| 摘要 |
PURPOSE:To attain the high density of magnetic recording by realizing self- clocking and at the same time reducing greatly the maximum magnetization inverting interval while maintaining the performance of 3PM. CONSTITUTION:An FEM-4 converts the data of 4 bits into a code word of 8 bits and then modulates the series of the code word by an NRZI. For the 1st rule of modulation of the FEM-4, the 8th bit P8 of a code word which is old in terms of time series is inverted to bit ''1'' in case the next two continuous binary data of 4 bits are combined. Then the 3rd bit P3 of the following code word is inverted to bit ''1''. For the 3rd rule of modultion of the FEM-4, the 2nd code word P1P2P3P4P5P6P7P8 and 00001000 are allowed to correspond to the 2nd data ''O'' which is set at the center in terms of time series in the case a combination of the next three continuous binary data. Here a conversion table of modulation method (FEM-5) is shown for this invention. The 1st rule of modulation of the FEM-5 is equal to the 1st rule of modulation of the FEM-4, and the 2nd rule of modulation of the FEM-5 is equal to the FEM-4. Then the 3rd rule of modulation of the FEM-5 corresponds to the 3rd modulation rule of the FEM-4. |
