EP0123422A2
Expired / Lapsed
EP
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Apparatus for scrambling and unscrambling signals
Assignee: Plessey Overseas Ltd
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Filing: 1984-03-21
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Granted: —
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Expires: 2004-03-21
Abstract
Abstract An apparatus for scrambling rasterscan lines of a multiplex analogue component television signal having luminance and chrominance sections in analogue form comprises a writing means (W1), a luminance store (4) and a chrominance store (5), and a reading means (R1). A controlling means (6) controls the writing means (W1) so thatthe luminance section of the signal is written into the luminance store (4) and the chrominance section is written into the chrominance store (5). The controlling means (6) then controls the reading means (R1) to produce a scrambled signal in which one of the analogue sections is divided into a plurality of information blocks which are separated by at least a part of the other analogue section. An unscrambling apparatus for unscrambling the signal scrambled by the above apparatus comprises a writing means (W3) which is controlled by a controlling means (15) to write the luminance information blocks into a luminance store (17) and the chrominance information into a chrominance store (18). A reading means (R4) is controlled by the controlling means (15) to read out the stores (17, 18) to provide undivided sections of analogue chrominance and luminance information.
Inventors
- 👤 John Norman Gooding
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 11:09
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/169; H04N7/1696; H04N7/1675
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
96 words
An apparatus for scrambling a signal having first and second sections of analogue information, the apparatus comprising writing means for writing the first section into a first store and for writing the second section into a second store, reading means for reading out the stores, and controlling means for controlling the writing and the reading out to produce a signal in which at least one of the sections of analogue information is divided into a plurality of information blocks which information blocks are separated by at least a part of the other section of analogue information.
Claim 2
Independent Claim
96 words
An apparatus for scrambling a signal having first and second sections of analogue information, the apparatus comprising writing means for writing the first section into a first store and for writing the second section into a second store, reading means for reading out the stores, and controlling means for controlling the writing and the reading out to produce a signal in which at least one of the sections of analogue information is divided into a plurality of information blocks which information blocks are separated by at least a part of the other section of analogue information.
Claim 3
Dependent Claim
36 words
An apparatus according to claim 1 wherein the signal is a television signal having in each a raster scan line a section of digital information in addition to the first and second sections of analogue information.
Claim 4
Dependent Claim
41 words
An apparatus according to claim 1 or claim 2, wherein a sampling means is provided for sampling the first and second sections of analogue information prior to the first and second sections being written into the first and the second stores.
Claim 5
Dependent Claim
49 words
An apparatus according to claim 2 or claim 3, wherein a synchronising means is provided to receive the television signal, to separate the section of digital intormation from the first and second sections of analogue information, and to provide a synchronising signal in response to each raster scan line.
Claim 6
Dependent Claim
36 words
An apparatus according to claim 4, wherein the controlling means is arranged to receive the synchronising signal and to provide a key signal representative of the division of the at least one section ot analogue information.
Claim 7
Dependent Claim
31 words
An apparatus according to claim 5, wherein a key signal encoding means is provided to combine the key signal with the section of digital information to provide an encoded digital signal.
Claim 8
Dependent Claim
38 words
An apparatus according to claim 6, wherein a combining means is provided to combine the encoded digital signal with the analogue information blocks fed out from the first and second stores thereby to provide a scrambled television signal.
Claim 9
Dependent Claim
121 words
An apparatus according to claim 7, wherein a second writing means is provided for writing the sampled tirst section into a third store and for writing the sampled second section into a fourth store, a second reading means is provided for reading out the third and fourth stores, a directing means is provided which is operative to direct the sampled first and second sections of analogue information to either of the first or second writing means, and a second directing means is provided and is operative to direct the analogue information blocks trom either the tirst or second reading means to the combining means, and the second reading means and the second writing means are each controlled by the controlling means.
Claim 10
Dependent Claim
88 words
An apparatus according to claim 8 wherein the first and second directing means are arranged to direct the sampled first and second sections of analogue information of one set of alternate raster scan lines to the first writing means at the same time as the second directing means directs the analogue information blocks of the other set of alternate raster scan lines from the second reading means, the first and second directing means being responsive to the synchronisation signal and being switched in antiphase relative to one another.
Claim 11
Independent Claim
117 words
An apparatus for unscrambling a signal having first and second sections of analogue information sections in which at least one of the sections of analogue information is divided into a plurality of information blocks which information blocks are separated by at least a part of the other section of analogue information, the apparatus comprising writing means for writing the information blocks of at least one section of analogue information into a first store and for writing the other section of analogue information into a second store, reading means for reading out the stores, and controlling means for reading out to produce a signal in which each ot the first and second sections of analogue information are undivided.
Claim 12
Independent Claim
117 words
An apparatus for unscrambling a signal having first and second sections of analogue information sections in which at least one of the sections of analogue information is divided into a plurality of information blocks which information blocks are separated by at least a part of the other section of analogue information, the apparatus comprising writing means for writing the information blocks of at least one section of analogue information into a first store and for writing the other section of analogue information into a second store, reading means for reading out the stores, and controlling means for reading out to produce a signal in which each ot the first and second sections of analogue information are undivided.
Claim 13
Dependent Claim
24 words
An apparatus according to claim 10, wherein the signal is a television signal having a section of digital information in each raster scan line.
Claim 14
Dependent Claim
50 words
An apparatus according to claim 11, wherein a synchronising means is provided to receive the scrambled television signal and to provide a synchronising signal in response to each raster scan line, and to separate the first and the second sections of analogue information blocks from the section of digital information.
Claim 15
Dependent Claim
46 words
An apparatus according to claim 12, wherein a key signal decoding means is provided to decode the section of digital information to provide a key signal representative of the division of information blocks in the scrambled television signal, and to provide a section of digital information.
Claim 16
Dependent Claim
46 words
An apparatus according to claim 13 wherein a controlling means is arranged to control the writing and reading out in response to the synchronising signal and the key signal, thereby to cause undivided first and second sections of analogue information to emerge from the reading means.
Claim 17
Dependent Claim
34 words
An apparatus according to claim 14 wherein a combining means is provided for combining the section of digital intormation with the signal read out from the reading means to produce the unscrambled television signal.
Claim 18
Dependent Claim
112 words
An apparatus according to claim 15 wherein a second writing means is provided for writing the intormation blocks of the first section of analogue information into a third store and for writing the information blocks of the second section of analogue information into a fourth store, a second reading means is also provided for reading out the third and fourth stores, and directing means is provided to direct the first and second analogue information blocks to either the first writing means or the second writing neans, and a second directing means is provided to direct the undivided section of analogue information from either the first reading means or the second reading means.
Claim 19
Dependent Claim
84 words
An apparatus according to claim 17 wherein the first and second directing means respond to the synchronising signal so that the first directing means directs the first and second sections of analogue information blocks of one set of alternate raster scan lines to the first writing means at the same time as the second directing means directs the undivided first and second sections of analogue information of the other set of alternate raster scan lines from the second reading means to the combining means.
Claim 20
Independent Claim
30 words
An apparatus according to any one of the preceding claims wherein the first and second analogue sections are chrominance and luminance sections respectively of a multiplex analogue component (MAC) signal.
Claim 21
Independent Claim
26 words
An apparatus according to any one of the preceding claims, wherein the first, second, third and fourth stores are in the form of charged coupled devices.
Claim 22
Independent Claim
26 words
An apparatus according to any one of claims 1 to 19, wherein the first, second, third and fourth stores are in the form of digital memories.
References Cited (Backward Citations)
No citation records indexed.
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