GB1493264A - Automatic gain control circuit - Google Patents

Automatic gain control circuit

Info

Publication number
GB1493264A
GB1493264A GB5098674A GB5098674A GB1493264A GB 1493264 A GB1493264 A GB 1493264A GB 5098674 A GB5098674 A GB 5098674A GB 5098674 A GB5098674 A GB 5098674A GB 1493264 A GB1493264 A GB 1493264A
Authority
GB
United Kingdom
Prior art keywords
sync
transistor
pedestal
video signal
separator
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
GB5098674A
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.)
Hitachi Ltd
Original Assignee
Hitachi 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 Hitachi Ltd filed Critical Hitachi Ltd
Publication of GB1493264A publication Critical patent/GB1493264A/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
    • H04N5/53—Keyed automatic gain control

Abstract

1493264 Television automatic gain control HITACHI Ltd 25 Nov 1974 [26 Nov 1973] 50986/74 Heading H3T A television a.g.c. system comprises means for amplifying the television signal containing a composite video signal, means for detecting the composite video signal, a sync. separator, means for modifying the composite video signal so that the pedestal is the most black level and an a.g.c. signal generator connected between the modifying means and the amplifying means to control the gain thereof. The video signal with negative going sync. pulses from the first video amplifier 4, Fig. 1, is connected to a sync. separator transistor 10 and through a switch 103 to an A.G.C. detector transistor 16. A pulse (b) from the sync. separator cancels the sync. pulse, leaving the black level pedestal the most negative going portion of the signal applied to transistor 16. Transistor 16 is biased to just conduct near the tip of the pedestal so that changes in pedestal level change the collector current to develop an A.G.C. voltage across resistor 23. Diode 14 may be replaced by a transistor with resistor 15 connected to its base, Fig. 3 (not shown).
GB5098674A 1973-11-26 1974-11-25 Automatic gain control circuit Expired GB1493264A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13171073A JPS5435734B2 (en) 1973-11-26 1973-11-26

Publications (1)

Publication Number Publication Date
GB1493264A true GB1493264A (en) 1977-11-30

Family

ID=15064374

Family Applications (1)

Application Number Title Priority Date Filing Date
GB5098674A Expired GB1493264A (en) 1973-11-26 1974-11-25 Automatic gain control circuit

Country Status (5)

Country Link
JP (1) JPS5435734B2 (en)
CA (1) CA1050160A (en)
DE (1) DE2455703C3 (en)
FR (1) FR2252717B1 (en)
GB (1) GB1493264A (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50125627A (en) * 1974-03-19 1975-10-02
JPS5453921A (en) * 1977-10-07 1979-04-27 Clarion Co Ltd Automatic gain control circuit for am receiver
JPS5510277A (en) * 1978-07-07 1980-01-24 Matsushita Electric Ind Co Ltd Agc circuit

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE559382A (en) * 1956-07-20
JPS5319709Y2 (en) * 1971-03-22 1978-05-25

Also Published As

Publication number Publication date
FR2252717A1 (en) 1975-06-20
JPS5435734B2 (en) 1979-11-05
JPS5084132A (en) 1975-07-07
CA1050160A (en) 1979-03-06
DE2455703C3 (en) 1978-03-16
FR2252717B1 (en) 1982-03-19
DE2455703B2 (en) 1977-07-28
DE2455703A1 (en) 1975-06-19

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Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee