GB742942A - Automatic gain control in television apparatus - Google Patents
Automatic gain control in television apparatusInfo
- Publication number
- GB742942A GB742942A GB569653A GB569653A GB742942A GB 742942 A GB742942 A GB 742942A GB 569653 A GB569653 A GB 569653A GB 569653 A GB569653 A GB 569653A GB 742942 A GB742942 A GB 742942A
- Authority
- GB
- United Kingdom
- Prior art keywords
- valve
- anode
- grid
- signals
- pulses
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Television Receiver Circuits (AREA)
- Picture Signal Circuits (AREA)
Abstract
742,942. Automatic gain control. MURPHY RADIO, Ltd. Feb. 26, 1954 [Feb. 28, 1953], No. 5696/53. Class 40 (5). In a television A.G.C. circuit for positivelymodulated signals, video signals in which the sync. signals comprise peak positive are applied from a video stage to the grid of a cathode follower 3. A.C. coupling is employed, the valve 3 acting as a D.C. restorer by virtue of grid current and being arranged to be cut off for signals more negative than the black level. The adjustment may be made by means of an anode resistance 17. D.C. coupling to this valve may alternatively be used. The cathode follower 3 is cathode coupled to an amplifier 4 comprising a triode-connected pentode, the anode of which is fed with gating impulses, derived from the line or frame generators via a transformer 9. A delay network 8 is interposed so that the valve is only capable of conduction during the # back porch " period following the sync. pulses. A smoothed A.G.C. voltage is obtained across resistance 14. The signal level at which conduction occurs in the valve 4 is determined by the grid potential, derived from a variable potentiometer 12 which is utilized as contrast control. In an alternative arrangement, Fig. 2 (not shown), the gating pulses are applied to the grid, instead of the anode of the valve 4 via a potentiometer comprising the contrast control. In this case the anode is connected via a load resistor to the H.T. line and the negativegoing pulses which appear in the anode circuit are applied via a blocking condenser to a diode rectifier, the smoothed output of which constitutes the A.G.C. voltage.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB569653A GB742942A (en) | 1953-02-28 | 1953-02-28 | Automatic gain control in television apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB569653A GB742942A (en) | 1953-02-28 | 1953-02-28 | Automatic gain control in television apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
GB742942A true GB742942A (en) | 1956-01-04 |
Family
ID=9800924
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB569653A Expired GB742942A (en) | 1953-02-28 | 1953-02-28 | Automatic gain control in television apparatus |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB742942A (en) |
-
1953
- 1953-02-28 GB GB569653A patent/GB742942A/en not_active Expired
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