GB1500743A - Decoder for a scrambled tv signal - Google Patents

Decoder for a scrambled tv signal

Info

Publication number
GB1500743A
GB1500743A GB3714675A GB3714675A GB1500743A GB 1500743 A GB1500743 A GB 1500743A GB 3714675 A GB3714675 A GB 3714675A GB 3714675 A GB3714675 A GB 3714675A GB 1500743 A GB1500743 A GB 1500743A
Authority
GB
United Kingdom
Prior art keywords
audio
sine wave
scrambled
carrier
signal
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
GB3714675A
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.)
Oak Industries Inc
Original Assignee
Oak Industries Inc
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 Oak Industries Inc filed Critical Oak Industries Inc
Publication of GB1500743A publication Critical patent/GB1500743A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/16—Analogue secrecy systems; Analogue subscription systems
    • H04N7/167—Systems rendering the television signal unintelligible and subsequently intelligible
    • H04N7/171—Systems operating in the amplitude domain of the television signal
    • H04N7/1713—Systems operating in the amplitude domain of the television signal by modifying synchronisation signals

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)

Abstract

1500743 Scrambled TV reception OAK INDUSTRIES Inc 9 Sept 1975 37146/75 Heading H4R A television signal, scrambled by the addition to the audio and video carriers of a sine wave of greater amplitude on the audio than the video carrier, is descrambled by an RF amplifier 28 having a gain-controlling input receiving a sine wave derived by a detector 48, filter 42, 46 and amplifier 52 from the audio carrier. The video carrier is almost totally corrected but a residual audio carrier distortion remains. The 15À75 kHz added sine wave suppresses horizontal sync. pulses in the TV signal and is omitted during the vertical sync. and equalizing pulse intervals. The receiver shown includes conventional IF stages 12-26 for cable television in unused channels of which the one above that selected at 12 is removed in trap 30. In Fig. 2 (not shown) the descrambler without the cable channel conversion stages 12, 14 is in parallel with a direct path for non-subscription programmes.
GB3714675A 1974-03-15 1975-09-09 Decoder for a scrambled tv signal Expired GB1500743A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US45149074A 1974-03-15 1974-03-15

Publications (1)

Publication Number Publication Date
GB1500743A true GB1500743A (en) 1978-02-08

Family

ID=23792432

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3714675A Expired GB1500743A (en) 1974-03-15 1975-09-09 Decoder for a scrambled tv signal

Country Status (7)

Country Link
BE (1) BE826727A (en)
CH (1) CH575694A5 (en)
DE (2) DE2510348C2 (en)
FI (1) FI67284C (en)
FR (1) FR2264448B1 (en)
GB (1) GB1500743A (en)
NL (1) NL7502883A (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH575694A5 (en) * 1974-03-15 1976-05-14 Oak Industries Inc
FR2385281A2 (en) * 1974-03-15 1978-10-20 Oak Industries Inc Decoder for subscription cable TV system - removes sinusoidal noise signal unequally from audio and video intermediate frequency signals
US4145717A (en) * 1977-05-11 1979-03-20 Oak Industries Inc. Subscription TV audio carrier recovery system
US4112464A (en) * 1977-05-11 1978-09-05 Oak Industries Inc. Subscription TV decoder logic system
US4353088A (en) * 1980-05-14 1982-10-05 Oak Industries, Inc. Coding and decoding system for video and audio signals
US4336553A (en) * 1980-05-14 1982-06-22 Oak Industries Method of coding audio and video signals

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081376A (en) * 1959-03-23 1963-03-12 Zenith Radio Corp Subscription television system
US3333198A (en) * 1965-12-29 1967-07-25 Ampli Vision Corp Television converter for catv system
US3729576A (en) * 1971-02-08 1973-04-24 Optical Sys Corp Encoding and decoding system for catv
CH575694A5 (en) * 1974-03-15 1976-05-14 Oak Industries Inc

Also Published As

Publication number Publication date
FR2264448A1 (en) 1975-10-10
NL7502883A (en) 1975-09-17
DE2711756A1 (en) 1978-09-21
FI750683A (en) 1975-09-16
DE2510348A1 (en) 1975-09-18
FR2264448B1 (en) 1979-03-30
FI67284B (en) 1984-10-31
DE2711756C2 (en) 1984-03-01
BE826727A (en) 1975-06-30
FI67284C (en) 1985-02-11
CH575694A5 (en) 1976-05-14
DE2510348C2 (en) 1983-11-03

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Legal Events

Date Code Title Description
PS Patent sealed
PE20 Patent expired after termination of 20 years

Effective date: 19950908