| 摘要 |
PURPOSE:To discriminate whether a magnetic recording medium recorded with data is a reproduced medium or not by providing regions where information to read out ID field parts and data field parts continuously is recorded and regions where information to detect phase deviations at the junction points of the data field parts is recorded to said medium. CONSTITUTION:The ID field parts and the data field parts are previously recorded continuously on the magnetic recording medium which is the original. Reading of the data is so assigned as to read out the ID field part 11 and the data field parts 12 continuous to the region of the magnetic recording medium where the reading of the data is first executed. The means for previously recording this program and the program to detect the phase deviation at the junction point of the data fields 21 is provided. Discrimination can be made that the magnetic recording medium is the reproduced medium when the phase deviation is detected by this means. Whether the magnetic recording medium is the original or copy or whether the data field parts are rewritten or not is thereby discriminated. |
