The erasable optical disk with high recording density, high stability, high data transfer rate, high carrier-noise ratio and low error rate arc the main points in the research and development.

From signal to noise ratio analysis of the modulation signal, we choose the phase modulation method as the suitable carrier modulation for the twisted-pair.

But to the CW pulse signal with changing carrier wave frequency, common filter cannot achieve narrowband filter, whereas broadband filter cannot reach the request of the signal-noise ratio.