| 摘要 |
<p>There are included a complex sinusoidal wave generating circuit (3) for generating a complex sinusoidal wave; a multiplying circuit (4) for multiplying an input signal by the complex sinusoidal wave; a first integrating circuit (5) for integrating the multiplication results of the multiplying circuit (4) in the time direction; a first square circuit (6) for determining a square of the absolute value of a complex signal that is an output signal of the first integrating circuit (5); a second square circuit (7) for determining a square of the absolute value of an instantaneous amplitude of the input signal; a second integrating circuit (8) for integrating the calculation results of the second square circuit (7) in the time direction; and a frequency difference calculating circuit (9) for calculating, based on the ratio of the output signal level of the first square circuit (6) to the output signal level of the second integrating circuit (8), the difference between the frequency of the input signal and the oscillation frequency of the complex sinusoidal wave. In this way, there can be obtained a frequency difference detecting apparatus capable of detecting, with high precision, the frequency difference between the frequency of an input signal and a predetermined reference frequency even when the input signal includes many noises.</p> |
