| 摘要 |
PURPOSE:To generate a phase synchronizing signal of which cycle slip is small and error rate property is good without being affected with phase noise and thermal noise in transmitting by making a loop filter band-variable and controlling a zone based on the intensity of the phase noise generated to an input signal. CONSTITUTION:An input signal which is a modulated wave is two-distributed, one is derived to a carrier reproducing PLL(phase locked loop) circuit constituted of a phase comparator 11, a loop filter 12 and a VCO(voltage control oscillating) circuit 13, and the other is derived to a phase noise detector 14. The above mentioned loop filter 12 can adjust a time constant to decide a band. The oscillating frequency signal of the VCO circuit 13 is outputted as a carrier reproducing signal and is transmitted to the phase noise detector 14 at the same time. The phase noise detector 14 finds relative phase noise intensity from the input signal and the carrier reproducing signal and controls the band of the loop filter 12 corresponding to the phase noise intensity. The band of the loop filter 12 is controlled to a wide band when the phase noise is strong and is controlled to a narrow-band when the phase noise is weak. |
