Quantisation noise discussion - first draft
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=== Sampling and Quantisation Considerations ===
When
The first is the resolution of your conversion - the number of bits you want to represent. The choice here will affect the amount of [https://en.wikipedia.org/wiki/Quantization_(signal_processing) quantisation] noise introduced into your signal. For example, let's assume you have a bipolar input signal that varies between -1V and 1V. With an 8-bit converter, that means that a range of width 2V is represented by values of anything from -127 to 127 (or 255 steps). That means that the input voltage represented by 1 bit of the converted signal is equivalent to 7.84 mV. Assuming a perfectly linear converter, where the quantisation error is uniformly distributed between -1/2 LSB (Least Significant Bit) and 1/2 LSB, this means that when an input signal
For an "ideal" ADC, the signal to quantisation noise ratio (SQNR) is calculated as:
'''SQNR = 20 log<sub>10</sub>(2<sup>Q</sup>)''' dB
where Q is the number of quantisation bits.
[[File:Sampling-illustration.png|frameless|1000x800px]]
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