GB806391A - Improvements in circuits for colour television - Google Patents

Improvements in circuits for colour television

Info

Publication number
GB806391A
GB806391A GB2319356A GB2319356A GB806391A GB 806391 A GB806391 A GB 806391A GB 2319356 A GB2319356 A GB 2319356A GB 2319356 A GB2319356 A GB 2319356A GB 806391 A GB806391 A GB 806391A
Authority
GB
United Kingdom
Prior art keywords
luminance signal
sub
band
terminal
modulators
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
GB2319356A
Inventor
William Silvie
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 GB2319356A priority Critical patent/GB806391A/en
Publication of GB806391A publication Critical patent/GB806391A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
    • H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only
    • H04N11/14—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system
    • H04N11/143—Encoding means therefor

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)

Abstract

806,391. Colour television. BRITISH BROADCASTING CORPORATION. June 3, 1957 [July 26, 1956], No. 23193/56. Class 40 (3). Relates to a colour television system utilizing a luminance signal and a chrominance signal which is located within the band of the luminance signal and is in the form of two sub-carriers of the same frequency but having a quadrature phase relationship. At a receiver, when the chrominance signal is detected by means of two synchronous detectors to derive the colour information, components of the luminance signal located at or near the subcarrier are also detected and may prove troublesome in the picture display. In accordance with the invention, this defect is eliminated at the transmitter by suppressing or attenuating the band of luminance frequencies around the sub-carrier frequency. To do this the luminance signal at 10 is applied in parallel to two synchronous detectors 11 and 12, oscillations at sub-carrier frequency being supplied from terminal 13, the connection to detector 11 including a 90 degrees phase-shifter. The detector outputs are derived through lowpass filters 15 and 16 and applied to balanced modulators 17 and 18, which are fed with subcarrier oscillations obtained respectively from phase-shifter 14 and terminal 13. The outputs of the modulators are then added in adding circuit 19 and finally subtracted from the original luminance signal in circuit 20. In effect the components around the sub-carrier frequency it is desired to suppress are shifted to the bottom of the spectrum by detectors 11 and 12, so that they may be selected by low-pass filters 15 and 16, and then restored to their original frequencies by modulators 17 and 18 before subtraction. The arrangement avoids the use of a band-pass filter, which in the particular circumstances is difficult to design. Delay networks 21 and 22 are designed to introduce a delay equal to that produced by filters 15 and 16. Delay network 23 introduces a delay equal to that encountered by the luminance signal in passing through the system from terminal 10 to subtracting circuit 20.
GB2319356A 1956-07-26 1956-07-26 Improvements in circuits for colour television Expired GB806391A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2319356A GB806391A (en) 1956-07-26 1956-07-26 Improvements in circuits for colour television

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2319356A GB806391A (en) 1956-07-26 1956-07-26 Improvements in circuits for colour television

Publications (1)

Publication Number Publication Date
GB806391A true GB806391A (en) 1958-12-23

Family

ID=10191660

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2319356A Expired GB806391A (en) 1956-07-26 1956-07-26 Improvements in circuits for colour television

Country Status (1)

Country Link
GB (1) GB806391A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4731660A (en) * 1987-02-20 1988-03-15 Yves C. Faroudja Processing methods using adaptive threshold for removal of chroma/luminance cross-talk in quadrature-modulated subcarrier color television systems
US5047841A (en) * 1987-03-27 1991-09-10 Robinson Roger N Encoder for television signals
US5070398A (en) * 1988-11-15 1991-12-03 Mitsubishi Denki Kabushiki Kaisha Contour compensator for carrier chrominance signal

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4731660A (en) * 1987-02-20 1988-03-15 Yves C. Faroudja Processing methods using adaptive threshold for removal of chroma/luminance cross-talk in quadrature-modulated subcarrier color television systems
US5047841A (en) * 1987-03-27 1991-09-10 Robinson Roger N Encoder for television signals
US5070398A (en) * 1988-11-15 1991-12-03 Mitsubishi Denki Kabushiki Kaisha Contour compensator for carrier chrominance signal

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