| 摘要 |
PURPOSE:To draw in the timing reproduction of phase modulated waves received in the form of burst at a high speed under a low C/N condition by constituting the '0' and '1' alternate pattern extracting circuit at the leading edge section of burst waves as a narrow-band filter with the Nyquist frequency of demodulated base band signals as the center frequency. CONSTITUTION:The orthogonal and same-phase signals of the demodulated base band signals 1 of received waves become the phase difference information with the reference clock 10 of a timing reproducing system PLL 3 after the signals are supplied to a phase comparator 2 and this information is inputted as the phase controlling information of the reference clock 10 of the PLL 3. At the timing reproducing system PLL 3, operations under a low C/N condition are compensated by suppressing an inter-PLL noise band width to the utmost and high-speed drawing-in operations are coped with by means of a timing extracting circuit 4 at the outside of the PLL 3. The timing component extracting circuit 4 is constituted of, for example, a band-pass filter which uses the Nyquist frequency of the demodulated base band signals 1 as its center frequency and has a high Q. |
