相位展开问题(相位的展开不正确)? [英] phase unwrap issue (the unwrapping of the phases is not correcly)?

问题描述

关于阶段的展开，我有一个问题.

I have an issue regard to the unwrapping of phases over time.

我有一个雷达，它监视缓慢的周期性移动的物体.从接收到的信号中，我想了解对象随时间变化的相位.相移时间信号是从FFT中提取的(对于所有FFT，都在同一FFT箱中).这是我得到的结果:

I have a radar which monitors a slow periodic moving object. From the received signal, i want to see the phase of the object over time. The phase-over-time signal is extracted from FFTs (at the same FFT bin for all the FFTs). Here is the result i got:

因为阶段是包装的，所以我需要对阶段进行解包.我对此使用Matlab命令" unwrap ".所以我得到了:

Because the phases are wrapped, so I need to do an unwrapping for the phases. I use the Matlab command "unwrap" to to this. So I got:

问题在红色圆圈处标记.在这里，我希望此时的信号能够被解包.但是不是，原因是:

The issue is marked at the red circle. Here I expect the signal at this time-instant to be unwrapped. However it wasn't, and the reason is:

- From time sample NO. 42 -> 44, the phases take two time samples to being
wrapped, instead of only one (i.e between two consecutive time samples).
Because of this the phase-over-time signal are not unwrapped correctly. 

我也尝试过使用另一种相位展开方法(自适应数值积分)，但是结果与使用Matlab中的" unwrap "命令相同.

I also tried to used another phase-unwrapping method (Adaptive numerical integration), however the result is the same as using "unwrap" command from Matlab.

这是我希望看到的相移时间信号(我手动进行了拆包):

Here is the phase-over-time signal I expected to see (I did the unwrapping manually):

上面提到的问题是什么(它是一个众所周知的问题，还是有它的名字)?当然，这有什么解决方案?

What is the problem mentioned above (Is it a well-known problem or has any name for it)? And of course what is the solution for this?

非常感谢您的帮助！非常感谢.

I would really appreciate any help from you! Thanks alot.

推荐答案

似乎您的输入信号在-pi和pi之间，并且是您想要的在0和2pi之间的输出，所以为什么不这样做呢?只需将2pi添加到负值?这是一个尝试:

It seems that your input signal is between -pi and pi an your desired output between 0 and 2pi, so why dont'you simply add 2pi to the negative values ? Here is a try:

I = s<0;
s(I) = s(I) + 2*pi;

这应该以更简单的方式提供所需的输出.

That should provide the desired output, in a more simpler way.

最好

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