一般来说，瞬时频率和群延迟在时频平面内定义了两条不同的曲线，但是在时宽（T）和频宽（B）的乘积值逐渐变大时，这两条曲线会慢慢逼近。为了说明这一点，下面计算了信号的瞬时频率和群延迟，T*B值小。- In general, the instantaneous frequency and group delay in the time-frequency plane defines two different curves, but when the width [T] and bandwidth

这是个带通信号仿真调制代码，画出带通信号X(t)的幅度谱，带通信号X(t)的包络波形等。-This is a simulation of bandpass modulation code, and draw the bandpass signal X (t) the amplitude spectrum, bandpass signal X (t) the envelope waveform.

提出一种基于快速傅里叶变换( F F T)提取相位的方法, 分析自混合干涉信号, 不增加系统复杂度就能将激光自混合( SM LD) 微位移测量精度提高到纳米量级。(A phase extraction method based on F F T is proposed. The self mixing interference signal is analyzed, and the accuracy of the self mixing (SM LD) micro displacement me