| 摘要 |
PROBLEM TO BE SOLVED: To prevent the erroneous judgement of a multi-level digital signal by automatically correcting the center frequency of an intermediate frequency signal by means of following the fluctuations of the characteristic of an FM demodulating circuit part by means of following the fluctuations. SOLUTION: A receiver is provided with a signal detecting part 50 for detecting a specified signal in the intermediate frequency signal and recognizing the start and end of the specified signal and an arithmetic part 42 which stores the max. value and the min. value of the specified signal till the recognition of the end of the specified signal and calculates center value voltage data from an intermediate amplitude voltage value and a reference voltage value which are obtained based on them. In this case, a crystal oscillating part 20 controls an oscillation frequency to be inputted to a mixer 16 for outputting an intermediate frequency signal based on the center value voltage data which is obtained by the arithmetic part 42. |
