DATA MODULATION METHOD, DATA MODULATOR, DATA RECORDING DEVICE USING IT, DATA DEMODULATION METHOD, DATA DEMODULATOR AND DATA REPRODUCTION DEVICE USING IT

摘要

PROBLEM TO BE SOLVED: To reduce a DC component of an output data string without much increasing the redundancy based on NRZI modulation. ;SOLUTION: An encoder 31 divides input data WD into blocks for each N-bit and 1-bit data '0' is added to a head of each block and NRZI conversion is conducted. Output data WDM of the encoder 31 are given to a register 32 and output data of the register 32 are fed to a buffer 33 and an inverter 34 and a '0' block and a '1' block outputted respectively are given to a switch circuit 35, from which they are selectively extracted to obtain output data (modulation data) Dr. A selection signal SEL is fed from a selector 38 to the switch circuit 35, and the switch circuit 35 outputs the '0' block or the '1' block so that a sum between a DSV of the recording data Dr of the block and a total sum VA of DSV of the recording data up to a preceding block is close to zero as the recording data Dr of a block succeeding to the preceding block.;COPYRIGHT: (C)1998,JPO