| 摘要 |
PURPOSE:To reduce the lowering of response and following errors with the discrimination gain kept constant, by providing a level divider capable of setting the FM modulation range of VCO at several stages and a level changer to obtain the optimum FM modulation range according to a signal. CONSTITUTION:An input frequency is mixed 9a with a local frequency and the frequency of the difference is taken out 9b to be detected 9c. Then, the frequency of the difference is discriminated 9d and integrated 9e. An addition signal of the output of an oscillator 9h and the output signal of the integrator 9e is inputted into a voltage control oscillator 9g to output a local frequency following the input frequency. The frequency tracking apparatus thus obtained is provided with a level divider 9m capable of setting the FM modulation range DELTAfv of the voltage control oscillator 9g and a level changer 9n for changing each level to obtain the optimum FM modulation range DELTAfv easily corresponding to a signal Q. |
