如何将频谱密度转换为幅度 [英] How to convert spectral density to amplitude

问题描述

我有从R"stats"包中的频谱函数调用生成的标准周期图.它在Y轴上产生光谱密度.我希望实际检查关键频率信号的幅度.

I have standard periodogram produced from the spectrum function call in the R "stats" package. It produces a spectral density on the Y axis. I wish to actually inspect the amplitude of the key frequency signals.

我如何将频谱密度转换为振幅? R中是否存在可自动生成频率与幅度图的周期图图/分析?感谢任何建议.

How do i convert the spectral density to an amplitude? Is there a periodgram plot/analysis in R that produces a frequency vs amplitude plot automatically? Appreciate any advice.

推荐答案

也许您使用的术语与我使用的术语不同.帮助页面说，从Spectrum函数返回的值是一个列表，其前两个元素是:

Maybe you use different terminology than I do. The help page says that value returned from the spectrum function is a list whose first two elements are:

freq    
vector of frequencies at which the spectral density is estimated. 
(Possibly approximate Fourier frequencies.) The units are the reciprocal 
of cycles per unit time (and not per observation spacing): see ‘Details’

spec    
Vector (for univariate series) or matrix (for multivariate series) of 
estimates of the spectral density at frequencies corresponding to freq.

$spec元素就是您所说的振幅"矢量吗? (您没有说关键频率信号"是什么，所以我只是从?spectrum中的示例中选择了第四个频率:

So is the $spec element what you are calling the vector of "amplitudes"? (You haven't said what the "key frequency signals" are so I just picked the fourth frequency from the example in ?spectrum:

 lh.spec <- spectrum(lh)

 lh.spec$freq[4]
#1] 0.08333333
  lh.spec$spec[4]
#[1] 1.167519

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