30-08-2017, 01:10 PM
Electrical signals have time and frequency representations. In the time domain, voltage or current is expressed as a function of time, as illustrated in Figure 1. Most people are relatively comfortable with time domain signal representations. Signals measured on an oscilloscope are displayed in the time domain and digital information is often transmitted by a voltage as a function of time.
Signals physically exist in the time domain and are generally expressed as a function of the time1 parameter. Due to this feature, it is not too difficult, at least in most situations of interest to us, to visualize the behavior of the signal in the time domain. In fact, it may even be possible to see the signals on an oscilloscope. But equally important is the characterization of the signals in the frequency domain or spectral domain. That is, we characterize the signal in terms of its different frequency components (or their spectrum). The Fourier analysis (Fourier series and Fourier transform) helps us reach the spectral description of the relevant signals.
Signals physically exist in the time domain and are generally expressed as a function of the time1 parameter. Due to this feature, it is not too difficult, at least in most situations of interest to us, to visualize the behavior of the signal in the time domain. In fact, it may even be possible to see the signals on an oscilloscope. But equally important is the characterization of the signals in the frequency domain or spectral domain. That is, we characterize the signal in terms of its different frequency components (or their spectrum). The Fourier analysis (Fourier series and Fourier transform) helps us reach the spectral description of the relevant signals.