| 摘要 |
PURPOSE:To prevent production of erroneous demodulation result by setting a prescribed proper range within a range able to correct a phase difference to limit the correction even when a phase of an input signal is largely fluctuated in a positive/negative way. CONSTITUTION:A phase of a demodulation result from an external phase discrimination circuit 13 and a phase of an expected value from other phase discrimination circuit 15 are stored respectively in areas x, y in a RAM. Then the phase difference is calculated to obtain an input and an absolute value and a threshold value are compared by a phase comparator 16. In the case of absolute value < threshold value, the input value is outputted to an external phase control circuit 17 as a correction value. Furthermore, in the case of absolute value > threshold value, the threshold value is outputted to the external phase control circuit 17 as an output value. That is, when the input stays within a positive/ negative threshold level, the proportional relation is in existence and when the threshold level is exceeded, the output is fixed to a maximum value to be taken within a range that the output is within the positive negative threshold level. As a result, even when the phase of the input signal is fluctuated in both polarities, production of erroneous demodulation result is prevented. |
