前言低频与超低频正弦波,通常是用模拟方法产生的。模拟法产生正弦波的类型很多,一般都是由阻容元件组成反馈移相网络而形成的各种型式的振荡器;还有一种可产生多种波形的函数发生器,它先由恒流源对电容器充放电产生三角波,然后再经非线性网络变换为正弦波。如所周知,用模拟法产生的正弦波振荡,其频率精确度不高。目前已出现一种带有小型频率计的数字显示的振荡器,但它仅起频率监测作 Preface Low frequency and ultra-low frequency sine wave, usually generated by analog methods. There are many types of sine wave generated by the analog method, which are generally formed by the RC element consisting of feedback phase shift network and a variety of oscillator can generate a variety of waveforms, which first by the constant current source Charge and discharge capacitors to generate triangular wave, and then by the nonlinear network into a sine wave. As we all know, the sine wave oscillation generated by analog method, its frequency accuracy is not high. A digital display oscillator with a small frequency counter has appeared, but it only functions as a frequency monitor