使用适当的图表,解释之间的时域和频域信号表示的区别

when we think of the time domain,we can easily get the change between time and amplitude,so it's our man's favor to recognize the nature,but we can not get the information about the spectrum ,but in fact what we really care about is the spectrum,from the spectrum,we can get the energy distribution and the filter design and many other design is from the frequency domain,but in fact there is a kind of methods can combines both advantage of them,the wavelet.