GB774113A - Improvements in or relating to automatic gain control circuits for television receivers - Google Patents

Improvements in or relating to automatic gain control circuits for television receivers

Info

Publication number
GB774113A
GB774113A GB2961753A GB2961753A GB774113A GB 774113 A GB774113 A GB 774113A GB 2961753 A GB2961753 A GB 2961753A GB 2961753 A GB2961753 A GB 2961753A GB 774113 A GB774113 A GB 774113A
Authority
GB
United Kingdom
Prior art keywords
resistor
rectifier
synch
grid
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
Application number
GB2961753A
Inventor
James John Billin
Ronald Charles Hall
Ivan Godier
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.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
Electrical and Musical Industries 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
Priority to NL191748D priority Critical patent/NL191748A/xx
Application filed by EMI Ltd, Electrical and Musical Industries Ltd filed Critical EMI Ltd
Priority to GB2961753A priority patent/GB774113A/en
Priority to US464545A priority patent/US2885472A/en
Priority to DEE9744A priority patent/DE1010561B/en
Priority to FR1110969D priority patent/FR1110969A/en
Publication of GB774113A publication Critical patent/GB774113A/en
Priority to GB19933/57A priority patent/GB890743A/en
Priority to US743705A priority patent/US2942063A/en
Priority to FR768784A priority patent/FR73778E/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
    • H04N5/52—Automatic gain control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/08—Separation of synchronising signals from picture signals
    • 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)
  • Ultra Sonic Daignosis Equipment (AREA)

Abstract

774,113. Automatic gain control. ELECTRIC & MUSICAL INDUSTRIES, Ltd. Oct. 15, 1954 [Oct. 27, 1953], No .29617/53. Class 40(5) In a television receiver an A.G.C. voltage is derived by adding inverted synch. pulses to the complete video signal, so that the minimum amplitude in the combined signals corresponds to minimum vision modulation. The complete video signal, in which synch. pulses are 'positive going, is fed from video amplifier 1 to the grid of a grid-current biased synch. separator 5, via a series resistor 4. The complete video signal is also fed to a rectifier 13 via resistor 14, which may alternatively be connected to point B. Inverted synch. pulses of amplitude equal to or greater than that of the pulses in the complete video signal are also fed, to the rectifier 13, via resistor 12, from the anode of the synch. separator 5. The minimum amplitude at the anode of the rectifier 13 then corresponds to black level '(Figs. 5, 6 not shown). The cathode of rectifier 13 is returned to a suitable negative sourceas shown, the grid circuit of a line scanning amplifier 16-via resistor 16, and the A.G.C. voltage is obtained across smoothing condenser 17. A contrast control may be obtained by connecting the anode of rectifier 13 to a variable positive bias source 18. Alternatively, a variable resistor may be used in the cathode circuit of the synch. separator 5, Fig. 7 (not shown). In this case the grid leak 20 and screen potentiometer resistor 9 are returned directly to the cathode: the grid leak 20 may alternatively be returned to the screen grid. In another embodiment, Fig. 8 (not shown) the resistor 14 is connected to the anode of the amplifier 1 via a blocking condenser, a separate diode D.C. resistor being used to set the D.C. level in the signal applied to the rectifier 13. In this arrangement contrast control is obtained bv variation of the cathode bias of the D.C. restorer. Specification 484,202 [Group XL] is referred to.
GB2961753A 1953-10-27 1953-10-27 Improvements in or relating to automatic gain control circuits for television receivers Expired GB774113A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
NL191748D NL191748A (en) 1953-10-27
GB2961753A GB774113A (en) 1953-10-27 1953-10-27 Improvements in or relating to automatic gain control circuits for television receivers
US464545A US2885472A (en) 1953-10-27 1954-10-25 Automatic gain control circuits for television receivers
DEE9744A DE1010561B (en) 1953-10-27 1954-10-25 Circuit arrangement for deriving a control voltage in television receivers
FR1110969D FR1110969A (en) 1953-10-27 1954-10-27 Improvements to automatic amplification control circuits for television receivers
GB19933/57A GB890743A (en) 1953-10-27 1957-06-25 Improvements in or relating to automatic gain control circuits for television receivers
US743705A US2942063A (en) 1953-10-27 1958-06-23 Automatic gain control circuits for television receivers
FR768784A FR73778E (en) 1953-10-27 1958-06-25 Improvements to automatic amplification control circuits for television receivers

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2961753A GB774113A (en) 1953-10-27 1953-10-27 Improvements in or relating to automatic gain control circuits for television receivers

Publications (1)

Publication Number Publication Date
GB774113A true GB774113A (en) 1957-05-08

Family

ID=10294403

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2961753A Expired GB774113A (en) 1953-10-27 1953-10-27 Improvements in or relating to automatic gain control circuits for television receivers

Country Status (1)

Country Link
GB (1) GB774113A (en)

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