Spectrum (频谱): This refers to the range of frequencies that a signal contains. In signal processing, the spectrum of a signal or sound provides a representation of which frequencies are present in the signal. In other words, it’s a breakdown of a signal into its frequency components.
Wavelength (波长): This is the spatial period of a wave, the distance over which the wave’s shape repeats. It is usually determined by considering the distance between consecutive points of the same phase, such as crests, troughs, or zero crossings, in a waveform. The standard unit for wavelength is the meter (m).
v=f⋅λ
v: speed
f: freq
λ: wavelength
Energy Signal (能量信号)
Energy of a signal: area under the squared magnitude of the signal
Finite energy (non-zero)
Finite duration
Zero average power
Power Signal (功率信号)
Power of a signal: average of the squared magnitude in the time domain