfg Co | Electronic device for measuring physical constants |
| US2705755A (en) * | 1950-01-28 | 1955-04-05 | Orville C Hall | Mixer circuit |
| US2747164A (en) * | 1952-11-18 | 1956-05-22 | Hughes Aircraft Co | Frequency modulation of crystal oscillator |
| US2844796A (en) * | 1955-01-04 | 1958-07-22 | British Telecomm Res Ltd | Phase-modulators |
| US2905040A (en) * | 1951-04-27 | 1959-09-22 | Hammond Organ Co | Method and apparatus for producing chorus effects in music |
| US2998573A (en) * | 1957-01-28 | 1961-08-29 | Rca Corp | Signal generator having an output linearly related to an input function |
| US3136949A (en) * | 1960-10-20 | 1964-06-09 | Motorola Inc | Speech modulation system utilizing two spaced frequencies |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2309083A (en) * | 1941-10-16 | 1943-01-26 | Rca Corp | Frequency modulator |
| US2390777A (en) * | 1942-03-10 | 1945-12-11 | Westinghouse Electric Corp | Frequency modulation system |
-
1945
- 1945-08-17 US US611186A patent/US2458760A/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2309083A (en) * | 1941-10-16 | 1943-01-26 | Rca Corp | Frequency modulator |
| US2390777A (en) * | 1942-03-10 | 1945-12-11 | Westinghouse Electric Corp | Frequency modulation system |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2555711A (en) * | 1946-07-18 | 1951-06-05 | Us Television Mfg Corp | Signal generator |
| US2562575A (en) * | 1947-01-04 | 1951-07-31 | Emhart Mfg Co | Electronic device for measuring physical constants |
| US2526347A (en) * | 1947-09-30 | 1950-10-17 | Union Switch & Signal Co | Method of and means for producing frequency modulation |
| US2705755A (en) * | 1950-01-28 | 1955-04-05 | Orville C Hall | Mixer circuit |
| US2905040A (en) * | 1951-04-27 | 1959-09-22 | Hammond Organ Co | Method and apparatus for producing chorus effects in music |
| US2747164A (en) * | 1952-11-18 | 1956-05-22 | Hughes Aircraft Co | Frequency modulation of crystal oscillator |
| US2844796A (en) * | 1955-01-04 | 1958-07-22 | British Telecomm Res Ltd | Phase-modulators |
| US2998573A (en) * | 1957-01-28 | 1961-08-29 | Rca Corp | Signal generator having an output linearly related to an input function |
| US3136949A (en) * | 1960-10-20 | 1964-06-09 | Motorola Inc | Speech modulation system utilizing two spaced frequencies |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2269417A (en) | Cathode-driven oscillator | |
| US2458760A (en) | Crystal controlled frequency modulation system | |
| US2356071A (en) | Multivibrator | |
| US2611873A (en) | Bridge oscillator | |
| US2425981A (en) | Balanced frequency discriminator | |
| US2430126A (en) | Phase modulation | |
| US2347458A (en) | Frequency modulation system | |
| US2463533A (en) | Electrical impedance matching apparatus | |
| US3436676A (en) | Broadband power amplifier | |
| US2043242A (en) | High frequency oscillator | |
| US2713665A (en) | Transistor modulator circuits | |
| US2292798A (en) | Oscillator circuit | |
| US2925562A (en) | Frequency modulated crystal oscillator circuit | |
| US2390777A (en) | Frequency modulation system | |
| US2509280A (en) | Cathode-driven oscillator | |
| US2031100A (en) | Oscillation generator | |
| US1840580A (en) | Crystal-controlled oscillator | |
| US2017712A (en) | Frequency determining means | |
| US2565842A (en) | Frequency stabilizing device for high-frequency oscillators | |
| US1923305A (en) | Signaling system | |
| US1945547A (en) | Oscillation generation | |
| US2036164A (en) | Phase modulation | |
| US2324282A (en) | Wave length modulation | |
| US2415773A (en) | Oscillation generator for low frequencies | |
| US3275950A (en) | Double sideband suppressed carrier balanced modulator circuit |