| 摘要 |
The method for indicating a sector on an optical disc (9) uses a reference (16) of M multiplets, each comprising L bits. A succession of multiplets is engraved locally at this sector on the disc. Engraving may be effected by either modifying the amplitude of the wave period of a 'groove' on the information support or by multiplying by three an initial wave frequency over the total period of the initial alternation. The method for indicating a sector on a data medium such as an optical disc (9) uses a reference (16) which consists of M multiplets, each comprising L bits. Locally at this sector on the disc a succession of multiplets is engraved. These each correspond to a first multiplet, and a second multiplet which is equal to a vector of N components, each of value +1 or -1, such that N = 2L-1, and also such that the scalar product of the vector by any other vector which is equal to another second multiplet, is not more than a+1. One of the +1 or -1 values is engraved by modifying the amplitude of the wave period of a 'groove' on the information support. One of the +1 or -1 values may be engraved by multiplying by three an initial wave frequency over the total period of the initial alternation.
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