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GB902475A - Improvements in clamp circuits for television signals - Google Patents

Improvements in clamp circuits for television signals

Info

Publication number
GB902475A
GB902475A GB26560A GB26560A GB902475A GB 902475 A GB902475 A GB 902475A GB 26560 A GB26560 A GB 26560A GB 26560 A GB26560 A GB 26560A GB 902475 A GB902475 A GB 902475A
Authority
GB
United Kingdom
Prior art keywords
pulses
circuit
clamp
television
circuits
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
GB26560A
Inventor
David Christopher Savage
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.)
British Broadcasting Corp
Original Assignee
British Broadcasting Corp
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 British Broadcasting Corp filed Critical British Broadcasting Corp
Priority to GB26560A priority Critical patent/GB902475A/en
Publication of GB902475A publication Critical patent/GB902475A/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
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of DC and slowly varying components of signal; Circuitry for preservation of black or white level
    • H04N5/18—Circuitry for reinsertion of DC and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit
    • H04N5/185—Circuitry for reinsertion of DC and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit for the black level

Landscapes

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

Abstract

902,475. Television. BRITISH BROADCASTING CORPORATION. Jan. 3, 1961 [Jan. 4, 1960], No. 265/60. Class 40 (3). [Also in Group XL (c)] The time constant of a resistance-capacitance circuit employed in a television signal clamp circuit to average interference over the duration of the clamping pulses is varied directly as the amplitude of such interference. Figs. 1 and 2 show two clamp circuits suitable for use with the present invention, these circuits operating to clamp television signals at point A (from input terminal 10) to a reference potential by means of a switch 13 operated during the back-porch of the line synchronizing pulses by means of clamping pulses from a generator 15 and both circuits including a resistancecapacitance circuit R, C. In the described embodiment of the invention the resistance R is constituted by a thermistor R (Fig. 3), the heating element 26 of which forms the cathode circuit of a cathode-follower 25 driven by the amplified (23) and rectified (24) noise signals 20 which occur during the back-porch 21 of the television signal 19, the noise signals being separated out by means of a sampling bridge controlled by pulses 18 and supplied to a B.P.F. having cut-off frequencies of 1.2 and 1.8 x line frequency. A second thermistor 27 serves to compensate for changes in ambient temperature. Specification 883,694 is referred to.
GB26560A 1960-01-04 1960-01-04 Improvements in clamp circuits for television signals Expired GB902475A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB26560A GB902475A (en) 1960-01-04 1960-01-04 Improvements in clamp circuits for television signals

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB26560A GB902475A (en) 1960-01-04 1960-01-04 Improvements in clamp circuits for television signals

Publications (1)

Publication Number Publication Date
GB902475A true GB902475A (en) 1962-08-01

Family

ID=9701314

Family Applications (1)

Application Number Title Priority Date Filing Date
GB26560A Expired GB902475A (en) 1960-01-04 1960-01-04 Improvements in clamp circuits for television signals

Country Status (1)

Country Link
GB (1) GB902475A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4122492A (en) * 1977-01-28 1978-10-24 Ampex Corporation DC restoration utilizing the color burst signal
US4516042A (en) * 1982-06-30 1985-05-07 Tektronix, Inc. Clamp circuits

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4122492A (en) * 1977-01-28 1978-10-24 Ampex Corporation DC restoration utilizing the color burst signal
US4516042A (en) * 1982-06-30 1985-05-07 Tektronix, Inc. Clamp circuits

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