Digital Signal Processing 101

CHAPTER 4Frequency Response

When we have a sampled digital signal, we are ready to perform digital signal processing on this signal. In the preceding chapter, we briefly touched on representing the signal in the frequency domain. Usually, our goal is to modify the signal’s frequency representation. This is normally performed using a filtering function. This is probably the most fundamental of DSP functions. In the previous example of the telephone system, we talked about sampling the voice signal at 8 kHz. Let’s say we want to build an automated system to detect touch tones (on a touch-tone phone, whenever you press a number key, the phone creates two specific tones or frequencies in the audio signal band; i.e., what you hear when pressing the ...