| 摘要 |
PURPOSE:To attain comparatively simply the EFM demodulation with a small capacity ROM by utilizing one of properties of an EFM signal of 14-bit per one word that its run length is >=3. CONSTITUTION:Output signals b0-b7 of a latch circuit 4 are used for an address input to the ROM of (256X5)-bit, which outputs 5-bit codes d0-d4 corresponding to 28 kinds of code patterns permitted as the EFM signal in consecutive 8-bit codes. Further, OR gates 51-54 input signals b8-b13 in the output signal of the latch circuit 4 and output bit codes d5-d8. Then the 9-bit code is used as an address and written in the ROM of 512-byte and the 9-bit code corresponding to the EFM signal is used as an EFM demodulation signal of 8-bit code. |
