| 摘要 |
PURPOSE:To improve economy by facilitating backward reading operation by utilizing a preamble, a postamble, and a mark. CONSTITUTION:An encoding circuit 1 encodes the data part and check part of input data Bi. The encoding output is given a preamble, a mark, and resink by a modulating circuit 2 for MFM modulation. The output of the circuit 2 is recorded by a writing head 3. Read data from a read head 4, on the other hand, is supplied to a PLL circuit 5 to generate a clock for discrimination. A demodulating circuit 6 performs the MFM demodulation of the output of the circuit 5 to extract only the data and a check code. Then, an error correcting circuit 7 generates a syndrome to correct error data and also makes a CRC check to output only corrected data B'i. |
