目前国内的无线电话和无线电广播绝大多数是采用调幅,即高频载波的振幅随调制信号的瞬时值而变化.此外我们也可使高频载波的频率或相位随调制信号的瞬时值而变化,这样的调制方式便称为调频或调相.国内电视广播中的伴音信号就是超高频段的调频信号.由于调频具有抗干扰性强、非线性畸变小、发射设备经济有效等一系列优点,因此它在无线电广播和 At present, most of the domestic radiotelephones and radios use amplitude modulation, that is, the amplitude of the high-frequency carrier varies with the instantaneous value of the modulated signal, and in addition, we can also make the frequency or phase of the high-frequency carrier vary with the instantaneous value of the modulated signal , This modulation is called FM or phase modulation.Audio signal in the domestic television broadcasting is the FM signal in the ultra-high frequency band.Because FM has a series of advantages such as strong anti-interference, small nonlinear distortion, cost-effective launch equipment, So it’s on radio and