| 摘要 |
PURPOSE:To reduce an error in a digital output signal and to widen the synchronization lock range when a carrier synchronization is unlocked by identifying the specific sub area only around signal points in an area to which signal points on a diagonal line belong. CONSTITUTION:The circuit is made up of a synchronization discrimination circuit 2 discriminating synchronization of a radio wave signal, A/D converter circuits 18, 19 identifying and A/Dconverting a demodulated 4-value base band signal, and a logic circuit 1 logically discriminating the large error in the digital output signal. Thus, only a phase control signal obtained from signal pints on desired diagonal lines is used to control a voltage controlled oscillator 25 and phase control information obtained from other points than the desired signal point is in holding with a probability of nearly 1/2, then the control signal is replaced into the holding signal. Thus, when the carrier synchronization is deviated, an error in a digital signal is less and the synchronization lock range is expanded. |
