| 摘要 |
PURPOSE: A symbol timing synchronization device using a timing synchronization loop control unit for a multi-level modulation method and a synchronizing method thereof are provided to reduce the distribution of error values according to S/N ratio and reduce the amount of jitter in a tracking process by outputting a timing error according to changing states of signs. CONSTITUTION: A symbol timing synchronization device using a timing synchronization loop control unit for a multi-level modulation method includes a first to a fourth calculation unit, a first to a fourth quantization unit, a first and a second code detection unit, a zero-crossing detection unit, and a timing error control unit(33). The first to the fourth calculation units(401,402,405,406) calculate timing errors between input timing and sampling timing of external digital signals. The first to the fourth quantization units(403,404,407,408) control the direction and the magnitude of the timing errors. The first and the second code detection units(409,410) detect the variation of codes according to the results of the first to the fourth quantization units. The zero-crossing detection unit detects the zero-crossing of an I-axis and a Q-axis according to the results of the first and the second code detection units. The timing error control unit controls the timing error output values when the codes are not varied.
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