US2282973A - Wide band frequency modulation receiving system - Google Patents
Wide band frequency modulation receiving system Download PDFInfo
- Publication number
- US2282973A US2282973A US343137A US34313740A US2282973A US 2282973 A US2282973 A US 2282973A US 343137 A US343137 A US 343137A US 34313740 A US34313740 A US 34313740A US 2282973 A US2282973 A US 2282973A
- Authority
- US
- United States
- Prior art keywords
- frequency
- signal
- amplifier
- modulation
- audio frequency
- 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
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
- H03D3/001—Details of arrangements applicable to more than one type of frequency demodulator
- H03D3/003—Arrangements for reducing frequency deviation, e.g. by negative frequency feedback
- H03D3/004—Arrangements for reducing frequency deviation, e.g. by negative frequency feedback wherein the demodulated signal is used for controlling an oscillator, e.g. the local oscillator
Definitions
- WIDE BAND FREQUENCY MODULATIN RECEIVING SYSTEM may a2, "1942.,
- This invention relates to wide band frequency modulation receiving systems, and has for .its
- the effective band width of the signal is altered -by feedback voltage control through the heterodyne oscillator to cause the intermediate frequency signal to be maintained at all times at a band width covering a major portion of the pass band width of the intermediate frequency .circuitsfor example, eighty percent of the band width, and to cause the intermediate frequency swing or signal band width to be maintained within the band ⁇ width limits ofthe Vintermediate ,frequency circuitsfor higher percentage modulation, without causing distortion of the audio ⁇ frequency output signal.
- anobject of the invention to provide ⁇ means 'whereby the audiov frequency amplification may be changed .automatically with variations in the modulation or signal frequency swing above .a predetermined value, preferably in the intermediate .frequency circuits, to secure the proper audio frequency output level and dy- -namic operating range -of the signal at the output circuit of the receiving system.
- IThisnox ⁇ plates that both the effective band Width of reception and the audio frequency gain in the system may be'controlled automatically in response to variations in anaudio vfrequency control volt- ⁇ age vas ⁇ a measureof the percentage modulation or frequency swing, thereby Ytopermit ythe effective band width to vary without audio frequency distortion.
- While negative feedbackfcontrol of the oscillator frequency may be provided to narrow the signal band, it may be desirable with low modulation levels to utilize positive feedback to widenv the band of the signal to equal the pass band of the receiving system, in which'fcase the. audio frequency gain of the system should be correspondingly reduced to prevent distortion. 4
- Figure 1 is a schematic circuit diagram of a signal receiving system-embodying the invention.
- Figure 2 is a graph showing curves illustrating certain operating characteristics of the circuit of Fig. 1.
- the wide band frequency modulation receiving system shown comprises a wide band tunable r. f. or high frequency amplifier 5 coupled to a suitable signal source such y
- the amplifier stages I3 is a gain control amplifier stage which is preferably of the pentagrid type, having a signal input grid I6 coupled through a potentiometer I'I, and an impedance coupling network I8, to the output circuit I9 of the preceding amplier stage I2.
- a gain control grid is also provided in the tube I3 as part of a volume control or expander means to control amplitude of signals transmitted through the stage.
- Variable gain controlling potential for the grid 2U is derived througha control circuit 2
- the rectifier 23 and the associated circuits include a suitable source of fixed biasing potential 25 for the control grid 20 and a delay bias potential source 26 for the rectifier 23 effective to prevent response of the rectifier to signals below a certain value of applied signal potential corresponding to a certain percentage modulation or swing.
- the percentage modulation or frequency swing is determined by the audio frequency o'utput of' the receiving system a portion of which is applied to the rectifier 23 from the first stage audio frequency amplifier output circuit I9 through a supply lead21, a coupling capacitor 28 and an input potentiometer device 29.
- Audio frequency signals are also derived from the output circuit I9 through the potentiometer device I'I and a variable tap connection 3D thereon for a feedback control or variable gain amplifier stage 3
- is coupled through a suitable coupling capacitor 35 and a circuit 36 with frequency control means 31 connected with the oscillator 8 in proper phase relation to cause the oscillator frequency to Vary in synchronism with the incoming signal, above and below a normal frequency by an amount dependent upon the adjustment of the applied signal from the tap 30 and the bias control potential on the gain control grid 33 of the control amplifier 3
- the audio frequency output from the discrim- Vinator network I Il .through the second detector I I and amplifier I 2 to the tap 39 provides a measure of the percentage modulation or frequency swing of a received signal. This causes the feedback control amplier 3
- the oscillator may at the same time be caused to swing in frequency 1-75 kc., making a differential swing of 25 kc. in the i. f. amplifier signal for one hundred percent modulation. This tends to result in a reduction in theaudio frequency output which is compensated as will hereinafter be pointed out.
- the intermediate frequency amplifier may provide a relatively high gain and a relatively narrow frequency response, while the input circuit or r. f. amplifier may have a desired wide band characteristic. Then, assuming further a 40 mc. signal-modulated i100 kc. at one hundred percent modulation, and i2() kc. for a relatively low modulation of twenty percent, the intermediate frequency amplifier may be made substantially only 50 kc. wide.
- the effective band width of the signal is altered by feedback control through the heterodyne oscillator to provide an i. f. signal which occupies substantially eighty percent of the i. f. band. width with twenty percent modulation, for example, as indicated in connection with the output response curve 40 of the discriminator network and detector, ⁇ while the remaining veighty percent change in percentage modulation causes a relatively slight increase in the effective use of the full band width of the amplifier 9.
- signals of relatively low percentage modulation are caused to occupy a major portion of the band width of the signal channel, preferably in a narrow band high gain i. f. circuit and negative feedback voltage control to the oscillator is provided and controlled to a degree to preventthe signal swing from exceeding the limits of the pass band of the i. f. amplifier up to substantially full modulation.
- indicates the amplitude of the input andoutput signal of the gain control ampliiier stage I3 with relatively low frequency swing, such as, below twenty percent modulation, while the curve 42 indicates the vinput voltage with one hundred percent modulation and the resulting output signal voltage is indicated by the curve 43.
- This additional output is provided by the control rectifier 23 which causes an increasing positive bias on both grids 33 and 20 vand volume range expansion above 20 percent modulation in the present example.
- This action prevents distortion of the audio frequency output which would otherwise result from altering the effective modulation of the intermediate frequency signal by variation of the oscillator frequency and includes controlling the effective band width of reception through the i. f. amplier, with variations in swing of the signal and the gain of the audio frequency amplifier and feedback control path simultaneously, so that the output of the receiver faithfully follows the modulation changes above the predetermined low modulation level without exceeding the band width of' the amplifier. At one hundred percent modulation, substantially the entire band is used and the audio frequency gainis maximum.
- the rectifier 23. and its associated circuits have ⁇ a time constant which provides for a rapid response and slow recovery characteristic thereby insuring that the system will respond to but will Vnot follow the modulation frequency changes.
- both the amount of feedback and the audio frequency gain may automatically be controlled i from a rectifier operated by the audio voltages derived from the frequency modulation receiving system following the discriminator network, as a measure of the percentage modulation, thereby simultaneously making the effective band width of reception vary with the percentage modulation above a predetermined low percentage and compensating for'the effective reduction in the audio frequency signal amplitude from the detector by increasing the gain in both .the audio frequency and feedback control channels.
- a radio signal receiving system the combination with a signal amplifier having a predetermined fixed passband, of means for varying the effective band width of signals applied to said amplifier, a control circuit for said last-named means including an amplifier, an audio frequency amplifier, and means for simultaneously varying the gain of said audio frequency and control circuit amplifiers in response to variation in the signal amplitude above a predetermined value.
- a control circuit for said last-named means including an amplifier, an audio frequency amplifier, and means for simultaneously varying the gain of said amplifiers in the same sense with variations in frequency swing of a received signal, said last-named means including an audio frequency rectifier for deriving a gain control potential for said amplifiers.
- a control circuit for said last-named means including an amplifier, an audio frequency amplifier, and means for simultaneously varying the gain of said amplifiers in response to variation in the signal amplitude above a predetermined value.
- a variable frequency heterodyne oscillator responsive to the audio frequency output ofsaid system for varying the frequency of said oscillator in synchronism with frequency variations in a received signal
- said feedback means including an amplifier for feedback voltage, and means responsive to the audio frequency output of ⁇ said system for varying the audio frequency gain in said system and the amplifier gain in said feedback control means in predetermined relation.
- a relatively narrow band intermediate frequency amplifier circuit means for causing the effective band width of reception through said amplifier circuit to vary with percentage modulation variation above a predetermined value, an audio frequency amplifier circuit, and means for causing the signal lgain through said last-named circuit to vary conjointly with said band width variation, and in a sense to provide compensation in the signal output of said system for the effects of said bandV Width variation.
- a radio signal receiving system the combination of a first detector, a heterodyne oscillator coupled to said detector, an intermediate frequency amplifier coupled to said detector, an audio frequency signal channel coupled to said detector, means providing a feedback audio frequency control circuit between said audio frequency signal channel and said oscillator for varying the frequency of said oscillator in response to variations in the amplitude of audio frequency signals, and means for varying the gain through said audio frequency signal channel and the gain in said feedback circuit jointly and in the same sense in response to variations in the amplitude of audio frequency signals above a predetermined amplitude.
- a frequency modulation signal receiving system the combination of means for deriving audio vfrequency output signals therefrom as a measure of the frequency swing of a received signal, means providing a variable-gain feedback oscillator frequency-control amplifier coupled to said last-named means, a variable-gain 'audio frequency amplifier for'said system, means forY adjusting the amplitude of the audio frequency signals applied to said audio frequency amplifier and to said variable-gain amplifier, and means including an audio frequency rectifier responsive to the audio frequency output of said systemA said variable gain amplifier to cause the oscillator Y frequency to vary in synchronism with an incoming signal, a variable gain audio frequency amplifier for said system, means for adjusting the amplitude of the audio frequency signals applied to said audio frequency amplifier and to said variable gain amplifier, and means including an audio frequency rectifier responsive to the audio frequency output of said system for applying to said variable gain audio frequency amplifier andto said variable gain control amplifier a variable gain-controlling potential.
- a frequency modulation signal receiving system the combination of an intermediate frequency amplifier providing a predetermined signal passband, a heterodyne oscillator, frequency nel connected with said intermediate frequency amplifier and including an audio frequency amplifier circuit, means for deriving an audio frequency signal from said circuit, means providing a path including an amplifier for feeding back said derived audio frequency signal to said oscillator frequency control means to cause the oscillator frequency to vary from a normal value in synchronism with the frequency variation of a received signal, thereby to vary the effective l0 mined value.
Description
w. R. KocH 222,973
WIDE BAND FREQUENCY MODULATIN RECEIVING SYSTEM may a2, "1942.,
Filed June? 29, 1940 '3m emo: l #ming Patented May 12, 1942 usaran vsrarss PATENT vorgies `WIDE BAND FREQUENCY MODULATION RECEIVING SYSTEM Winfield R. Koch, Haddonfield, N. J., assgnor to Radio Corporation ofAmerica, a corporation of Delaware Application June 29, 1940, Serial No. 343,137
GCI. Z50-20) Claims.
This invention relates to wide band frequency modulation receiving systems, and has for .its
primary object to provide an improved receiving system, providing noise and interference reduction with wide band frequency modulation.
It is a further object of the present invention 4to provide a frequency modulation receiving-system having automatic band width control with wide band operation, and means therein for preventing audio frequency distortion.
It is a further object of the present invention to provide a frequency modulation receiving system having awide band signalinput circuit and tion to provide an improved wide band frequency modulation signal receiving system having means thereinrfor varying the effective band width of the intermediate frequency circuits, with variations in percentage modulation or frequency swing, and in accordance with variations in the audio frequency outputof the system'as a measure of the .frequency swing.
It isalso an object of the present invention to provide means in a frequency modulation signal receiving system for varying a heterodyne oscillator frequency to maintain a received signal within the intermediate frequency pass band with variations in modulation above a predetermined percentage or frequency swing, While permitting theV frequency swing or modulation to occupy at all times a major portion of the intermediate frequencypass band width.
For lowest background noise and minimum interference from othersignals in a frequency modulation receiving system, it is desirable to :provide a signal band width substantially equal to the pass band of the system. In accordance with the invention, for this purpose.' instead of varying the intermediate frequency band width, the effective band width of the signal is altered -by feedback voltage control through the heterodyne oscillator to cause the intermediate frequency signal to be maintained at all times at a band width covering a major portion of the pass band width of the intermediate frequency .circuitsfor example, eighty percent of the band width, and to cause the intermediate frequency swing or signal band width to be maintained Within the band `width limits ofthe Vintermediate ,frequency circuitsfor higher percentage modulation, without causing distortion of the audio `frequency output signal.
It is, therefore, anobject of the invention to provide `means 'whereby the audiov frequency amplification may be changed .automatically with variations in the modulation or signal frequency swing above .a predetermined value, preferably in the intermediate .frequency circuits, to secure the proper audio frequency output level and dy- -namic operating range -of the signal at the output circuit of the receiving system. IThis contenu` plates that both the effective band Width of reception and the audio frequency gain in the system may be'controlled automatically in response to variations in anaudio vfrequency control volt- `age vas `a measureof the percentage modulation or frequency swing, thereby Ytopermit ythe effective band width to vary without audio frequency distortion.
It is a still further lobject ofthe present invention to provide an improved frequency modulation receiving system having a Wide band sig- Vnal input circuit and a relatively narrow band intermediate frequency circuit Yand control means .for utilizing a major portion of the band width fof said last-named circuit for lo-w modulation signals thereby to reduce noise and, with feedback control of the oscillator frequency in sync'hronism with the incoming signal, to prevent the intermediate frequency swing from exceeding the band Width o-f the intermediate frequency circuit with full modulation.
While negative feedbackfcontrol of the oscillator frequency may be provided to narrow the signal band, it may be desirable with low modulation levels to utilize positive feedback to widenv the band of the signal to equal the pass band of the receiving system, in which'fcase the. audio frequency gain of the system should be correspondingly reduced to prevent distortion. 4
' The invention will better 4be understood, `however, from the following description, vwhen considered in connection vwith the accompanying drawing, and its scope is pointed out in the appended claims.
In the drawing, Figure 1 is a schematic circuit diagram of a signal receiving system-embodying the invention, and
Figure 2 is a graph showing curves illustrating certain operating characteristics of the circuit of Fig. 1.
Referring to Fig. 1, the wide band frequency modulation receiving system shown comprises a wide band tunable r. f. or high frequency amplifier 5 coupled to a suitable signal source such y In the receiving system described, the amplifier stages I3 is a gain control amplifier stage which is preferably of the pentagrid type, having a signal input grid I6 coupled through a potentiometer I'I, and an impedance coupling network I8, to the output circuit I9 of the preceding amplier stage I2. A gain control grid is also provided in the tube I3 as part of a volume control or expander means to control amplitude of signals transmitted through the stage. Variable gain controlling potential for the grid 2U is derived througha control circuit 2| from the output impedance 22` of a rectifier 23, a suitable filter network 24 being included in the connection between the circuit 2| and the output impedance.
The rectifier 23 and the associated circuits include a suitable source of fixed biasing potential 25 for the control grid 20 and a delay bias potential source 26 for the rectifier 23 effective to prevent response of the rectifier to signals below a certain value of applied signal potential corresponding to a certain percentage modulation or swing. The percentage modulation or frequency swing is determined by the audio frequency o'utput of' the receiving system a portion of which is applied to the rectifier 23 from the first stage audio frequency amplifier output circuit I9 through a supply lead21, a coupling capacitor 28 and an input potentiometer device 29.
Audio frequency signals are also derived from the output circuit I9 through the potentiometer device I'I and a variable tap connection 3D thereon for a feedback control or variable gain amplifier stage 3|, also of the pentagrid type having a control grid 32 connected with the tap 30 as shown, and having a gain control grid 33 connected with the bias supply lead 2| from the rectifier 23.
The output circuit 34 of the amplifier stage 3| is coupled through a suitable coupling capacitor 35 and a circuit 36 with frequency control means 31 connected with the oscillator 8 in proper phase relation to cause the oscillator frequency to Vary in synchronism with the incoming signal, above and below a normal frequency by an amount dependent upon the adjustment of the applied signal from the tap 30 and the bias control potential on the gain control grid 33 of the control amplifier 3|. v
The audio frequency output from the discrim- Vinator network I Il .through the second detector I I and amplifier I 2 to the tap 39 provides a measure of the percentage modulation or frequency swing of a received signal. This causes the feedback control amplier 3| to have a negative feedback action on the oscillator frequency lwhich then swings with the signal and in synchronism therewith, thereby to cause the effective band width of reception through the narrow band intermediate frequency amplifier 9 to vary with the percentage modulation.
Thus, if the signal at a mean intermediate frequency of 5 mc. is one hundred percent modulated to swing i kc., the oscillator may at the same time be caused to swing in frequency 1-75 kc., making a differential swing of 25 kc. in the i. f. amplifier signal for one hundred percent modulation. This tends to result in a reduction in theaudio frequency output which is compensated as will hereinafter be pointed out.
With this arrangement, the intermediate frequency amplifier may provide a relatively high gain and a relatively narrow frequency response, while the input circuit or r. f. amplifier may have a desired wide band characteristic. Then, assuming further a 40 mc. signal-modulated i100 kc. at one hundred percent modulation, and i2() kc. for a relatively low modulation of twenty percent, the intermediate frequency amplifier may be made substantially only 50 kc. wide.
In accordance with the invention, the effective band width of the signal is altered by feedback control through the heterodyne oscillator to provide an i. f. signal which occupies substantially eighty percent of the i. f. band. width with twenty percent modulation, for example, as indicated in connection with the output response curve 40 of the discriminator network and detector,`while the remaining veighty percent change in percentage modulation causes a relatively slight increase in the effective use of the full band width of the amplifier 9.
In other words, signals of relatively low percentage modulation are caused to occupy a major portion of the band width of the signal channel, preferably in a narrow band high gain i. f. circuit and negative feedback voltage control to the oscillator is provided and controlled to a degree to preventthe signal swing from exceeding the limits of the pass band of the i. f. amplifier up to substantially full modulation.
In Fig. 2, the curve 4| indicates the amplitude of the input andoutput signal of the gain control ampliiier stage I3 with relatively low frequency swing, such as, below twenty percent modulation, while the curve 42 indicates the vinput voltage with one hundred percent modulation and the resulting output signal voltage is indicated by the curve 43. This additional outputis provided by the control rectifier 23 which causes an increasing positive bias on both grids 33 and 20 vand volume range expansion above 20 percent modulation in the present example.
This action prevents distortion of the audio frequency output which would otherwise result from altering the effective modulation of the intermediate frequency signal by variation of the oscillator frequency and includes controlling the effective band width of reception through the i. f. amplier, with variations in swing of the signal and the gain of the audio frequency amplifier and feedback control path simultaneously, so that the output of the receiver faithfully follows the modulation changes above the predetermined low modulation level without exceeding the band width of' the amplifier. At one hundred percent modulation, substantially the entire band is used and the audio frequency gainis maximum.
The rectifier 23. and its associated circuits have `a time constant which provides for a rapid response and slow recovery characteristic thereby insuring that the system will respond to but will Vnot follow the modulation frequency changes.
From the foregoing descriptiomit will be seen that both the amount of feedback and the audio frequency gain may automatically be controlled i from a rectifier operated by the audio voltages derived from the frequency modulation receiving system following the discriminator network, as a measure of the percentage modulation, thereby simultaneously making the effective band width of reception vary with the percentage modulation above a predetermined low percentage and compensating for'the effective reduction in the audio frequency signal amplitude from the detector by increasing the gain in both .the audio frequency and feedback control channels.
I claim as my invention:
1. In a radio signal receiving system, the combination with a signal amplifier having a predetermined fixed passband, of means for varying the effective band width of signals applied to said amplifier, a control circuit for said last-named means including an amplifier, an audio frequency amplifier, and means for simultaneously varying the gain of said audio frequency and control circuit amplifiers in response to variation in the signal amplitude above a predetermined value.
2. In a frequency modulation signal receiving system, the combination with an intermediate frequency amplifier having a predetermined frequency passband, of means for varying the effective band width of signals applied to said amplifier, a control circuit for said last-named means including an amplifier, an audio frequency amplifier, and means for simultaneously varying the gain of said amplifiers in the same sense with variations in frequency swing of a received signal, said last-named means including an audio frequency rectifier for deriving a gain control potential for said amplifiers.
3. In a frequency modulation signal receiving system, the combination with an intermediate frequency amplifier having a predetermined frequency passband, of means for varying the effective band width of signals applied to said amplier, a control circuit for said last-named means including an amplifier, an audio frequency amplifier, and means for simultaneously varying the gain of said amplifiers in response to variation in the signal amplitude above a predetermined value.
4. In a frequency modulation signal receiving system, the combination of a variable frequency heterodyne oscillator, feedback control means responsive to the audio frequency output ofsaid system for varying the frequency of said oscillator in synchronism with frequency variations in a received signal, said feedback means including an amplifier for feedback voltage, and means responsive to the audio frequency output of `said system for varying the audio frequency gain in said system and the amplifier gain in said feedback control means in predetermined relation.
5. In a frequency modulation signal receiving system, the combination of a relatively narrow band intermediate frequency amplier having a predetermined passband, a variable frequency heterodyne oscillator, feedback control means responsive to the audio frequency output of said system for varying the frequency of said oscillator in synchronism with frequency variations in a received signal, to limit the signal frequency band to the passband of said amplifier, said feedback means including an amplifier for feedback voltage-and means responsive tothe audio frequency output `of saidsystem forvarying the audio lfrequency gain -in said system and the of the audio frequency output of said system is enhanced.
6. In a frequency modulation receiving sys tem, the combination of a relatively narrow band intermediate frequency amplifier circuit, means for causing the effective band width of reception through said amplifier circuit to vary with percentage modulation variation above a predetermined value, an audio frequency amplifier circuit, and means for causing the signal lgain through said last-named circuit to vary conjointly with said band width variation, and in a sense to provide compensation in the signal output of said system for the effects of said bandV Width variation. i
7. In a radio signal receiving system, the combination of a first detector, a heterodyne oscillator coupled to said detector, an intermediate frequency amplifier coupled to said detector, an audio frequency signal channel coupled to said detector, means providing a feedback audio frequency control circuit between said audio frequency signal channel and said oscillator for varying the frequency of said oscillator in response to variations in the amplitude of audio frequency signals, and means for varying the gain through said audio frequency signal channel and the gain in said feedback circuit jointly and in the same sense in response to variations in the amplitude of audio frequency signals above a predetermined amplitude.
8. In a frequency modulation signal receiving system, the combination of means for deriving audio vfrequency output signals therefrom as a measure of the frequency swing of a received signal, means providing a variable-gain feedback oscillator frequency-control amplifier coupled to said last-named means, a variable-gain 'audio frequency amplifier for'said system, means forY adjusting the amplitude of the audio frequency signals applied to said audio frequency amplifier and to said variable-gain amplifier, and means including an audio frequency rectifier responsive to the audio frequency output of said systemA said variable gain amplifier to cause the oscillator Y frequency to vary in synchronism with an incoming signal, a variable gain audio frequency amplifier for said system, means for adjusting the amplitude of the audio frequency signals applied to said audio frequency amplifier and to said variable gain amplifier, and means including an audio frequency rectifier responsive to the audio frequency output of said system for applying to said variable gain audio frequency amplifier andto said variable gain control amplifier a variable gain-controlling potential.
10. In a frequency modulation signal receiving system, the combination of an intermediate frequency amplifier providing a predetermined signal passband, a heterodyne oscillator, frequency nel connected with said intermediate frequency amplifier and including an audio frequency amplifier circuit, means for deriving an audio frequency signal from said circuit, means providing a path including an amplifier for feeding back said derived audio frequency signal to said oscillator frequency control means to cause the oscillator frequency to vary from a normal value in synchronism with the frequency variation of a received signal, thereby to vary the effective l0 mined value.
7 control means for said'oscillator, a signal chanba'nd Width of the vsignal through said intermediate frequency amplier, and means for varying the gain in said feedback path and in said audio frequency amplifier circuit jointly with variation in the amplitude of audio frequency signals therein as a measure of said frequency variation of a received signal, and means for preventing operation of said last-named means for signal frequency variations below a predeter- WINFIELD R. KOCH.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL58898D NL58898C (en) | 1940-06-29 | ||
| US343137A US2282973A (en) | 1940-06-29 | 1940-06-29 | Wide band frequency modulation receiving system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US343137A US2282973A (en) | 1940-06-29 | 1940-06-29 | Wide band frequency modulation receiving system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2282973A true US2282973A (en) | 1942-05-12 |
Family
ID=23344855
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US343137A Expired - Lifetime US2282973A (en) | 1940-06-29 | 1940-06-29 | Wide band frequency modulation receiving system |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US2282973A (en) |
| NL (1) | NL58898C (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2476964A (en) * | 1942-07-17 | 1949-07-26 | Int Standard Electric Corp | Receiving system for frequency or pulse modulated electromagnetic waves |
| US2514443A (en) * | 1943-06-07 | 1950-07-11 | Rca Corp | Selectivity control system |
| US2560312A (en) * | 1947-10-03 | 1951-07-10 | Philco Corp | Tuning aid for radio receivers |
| US3048661A (en) * | 1958-12-11 | 1962-08-07 | Itt | Multiplex communication receiver |
| US3238460A (en) * | 1961-04-25 | 1966-03-01 | Bell Telephone Labor Inc | Frequency modulation receiver with frequency restricted feedback |
-
0
- NL NL58898D patent/NL58898C/xx active
-
1940
- 1940-06-29 US US343137A patent/US2282973A/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2476964A (en) * | 1942-07-17 | 1949-07-26 | Int Standard Electric Corp | Receiving system for frequency or pulse modulated electromagnetic waves |
| US2514443A (en) * | 1943-06-07 | 1950-07-11 | Rca Corp | Selectivity control system |
| US2560312A (en) * | 1947-10-03 | 1951-07-10 | Philco Corp | Tuning aid for radio receivers |
| US3048661A (en) * | 1958-12-11 | 1962-08-07 | Itt | Multiplex communication receiver |
| US3238460A (en) * | 1961-04-25 | 1966-03-01 | Bell Telephone Labor Inc | Frequency modulation receiver with frequency restricted feedback |
Also Published As
| Publication number | Publication date |
|---|---|
| NL58898C (en) |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2298930A (en) | Phase distortion correction | |
| US2056607A (en) | Sound and television receiver | |
| US2802939A (en) | Squelch system | |
| US3002090A (en) | Automatic-gain-control system | |
| US2527617A (en) | Radio receiving system | |
| US2282973A (en) | Wide band frequency modulation receiving system | |
| US2233317A (en) | Amplifier for television system | |
| US2264019A (en) | Signal-translating system | |
| US2288434A (en) | Automatic gain control system | |
| US2923887A (en) | Electronic circuit arrangement for the controlled amplification of a desired signal | |
| US2250862A (en) | Combination amplitude-modulationfrequency-modulation receiver | |
| US2245685A (en) | Automatic frequency control system | |
| US2194292A (en) | Carrier-frequency receiving system | |
| US2948808A (en) | Single sideband communication system | |
| US2420249A (en) | Amplitude modulation reducing circuit | |
| US2058411A (en) | Radio receiver | |
| US2078762A (en) | Automatic tone control system | |
| US2573248A (en) | Television receiver | |
| US2177713A (en) | Frequency-selective network | |
| US2379720A (en) | Receiver fidelity control system | |
| US2172160A (en) | Delayed automatic volume control | |
| US2013121A (en) | Automatic amplification control | |
| US2959673A (en) | Radio receiver squelch control | |
| US3241066A (en) | Compandor system having an analog signal controlled compressor and an auxiliary signal controlled expander | |
| US2216582A (en) | Automatic volume control with noise suppression |