1. Energy signal and power signal
1. Energy signal
A signal with limited energy is an energy signal;
2. Power signal
A signal with limited power is a power signal.
In summary, all periodic signals are power signals, and all finite number of pulsed signals are energy signals.
(Reference: The difference between energy signal and power signal )
2. Energy Spectrum and Power Spectrum
1. Energy Spectrum
The energy spectrum is also called the energy spectral density, and the energy spectral density describes how the energy of a signal or time series is distributed with frequency. The energy spectrum is the square of the FFT transformation of the original signal.
2. Power Spectrum
The power spectrum is also called the power spectral density function, or PSD for short. The power spectrum is the signal power within a unit frequency band.
The Wiener-Hinchin theorem proves that the power spectrum of a section of signal = the Fourier transform of the autocorrelation function of this section of signal.
knowledge points
1. Both FFT and PSD can represent the spectral characteristics of a signal. Why do you need to propose PSD when you have FFT?
Signals are divided into definite signals and random signals, definite signals are divided into energy signals and power signals, and random signals must be power signals. The energy signal can be directly transformed by FFT, but the power signal cannot. For signals that cannot be directly subjected to FFT, only autocorrelation can be performed first, and then Fourier, that is, PSD.