| 摘要 |
The disclosed system comprises a disc-shaped information carrier (1) and an apparatus for reading and writing information blocks in a continuous track (9). For indicating the track (9), the information carrier (1) has a servotrack (4) in which a winding number is encoded per track winding (3). A winding number and an angular position can be determined from the address of an information block. The angular position is given relative to a reference angular position. This reference angular position is determined by one or more reference marks (21, 22) which are written on the information carrier (1) prior to the first information block. The actual angular position is determined by counting the time relative to a known rotation time from the reading of a reference mark (21, 22) onwards. One or more pulses, for example tachopulses, are generated per revolution in the apparatus. The location of the reference angular position is determined relative to the pulses by reading a reference mark (21, 22) and, subsequently, the actual angular position can be derived from the pulses. |
