Patent ID: 6066982
Filing Date: 2000-05-23
Classification: H03K,H03L,H04L

Abstract:
A phase locked loop apparatus for demodulating a pulse signal, which transmits information depending on whether an information pulse having a pulse width within a certain range is present or not, the apparatus periodically generating a reproduction clock signal with a reference pulse width to demodulate the pulse signal and controlling a phase of the reproduction clock signal to detect whether the information pulse is present or not in the pulse signal at a predetermined timing of change in waveform of the reproduction clock signal, the apparatus comprising:motion clock generating means for generating a motion clock signal having a predetermined period of two or more natural numbers corresponding to the reference pulse width;pulse detecting means for comparing a result of sampling of the pulse signal to be demodulated, based on the motion clock signal from said motion clock generating means, with a plurality of patterns expected based on fluctuations in pulse width of the information pulse in the pulse signal and fluctuations in phase of the information pulse in the pulse signal and the motion clock signal, to detect whether the information pulse is present or not, according to presence or absence of any pattern matching with the sampling result;reproduction clock generating means for generating the reproduction clock signal; andphase comparing means for comparing the phase of the information pulse in the pulse signal which is used by said pulse detecting means as being present in the pulse signal with that of the reproduction clock signal generated from said reproduction clock generating means, and carrying out phase control of said reproduction clock generating means according to a comparison result.