Audio Engineering

Representation of Audio Signals 487

Unfortunately, it is also quite a problem to design accurate and stable quantizers. The
problems include linearity, missing codes, differential nonlinearity, and nonmonotonicity.
Missing codes should be properly considered a fault since they arise when a converter
either does not produce or respond to the relevant code. A suitable test is a simple ramp.

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Figure 15.27(b) : The quantizer maps the noisy signal onto one of a range of unique
levels as before.
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Figure 15.27(c) : The resulting quantizing noise can be compared with the original signal
and this time you can see that the noise waveform has lost the highly structured relationship
shown in Figure 15.26.