Chapter 3

Conversion

3.1 Introduction to conversion

The most useful and therefore common signal representation is pulse code modulation or PCM which was introduced in Chapter 1. The input is a continuous-time, continuous-voltage video waveform, and this is converted into a discrete-time, discrete-voltage format by a combination of sampling and quantizing. As these two processes are independent they can be performed in either order. Figure 3.1(a) shows an analog sampler preceding a quantizer, whereas (b) shows an asynchronous quantizer preceding a digital sampler.

Figure 3.1 Since sampling and quantizing are orthogonal, the order in which they are performed is not important. In (a) sampling is performed first and the samples are quantized. This ...

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