GB629861A - Improvements in electric wave transmission systems - Google Patents
Improvements in electric wave transmission systemsInfo
- Publication number
- GB629861A GB629861A GB33670/47A GB3367047A GB629861A GB 629861 A GB629861 A GB 629861A GB 33670/47 A GB33670/47 A GB 33670/47A GB 3367047 A GB3367047 A GB 3367047A GB 629861 A GB629861 A GB 629861A
- Authority
- GB
- United Kingdom
- Prior art keywords
- band
- carrier
- stages
- frequency
- filter
- 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
- H03C1/00—Amplitude modulation
- H03C1/52—Modulators in which carrier or one sideband is wholly or partially suppressed
- H03C1/60—Modulators in which carrier or one sideband is wholly or partially suppressed with one sideband wholly or partially suppressed
Landscapes
- Amplitude Modulation (AREA)
Abstract
629,861. Modulating systems. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 19, 1947, No. 33670. Convention date, Oct. 15, 1943. [Class 40 (v)] A wide-band signal, e.g. an audio broadcasting signal, is converted into a carrier wave with single side-band by first producing a carrier with two side-bands and then eliminating one of the bands by successive stages. Fig. 1 shows the arrangement of the stages, and Fig. 2 the frequency spectra at the successive stages. The signal band I of Fig. 2 is applied through a filter 2 to a balanced modulator fed with a carrier from source 4, giving a weak carrier and two side-bands II. These are passed to a second balanced modulator 5 fed from source 6 with a carrier of frequency 4 kc/s. higher than the source 4. From the resulting frequencies, the spectrum III is selected and is reduced in band-width by a filter 7 so as to include one complete sideband, a 4 kc/s. carrier, and a section of the other side-band, as shown at IV. This spectrum is then subjected to a double change of frequency at 8 which brings the carrier down from 4 kc/s. to 450 cycles, as indicated at V, and is applied to a band-pass filter 9 which rejects the residual lower side-band and passes the carrier and upper side-band VI. This single side-band is now raised in frequency by modulating it at 10 in two stages on carriers which differ by 4.5 kc/s. (see curve VII), and is passed through a filter 11 which passes the new carrier of 4950 cycles and the upper side-band VIII. Further frequencychanging stages 12 precede the radio transmitter 13.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR629861X | 1943-10-15 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB629861A true GB629861A (en) | 1949-09-29 |
Family
ID=8990673
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB33670/47A Expired GB629861A (en) | 1943-10-15 | 1947-12-19 | Improvements in electric wave transmission systems |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB629861A (en) |
-
1947
- 1947-12-19 GB GB33670/47A patent/GB629861A/en not_active Expired
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