Bandwidth

For analog signals, the bandwidth is the length of the frequency extension, measured in hertz (Hz), in which the greatest signal power is concentrated. It can be calculated from a temporal signal using Fourier analysis. Frequencies that lie between these limits are also called effective frequencies.

Figure 1. The bandwidth is determined by the frequencies between f₁ and f₂.

Thus, the bandwidth of a filter is the difference between the frequencies at which its attenuation when passing through the filter remains equal to or less than 3 dB compared to the peak center frequency (f_c) in Figure 1.

Frequency is the physical magnitude that measures the times per unit of time in which a cycle of a periodic signal is repeated. A periodic signal of a single frequency has a minimum bandwidth. In general, if the periodic signal has components at several frequencies, its bandwidth is greater, and its temporal variation depends on its frequency components.

Generally the term bandwidth is confused with data transmission speed, which is the speed of bits transmitted and is given in bits per second (bps). It is necessary to clarify that the bandwidth does not represent the maximum frequency of the signal, but the range of frequencies in which the greatest power is concentrated.

Normally the signals generated in electronic systems, be it computer data, voices, television signals, etc., are signals that vary in time and are not periodic, but can be characterized as the sum of many periodic signals of different frequencies.