GB787649A - Improvements in or relating to interference limiters - Google Patents

Improvements in or relating to interference limiters

Info

Publication number
GB787649A
GB787649A GB3646854A GB3646854A GB787649A GB 787649 A GB787649 A GB 787649A GB 3646854 A GB3646854 A GB 3646854A GB 3646854 A GB3646854 A GB 3646854A GB 787649 A GB787649 A GB 787649A
Authority
GB
United Kingdom
Prior art keywords
grid
contrast
interference
potential
video amplifier
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
Application number
GB3646854A
Inventor
Donald Henry Fisher
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pye Electronic Products Ltd
Original Assignee
Pye Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Pye Ltd filed Critical Pye Ltd
Priority to GB3646854A priority Critical patent/GB787649A/en
Priority to FR1138958D priority patent/FR1138958A/en
Publication of GB787649A publication Critical patent/GB787649A/en
Expired legal-status Critical Current

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
    • H04N5/57—Control of contrast or brightness

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Television Receiver Circuits (AREA)

Abstract

787,649. Automatic gain control. PYE, Ltd. Dec. 16, 1955 [Dec. 16, 1954], No. 36468/54. Class 40 (5). In a television receiver in which interference is limited by employing a discharge tube as a video amplifier so that the interference would occur beyond the knee of the anode voltage/grid voltage curve, the contrast is altered by varying the D.C. potential of an electrode and the output is fed to an A.G.C. circuit which compensates for the change in clipping level caused by variations of the contrast control. In a positive modulation system the input to video amplifier V1 is such that the interference pulses are lost below the lower knee of the anode voltage/grid voltage curve (Fig. 2, not shown), and the output is fed through cathode follower V2 to gating tube V3 to which pulses are applied to the grid to generate an A.G.C. voltage at the anode. Contrast is varied by adjusting the tapping on potentiometer P1 to vary the anode voltage of video amplifier V1. With the grid of discharge tube V3 returned to a fixed potential on potentiometer P2 variations in contrast would result in the black level remaining constant with variations in the peak white level. In order to overcome this, the grid potential of tube V3 is varied with the contrast control by making a connection over a resistor to the tap on potentiometer P1. In a similar manner the grid of cathode-ray tube T is also varied in potential by a connection over a resistor to this tap. In a modification, Fig. 3, suitable for use with negative modulation, the setting of resistor P4 determines the contrast. The output from the video amplifier V5 is fed through cathode follower V6 to an A.G.C. system comprising a sampling diode V7, an amplifier V8 and a smoothing rectifier D3.
GB3646854A 1954-12-16 1954-12-16 Improvements in or relating to interference limiters Expired GB787649A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB3646854A GB787649A (en) 1954-12-16 1954-12-16 Improvements in or relating to interference limiters
FR1138958D FR1138958A (en) 1954-12-16 1955-12-14 Interference limiter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3646854A GB787649A (en) 1954-12-16 1954-12-16 Improvements in or relating to interference limiters

Publications (1)

Publication Number Publication Date
GB787649A true GB787649A (en) 1957-12-11

Family

ID=10388428

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3646854A Expired GB787649A (en) 1954-12-16 1954-12-16 Improvements in or relating to interference limiters

Country Status (2)

Country Link
FR (1) FR1138958A (en)
GB (1) GB787649A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1074633B (en) * 1960-02-04 Blaupunkt-Werke GmbH HiIdesheim Television receiver with a device for keyed control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1074633B (en) * 1960-02-04 Blaupunkt-Werke GmbH HiIdesheim Television receiver with a device for keyed control

Also Published As

Publication number Publication date
FR1138958A (en) 1957-06-24

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