| 摘要 |
PURPOSE: A restoring device of a carrier is provided to promote the optimum carrier restoration by calculating the maximum/minimum values from the output of a loop filter and detecting the fixed quantity of FM(Frequency Modulation) hum with the difference. CONSTITUTION: An FM hum detector(400) consists of an FM hum calculator(401) detecting the fixed quantity of FM hum from units by receiving the frequency offset of a carrier from a loop filter(300) and the FM hum from a digital broadcasting receiver, a comparator(402) comparing the output of the FM hum calculator with pre-saved reference FM hum, and a reliability counter(403) checking and outputting the reliability of the comparator to a lock detector(500). The fixed quantity of FM hum is detected by a minimum-maximum algorithm, and the bandwidth of the loop filter is set in proportion to the fixed quantity. Therefore, the restoration capability of FM hum is improved.
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