Method and apparatus for generating high rate codes for recording information on a magnetic medium
CA 2185372 C · Owner: Gelblum, Ehud Alexander · Inventors: Gelblum, Ehud Alexander; Calderbank, Arthur Robert
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Method and apparatus for encoding digital information to be recorded on a magnetic medium is disclosed. The invention provides for receiving a sequence of (2mn + d) user bits, mapping the sequence of user bits to 2m dc-free codewords, and recording the 2m dc-free codewords on a magnetic medium. A modulation coder, which includes a memory containing multiple nonintersecting subconstellations of dc-free codewords performs the mapping in a non-equiprobable manner such that a particular codeword from a larger subconstellation is more likely to be used than a particular codeword from a smaller constellation. Less desirable codewords such, as those containing relatively long strings of bits …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed September 12, 1996 and granted October 17, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 12, 2016.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 12, 2018.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.