Abstract: Methods and apparatus for encoding compressed data streams efficiently, and methods and apparatus for decoding the encrypted data streams efficiently and inexpensively, are disclosed. In an encoder 10', an incoming data stream is fed to a Huffman coding block 10 that performs data compression. The output codewords of the Huffman coding block are fed to a forward error correction block 30, the output of which is a series of data blocks and associated parity data. The data blocks are fed to an error insertion block 32, which inserts a one-bit error in each data block. The parity data is fed to a first encryption block 34 that produces encrypted parity data. The output of the error insertion block 32, the encrypted parity data, and a synchronization word output by a sync generator 50 are fed to a multiplexer 48. A seed generator block 36 generates random numbers for use by the first encryption block 34 as seeds for encrypting the parity data.

Abstract: The present invention discloses a method and apparatus for providing a cable TV system with the ability to issue information from a system manager, determine whether the information is intended for a set top designed to receive out-of-band information or in-band information, send the information to the appropriate circuitry. Reformatting of some information is necessary and is performed by a format translator. For in-band information, information may be sent over one or more of a plurality of data streams. Certain types of information are sent over one or more data streams based on the type of information and characteristics of the data streams. It is further disclosed that for efficiency, similar information intended for several addresses is grouped together in a database manager so that the information may be sent to plural addresses at one time. Scramblers are employed with the capability of inserting data onto nonscrambled channels.