GB546677A - Improvements in or relating to systems for maintaining a constant mean frequency in transmissions by frequency modulated carrier wave - Google Patents
Improvements in or relating to systems for maintaining a constant mean frequency in transmissions by frequency modulated carrier waveInfo
- Publication number
- GB546677A GB546677A GB3689/41A GB368941A GB546677A GB 546677 A GB546677 A GB 546677A GB 3689/41 A GB3689/41 A GB 3689/41A GB 368941 A GB368941 A GB 368941A GB 546677 A GB546677 A GB 546677A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- modulation
- oscillator
- phase
- carrier wave
- 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
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/02—Details
- H03C3/09—Modifications of modulator for regulating the mean frequency
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/02—Details
- H03C3/04—Means in or combined with modulating stage for reducing amplitude modulation
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/10—Angle modulation by means of variable impedance
- H03C3/28—Angle modulation by means of variable impedance using variable impedance driven mechanically or acoustically
Abstract
546,677. Automatic control systems ; frequency modulation. ELECTRICAL RESEARCH PRODUCTS, Inc. March 18, 1941, No. 3689. Convention date, March 30, 1940. [Class 38 (iv)] [Also in Group XL] Oscillation frequency.-The mean frequency of a frequency modulated carrier wave oscillator is corrected for drift by deriving from the modulated wave by frequency division a subharmonic oscillation having diminished frequency modulation and a mean frequency such that the side bands of higher order than the first representing the diminished modulation are suppressed and controlling the carrier oscillator by beat currents between this harmonic and oscillations of a fixed frequency. The carrier oscillator comprises two vacuum tubes 23, 24 in push-pull, a tuned circuit comprising inductance 25 and fixed and variable condensers 27, 29 and feed-back condensers 30, 31. Amplitude modulation is prevented by a choke coil 36 in series with a bias resistance 32. Frequency modulation by a signal source 40 is produced by control tubes 37, 38 in push-pull across the tuning inductance 25 a loose coupled coil 85 and phase-shifting network 47 producing at the input terminals of the control tubes a radio-frequency voltage exactly in quadrature with the voltage across the inductance 25. The coil 85 also furnishes current to the output leads 48, 49 from which a cascade connection of frequency dividers 52, 58 ... 59, 60 feeds two balanced modulators through transformers 61, 62. A master frequency oscillator 67 provides potentials to the grids of the modulator valves 63 ... 66 through two phase-splitting networks 69, 70 so that two beat currents in quadrature arise from any change in the mean frequency and the modulated carrier wave. A two phase motor 78 actuates the condensers 29 in such case to alter the tuning of the oscillator 23, 24 and correct the change. In a frequency modulated transmitter operating at about 40 megacycles the oscillator frequency has a normal value of 5120 cycles. The maximum frequency swing due to modulation is taken as 100 kilocycles above and below the radiated carrier frequency or a deviation of 12.5 kilocycles in the oscillator frequency. To reach a modulation of the subharmonic having an amplitude less than the lowest significant fre-. quency of speech signals the frequency is divided to the 1024th part by 10 dividers in tandem each reducing by one half. The phase libration representing the modulation amounts then to only 12 degrees and the resulting rapid oscillation of the motor 78 with zero beat frequency is suppressed by the inertia and friction of the mechanical parts which may include a worm drive with or without eddy current damping, a torsionally flexible shaft or spring coupling. The frequency divided shown is of the type described in U.S.A. Specification 2,159,595 and comprises a vacuum tube 57, a bridge network 50 of copper oxide rectifiers, a tuned output circuit and a feed back to the terminals of the rectifiers through a pair of bridging inductances.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US319877A US2218524A (en) | 1940-02-20 | 1940-02-20 | Frequency modulation system |
US326898A US2250104A (en) | 1940-02-20 | 1940-03-30 | Frequency regulation |
Publications (1)
Publication Number | Publication Date |
---|---|
GB546677A true GB546677A (en) | 1942-07-24 |
Family
ID=26982185
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB3689/41A Expired GB546677A (en) | 1940-02-20 | 1941-03-18 | Improvements in or relating to systems for maintaining a constant mean frequency in transmissions by frequency modulated carrier wave |
Country Status (6)
Country | Link |
---|---|
US (2) | US2218524A (en) |
BE (1) | BE441132A (en) |
DE (1) | DE882424C (en) |
FR (2) | FR869048A (en) |
GB (1) | GB546677A (en) |
NL (1) | NL67475C (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2434259A (en) * | 1943-06-22 | 1948-01-13 | Bell Telephone Labor Inc | Circuit arrangement utilizing a plurality of electron discharge devices |
Families Citing this family (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2425657A (en) * | 1941-04-17 | 1947-08-12 | Rca Corp | Short-wave apparatus |
US2440600A (en) * | 1941-05-14 | 1948-04-27 | Rca Corp | Electric motor control |
US2475779A (en) * | 1941-05-14 | 1949-07-12 | Rca Corp | Wave length modulator and control means |
US2966676A (en) * | 1942-06-30 | 1960-12-27 | Bessie E Fox | Electronic apparatus and method for measuring distance |
US2794956A (en) * | 1942-06-30 | 1957-06-04 | Fox Benjamin | Frequency modulation system |
US2422422A (en) * | 1942-08-31 | 1947-06-17 | Rca Corp | Reactance tube controlled generator |
US2415868A (en) * | 1942-10-28 | 1947-02-18 | Rca Corp | Timing modulation |
US2511137A (en) * | 1944-12-16 | 1950-06-13 | Rca Corp | Frequency control |
US2609509A (en) * | 1945-06-13 | 1952-09-02 | Bertram C Hill | Electrical testing apparatus |
US2490448A (en) * | 1945-11-09 | 1949-12-06 | Amalgamated Wireless Australas | Frequency changer |
US2588730A (en) * | 1947-05-02 | 1952-03-11 | Wayne R Johnson | Method and apparatus for frequency response measurement |
US2615129A (en) * | 1947-05-16 | 1952-10-21 | Edwin M Mcmillan | Synchro-cyclotron |
US2659813A (en) * | 1950-02-11 | 1953-11-17 | Bell Telephone Labor Inc | Frequency modulation repeater |
US2688730A (en) * | 1950-10-18 | 1954-09-07 | Smith Meeker Engineering Co | Stable frequency generator system |
US2761065A (en) * | 1953-05-27 | 1956-08-28 | Harris A Robinson | Frequency control system |
US3202918A (en) * | 1962-10-03 | 1965-08-24 | Armand P Lucchesi | Frequency multiplier |
US3789302A (en) * | 1972-03-31 | 1974-01-29 | Microwave Ass Inc | Fm heterodyne transmitter |
US10424278B2 (en) * | 2017-08-02 | 2019-09-24 | Applied Invention, Llc | Bell with subharmonic difference tone |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE399079A (en) * | 1931-09-17 | |||
NL57985C (en) * | 1937-07-09 |
-
1940
- 1940-02-20 US US319877A patent/US2218524A/en not_active Expired - Lifetime
- 1940-03-30 US US326898A patent/US2250104A/en not_active Expired - Lifetime
-
1941
- 1941-01-02 FR FR869048D patent/FR869048A/en not_active Expired
- 1941-01-24 FR FR878762D patent/FR878762A/en not_active Expired
- 1941-03-18 GB GB3689/41A patent/GB546677A/en not_active Expired
- 1941-03-27 DE DEW719D patent/DE882424C/en not_active Expired
- 1941-04-10 BE BE441132D patent/BE441132A/xx unknown
-
1944
- 1944-02-11 NL NL115248A patent/NL67475C/xx active
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2434259A (en) * | 1943-06-22 | 1948-01-13 | Bell Telephone Labor Inc | Circuit arrangement utilizing a plurality of electron discharge devices |
Also Published As
Publication number | Publication date |
---|---|
FR869048A (en) | 1942-01-22 |
BE441132A (en) | 1941-10-31 |
US2250104A (en) | 1941-07-22 |
NL67475C (en) | 1951-03-15 |
US2218524A (en) | 1940-10-22 |
FR878762A (en) | 1943-01-29 |
DE882424C (en) | 1953-07-09 |
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