Modulation device and demodulation device and methods of the same

摘要

A modulation device and a demodulation device suitably performing DSV control while reducing the size and lowering the price of the hardware. Recording data is modulated at a modulator. In a DSV calculator, the DSV value of a modulated data is calculated in units of 1 DSV frame. A comparator outputs a sign comparison result of a DSV value cumulatively added from the start of recording and a DSV value to a DSV control bit insertion unit. The DSV control bit insertion unit inserts bits of DSV control data in accordance with the comparison result at a predetermined insertion position of the modulated data delayed by exactly an amount of 1 DSV frame. Thereafter, the modulated data is subjected to NRZ modulation.