| 摘要 |
PURPOSE:To reduce the generation of noises to enable a phase wave detection and to prevent the lowering of the tracking accuracy, by converting both the reference and error signals into carrier waves in narrow band and then performing a phase wave detection with use of the carrier wave of a narrow band. CONSTITUTION:A data receiving part 17 converts the frequency through a frequency converter 7 and delivers a demodulation data 19 and a reproduced carrier wave 18 from a time axial waveform 23 which is converted into a signal of a frequency fIF. An adverse modulator 16 gives an adverse modilation to an input error signal 20 by means of a clock, and a data 19 is fed to the modulator 16. Therefore the clock 19 is multiplied by the signal 20 and the phase of the signal 20 is inverted in an inverting period of the clock 19 by an adverse modulating action. As a result, the output 21 delivered from the modulator 16 is turned into a carrier component of the frequency fIF. The error signal which is turned into a narrow band signal after passing through a BPF22 is supplied to phase wave detectors 13 and 14 respectively. Thus a wave detection is possible with suppression of noises. |
