Page 260 - Build Your Own Transistor Radios a Hobbyists Guide to High-Performance and Low-Powered Radio Circuits

Amplitude

Input Signal's
Spectrum
W

I Frequency

fs 2fs Зfs
FIGURE 15-48 Spectrum of ап ideally sampled signal.

Amplitude

Input Signal's
Spectrum
W

I Frequency
fs 2fs Зfs
FIGURE 15-4С Spectrum о' ап input signal multiplied or sampled with а
square-wave signal.
In Figures 15-1 through 15-4, examples of sampling аге shown. And generally in а
sampling system, the frequency range of the input signal f in is less than half the

sampling fгeqiuency f s . That is, if f s , the sampling fгeq ие псу, is 96 kHz, then the
maximum frequency of f in is less than 48 kHz. However, in some sampling mixeгs,
the frequency range of f in is above one-half the sampling frequency, and as а

result, aliasing signals occur. Is aliasing necessarily bad? We know that aliasing is
bad in digital audio signal processing when the input frequency violates the Nyquist
sampling rate and causes aliasing distortion signals within the audio band. But