Question
What is “dither” with respect to analog-to-digital converters?
Answer Options
- A) An abnormal condition where the converter cannot settle on a value to represent the signal
- B) A small amount of noise added to the input signal to reduce quantization noise
- C) An error caused by irregular quantization step size
- D) A method of decimation by randomly skipping samples
Correct Answer: B
Explanation
When an Analog-to-Digital Converter (\text{ADC}) digitizes a very weak analog signal, the signal may be so small that it falls entirely within a single quantization step, making it invisible to the ADC and creating quantization error. This error is systematic and results in a non-linear digital output for very small inputs.
Dither is a sophisticated technique that involves adding a small amount of noise (usually random noise) to the input signal to reduce quantization noise. This noise causes the weak signal to randomly jump up and down across multiple quantization steps. When the signal is then averaged or filtered in the digital domain, the quantization noise is effectively randomized and spread out, allowing the original weak signal’s information to be successfully recovered.
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