Communications format for a subscription television system permitting transmission of individual text messages to subscribers
First Claim
1. A method of transmitting individual data in packets to plural decoders of a television subscription system, each decoder receiving the same addressed data packet, said method comprising the steps of:
- assigning groups of decoders to membership in banks of decoders;
assigning a bank identification number address to all decoders in a given bank of decoders;
assigning an individual member code comprising n bits to each of the decoders in each bank;
transmitting an addressed data packet including said bank identification number address to the decoders of said bank, said data packet including a data field, said data field having a predetermined format of at least 2n packet enable bits wherein the number of packet enable bits 2n is equal to or greater than the number of decoders assigned to a given bank, values of said bits in said data field being assigned to convey data to be transmitted to said plural decoders; and
using said individual member code to point to one or more packet enable bits in said data field for status interpretation at said decoder to which said individual member code is assigned.
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Accused Products
Abstract
A subscription television system in which individual decoders are enabled to receive individually addressed messages is disclosed. The composite signal, including video and teletext, also comprises addressed packets which are detected by decoders and which indicate that a message addressed to a particular subscriber is forthcoming, and system control data. In a preferred embodiment, both addressed packets and teletext are encrypted. The addressed packet is decrypted using a decoder-specific code and a transmitted code, while the teletext message is decrypted using a decryption key contained in the system control data. The teletext message cannot be received until the addressed packet has been decrypted. Therefore, redundant levels of security are provided to the system. Messages for display to the user can be selected in response to user initiated commands, in response to decoder initiation, or in response to the transmitter.
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Citations
13 Claims
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1. A method of transmitting individual data in packets to plural decoders of a television subscription system, each decoder receiving the same addressed data packet, said method comprising the steps of:
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assigning groups of decoders to membership in banks of decoders; assigning a bank identification number address to all decoders in a given bank of decoders; assigning an individual member code comprising n bits to each of the decoders in each bank; transmitting an addressed data packet including said bank identification number address to the decoders of said bank, said data packet including a data field, said data field having a predetermined format of at least 2n packet enable bits wherein the number of packet enable bits 2n is equal to or greater than the number of decoders assigned to a given bank, values of said bits in said data field being assigned to convey data to be transmitted to said plural decoders; and using said individual member code to point to one or more packet enable bits in said data field for status interpretation at said decoder to which said individual member code is assigned. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A television subscription system capable of transmitting individual data to a plurality of decoders, the plurality of decoders being arranged individually or in banks of decoders, each decoder receiving the same addressed message, said system comprising:
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transmission means for transmitting individual data to a plurality of decoders, said transmission means capable of transmitting an addressed message, said addressed message including a bank identification number address and a data field having a predetermined format of bits, wherein the number of bits in the data field is equal to or greater than the number of decoders assigned to a given bank, values of the bits in the data field being assigned in accordance with data to be transmitted to specific individual decoders; and a plurality of decoders, each of said plurality of decoders comprising; individual member code storage means for storing an individual member code assigned to a given decoder; bank identification storage means for storing a bank identification number which may be assigned to a given decoder; and message reception means connected to the transmission means, the individual member code storage means and the bank identification number storage means for receiving addressed message data sent from the transmission means to the decoders, said message reception means recognizing selected bits in the data field, recognition being performed using the individual member code stored in the individual member code storage means of said given decoder to identify in said data field at least one bit intended for said given decoder assigned to the individual member code.
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Specification