EP0132007A1
Expired / Lapsed
EP
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Authorising coded signals
Assignee: Philips Electronics UK Ltd
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Filing: 1984-07-11
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Granted: —
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Expires: 2004-07-11
Abstract
Abstract In a transmission system authorisation codes are transmitted to authorise subscribers to receive scrambled signals in an intelligible manner, such a system being a television transmission system. If each subscriber were assigned a unique authorisation code an extremely long period would be required to transmit these codes for a national broadcast system. With the present arrangement the authorising code comprises a multi-bit binary code word (18,20) which is unique to a group of subscribers, this codeword being followed by a train of binary pulses (19',19";21',21") the number of pulses in the train being not less than the number of subscribers in the group. Each subscriber is allocated a unique pulse position in the pulse train (19',19";21',21") at which position the state of the pulse either authorises or inhibits the subscriber from receiving the scrambled signal intelligibly.
Inventors
- 👤 Gerald Offley C/O Mullard Limited Crowther
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 11:11
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/1675
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
109 words
A system for authorising a receiver to decode a transmitted scrambled signal in which an authorising code is also transmitted, characterised in that said authorising code comprises a multi-bit binary code word which is unique to a group of subscribers which code word is followed by a train of binary pulses the number of pulses in the train being not less than the number of subscribers in the group, each subscriber being allocated a unique pulse position in said pulse train at which position, depending on the state of the pulse at that position, the subscriber's receiver is either authorised to decode or inhibited from decoding said scrambled signal.
Claim 2
Independent Claim
109 words
A system for authorising a receiver to decode a transmitted scrambled signal in which an authorising code is also transmitted, characterised in that said authorising code comprises a multi-bit binary code word which is unique to a group of subscribers which code word is followed by a train of binary pulses the number of pulses in the train being not less than the number of subscribers in the group, each subscriber being allocated a unique pulse position in said pulse train at which position, depending on the state of the pulse at that position, the subscriber's receiver is either authorised to decode or inhibited from decoding said scrambled signal.
Claim 3
Dependent Claim
106 words
A system as claimed in Claim 1, characterised in that additional multi-bit binary code words are employed each of which is unique to a different group of subscribers, each additional code word being followed by an associated train of binary pulses the number of pulses in the associated train being not less than the number of subscribers in the associated group, each subscriber of said associated group being allocated a unique pulse position in said associated pulse train at which position, depending on the state of the pulse at that position, the subscriber's receiver is either authorised to decode or inhibited from decoding said scrambled signal.
Claim 4
Dependent Claim
41 words
A system as claimed in Claim 2, characterised in that the trains of binary pulses following the code words are not all of the same length such that the respective pulse trains are not associated with the same number of subscribers.
Claim 5
Dependent Claim
68 words
A system as claimed in Claim 1, 2 or 3, characterised in that the or each code word is followed by a binary key code which indicates the location of a further key code contained within the pulse train following the code word, said further key code either indicating the location of an additional key code in said pulse train or the location of the next code word.
Claim 6
Independent Claim
30 words
A system as claimed in any preceding claim, characterised in that said code word or words and associated pulse trains are transmitted prior to the transmission of said scrambled signal.
Claim 7
Independent Claim
30 words
A system as claimed in any preceding claim, characterised in that said code word or words and associated pulse trains are cyclically transmitted during the transmission of said scrambled signal.
Claim 8
Independent Claim
36 words
A system as claimed in any preceding claim in which said scrambled signal is a scrambled television signal, characterised in that said authorising code forms part of the sound and/or data information accompanying said television signal.
Claim 9
Dependent Claim
159 words
A transmitted for use with the system as claimed in any of the proceeding claims, comprising means for providing a signal to be scrambled, means for scrambling said signal, means for applying said scrambled signal to a transmission medium, means for generating subscribers' authorisation codes, and means for applying said authorisation codes to said transmission medium, characterised in that said means for generating said authorisation codes comprises means for generating a multi-bit binary code word which is unique to a group of subscribers and for generating a train of binary pulses to follow said code word, the number of pulses in said pulse train being not less than the number of subscribers in the group, each pulse position in said pulse train being allocated to a respective subscriber in said group and the condition of the pulse at each pulse position indicating whether or not the associated subscriber is authorised to receiver said scrambled signal in an intelligible manner.
Claim 10
Dependent Claim
124 words
A transmitter as claimed in Claim 8, characterised in that said transmitter further comprises means for generating additional multi-bit binary code words each of which is unique to a different group of subscribers and for generating additional trains of binary pulses a different one of which follows a respective additional code word, the number of pulses in each additional pulse train being not less than the number of subscribers in the associated group, each pulse position in said additional pulse trains being allocated to a respective subscriber in the associated group and the condition of the pulse at each pulse position of each additional pulse train indicating whether or not the associated subscriber is authorised to receive said scrambled signal in an intelligible manner.
Claim 11
Dependent Claim
50 words
A transmitter as claimed in Claim 8 or 9, characterised in that said transmitter further comprises means for generating binary key codes for insertion in the or each pulse train which key codes either indicate the location of a further key code or the location of the next code word.
Claim 12
Dependent Claim
40 words
A transmitter as claimed in Claim 8, 9 or 10 in which said signal is a television signal, characterised in that means are provided for inserting said authorisation codes into the sound and/or data information to accompany the television signal.
Claim 13
Dependent Claim
164 words
A receiver for use with the system as claimed in any of the preceding Claims 1 to 7, comprising means for receiving a scrambled signal, means for descrambling said scrambled signal, means for receiving a subscriber's authorisation code and for authorising said descrambling means to descramble said scrambled signal, characterised in that said means for receiving said subscriber's authorisation code comprises means for receiving a transmitted code word or code words and its or their pulse train or trains, means for interrogating the code word or words to determine the presence of the code word associated with the group of which the receiver's subscriber is a part, means for interrogating the pulse train following the said associated code word to determine whether the condition of the pulse at the pulse position in said pulse train allocated to said subscriber authorises said subscriber to receive said scrambled signal in an intelligible manner, and means for enabling said descrambling means should the subscriber be so authorised.
Claim 14
Dependent Claim
45 words
A receiver as claimed in Claim 12, characterised in that said means for interrogating the said pulse train includes means for interrogating key words when inserted in said pulse train to determine which key word is relevant to the pulse position allocated to said subscriber.
Claim 15
Dependent Claim
47 words
A receiver as claimed in Claim 12 or 13, in which said signal is a television signal, characterised in that said means for receiving said subscriber's authorisation code additionally comprises means for separating said authorisation code from the sound and/or data information accompanying with said television signal.
References Cited (Backward Citations)
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