GB1362131A - Reducing unwanted modulation in a communication system - Google Patents

Reducing unwanted modulation in a communication system

Info

Publication number
GB1362131A
GB1362131A GB722272A GB722272A GB1362131A GB 1362131 A GB1362131 A GB 1362131A GB 722272 A GB722272 A GB 722272A GB 722272 A GB722272 A GB 722272A GB 1362131 A GB1362131 A GB 1362131A
Authority
GB
United Kingdom
Prior art keywords
filter
signal
modulation
frequency
rejected
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
GB722272A
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.)
Post Office
Original Assignee
Post Office
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 Post Office filed Critical Post Office
Priority to GB722272A priority Critical patent/GB1362131A/en
Priority to NL7301427A priority patent/NL7301427A/xx
Priority to BE795302D priority patent/BE795302A/en
Priority to JP48018836A priority patent/JPS4890613A/ja
Priority to CA164,139A priority patent/CA964388A/en
Priority to FR7305329A priority patent/FR2172268B1/fr
Priority to DE19732307806 priority patent/DE2307806A1/en
Publication of GB1362131A publication Critical patent/GB1362131A/en
Priority to GB755674A priority patent/GB1464113A/en
Priority to GB644675A priority patent/GB1464114A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D1/00—Demodulation of amplitude-modulated oscillations
    • H03D1/02—Details
    • H03D1/04—Modifications of demodulators to reduce interference by undesired signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/80—Camera processing pipelines; Components thereof
    • H04N23/81—Camera processing pipelines; Components thereof for suppressing or minimising disturbance in the image signal generation
    • 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
    • H04N5/21—Circuitry for suppressing or minimising disturbance, e.g. moiré or halo

Landscapes

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

Abstract

1362131 Television POST OFFICE 31 Jan 1973 [16 Feb 1972] 7222/72 Heading H4F To reduce unwanted amplitude modulation of a communications signal, e.g. that on the output video signal of a television camera operating at 60 fields per second, but viewing a scene illuminated by lighting varying at a mains rate of 100 c./s., i.e. twice mains frequency, the modulated signal is fed to an analogue divider circuit 1 for division by the modulation signal (input 10) derived from the divider output via a signal level-e.g. black level-clamp 3, a high gain amplifier 6 and a filter 7. The modulations of the video signal f(t) can be represented by a multiplying factor A (1 + m Sin wt), w being the modulating frequency, such that the modulation can be removed by the division of the modulated signal by the factor. The modulation frequency is extracted by the filter 7 which is a commutating N-path filter passing 100 c./s. and its harmonics. The third harmonic 300 c./s., being the 5th harmonic of the field rate is present and thus has to be rejected by a twin-T band stop filter 13 (an elliptical filter also being possible). Components introduced by. the sampling in filter 7 are rejected by a 4th order Butterworth filter 8. The signal Sin wt so extracted has the bias signal A added to it by bias amplitude control circuit 9. The divider circuit comprises an operational amplifier 15 having a trans-conductance multiplier 14 in its feedback loop.
GB722272A 1972-02-16 1972-02-16 Reducing unwanted modulation in a communication system Expired GB1362131A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
GB722272A GB1362131A (en) 1972-02-16 1972-02-16 Reducing unwanted modulation in a communication system
NL7301427A NL7301427A (en) 1972-02-16 1973-02-01
BE795302D BE795302A (en) 1972-02-16 1973-02-12 IMPROVEMENTS RELATED TO THE REDUCTION OF AN UNDESIRABLE MODULATION IN A TRANSMISSION SYSTEM
JP48018836A JPS4890613A (en) 1972-02-16 1973-02-15
CA164,139A CA964388A (en) 1972-02-16 1973-02-15 Reducing unwanted modulation in a communications system
FR7305329A FR2172268B1 (en) 1972-02-16 1973-02-15
DE19732307806 DE2307806A1 (en) 1972-02-16 1973-02-16 METHOD AND ARRANGEMENT FOR REDUCING UNWANTED MODULATION OF THE AMPLITUDE OF A MODULATED SIGNAL IN A MESSAGE TRANSMISSION SYSTEM
GB755674A GB1464113A (en) 1972-02-16 1975-02-14 Reducing unwanted modulation
GB644675A GB1464114A (en) 1972-02-16 1975-02-14 Reducing unwanted modulation surface

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB722272A GB1362131A (en) 1972-02-16 1972-02-16 Reducing unwanted modulation in a communication system

Publications (1)

Publication Number Publication Date
GB1362131A true GB1362131A (en) 1974-07-30

Family

ID=9828974

Family Applications (3)

Application Number Title Priority Date Filing Date
GB722272A Expired GB1362131A (en) 1972-02-16 1972-02-16 Reducing unwanted modulation in a communication system
GB644675A Expired GB1464114A (en) 1972-02-16 1975-02-14 Reducing unwanted modulation surface
GB755674A Expired GB1464113A (en) 1972-02-16 1975-02-14 Reducing unwanted modulation

Family Applications After (2)

Application Number Title Priority Date Filing Date
GB644675A Expired GB1464114A (en) 1972-02-16 1975-02-14 Reducing unwanted modulation surface
GB755674A Expired GB1464113A (en) 1972-02-16 1975-02-14 Reducing unwanted modulation

Country Status (7)

Country Link
JP (1) JPS4890613A (en)
BE (1) BE795302A (en)
CA (1) CA964388A (en)
DE (1) DE2307806A1 (en)
FR (1) FR2172268B1 (en)
GB (3) GB1362131A (en)
NL (1) NL7301427A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2175172A (en) * 1985-04-30 1986-11-19 British Broadcasting Corp Video cameras

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8403114A (en) * 1984-10-12 1986-05-01 Philips Nv TELEVISION RECORDING SYSTEM OPERATING WITH DIFFERENT ALTERNATING NETWORK FREQUENCY AND TELEVISION GRID FREQUENCY, AND SUITABLE TELEVISION RECORDING EQUIPMENT.

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2137613B1 (en) * 1970-10-23 1973-02-01 Siemens AG, 1000 Berlin u 8000 München CIRCUIT ARRANGEMENT FOR PHONE TELEPHONE TO REMOVE MALFUNCTIONS ON THE SCREEN

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2175172A (en) * 1985-04-30 1986-11-19 British Broadcasting Corp Video cameras

Also Published As

Publication number Publication date
GB1464113A (en) 1977-02-09
BE795302A (en) 1973-05-29
DE2307806A1 (en) 1973-08-30
FR2172268A1 (en) 1973-09-28
GB1464114A (en) 1977-02-09
CA964388A (en) 1975-03-11
FR2172268B1 (en) 1977-02-11
JPS4890613A (en) 1973-11-26
NL7301427A (en) 1973-08-20

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
435 Patent endorsed 'licences of right' on the date specified (sect. 35/1949)
PCNP Patent ceased through non-payment of renewal fee