GB797114A - Improvements in or relating to automatic gain control systems for television receivers - Google Patents
Improvements in or relating to automatic gain control systems for television receiversInfo
- Publication number
- GB797114A GB797114A GB4412/56A GB441256A GB797114A GB 797114 A GB797114 A GB 797114A GB 4412/56 A GB4412/56 A GB 4412/56A GB 441256 A GB441256 A GB 441256A GB 797114 A GB797114 A GB 797114A
- Authority
- GB
- United Kingdom
- Prior art keywords
- synch
- anode
- pulses
- diode
- valve
- 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
- 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
- H04N5/52—Automatic gain control
- H04N5/53—Keyed automatic gain control
-
- 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
- H04N5/52—Automatic gain control
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Control Of Amplification And Gain Control (AREA)
- Television Receiver Circuits (AREA)
Abstract
797,114. Automatic gain control. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Feb. 13, 1956 [Feb. 21, 1955], No. 4412/56. Class 40 (5). In a television A.G.C. circuit for positivelymodulated signals, the complete video signal is derived, in such sense that the synch. pulses are positive-going, from the anode of an amplifier 1 and is applied via a blocking condenser to the anode of a diode 3. The complete signal is also fed to a synch. separator valve 2a in whose anode circuit negative-going synch. pulses appear; these are inverted and amplified by valve 2b and fed as positive-going pulses to the cathode of the diode 3. The diode 3 is as a consequence, rendered non-conductive during the synch. pulse periods and so acts as a black level clamp, the black level in the waveform applied to its anode being held approximately at the negative potential which is applied to terminals 4. This potential may be made variable and used as contrast control, and is such that valve 6 is only rendered conductive by the synch. pulses in the signal at the anode of diode 3. Pulses proportional to the height of the synch. pulses appear in the anode circuit of the valve 6 and are rectified by an A.C.-coupled diode 7, the resulting negative voltage across the load resistor 8 constituting the A.G.C. voltage. Reference has been directed by the Comptroller to Specification 774,578.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR1123004T | 1955-02-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB797114A true GB797114A (en) | 1958-06-25 |
Family
ID=9632931
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB4412/56A Expired GB797114A (en) | 1955-02-21 | 1956-02-13 | Improvements in or relating to automatic gain control systems for television receivers |
Country Status (2)
| Country | Link |
|---|---|
| FR (1) | FR1123004A (en) |
| GB (1) | GB797114A (en) |
-
1955
- 1955-02-21 FR FR1123004D patent/FR1123004A/en not_active Expired
-
1956
- 1956-02-13 GB GB4412/56A patent/GB797114A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR1123004A (en) | 1956-09-17 |
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