Quantization Noise & Dither

The Music Telegraph | Text 2019/02/21 [13:46]

Quantization Noise & Dither

The Music Telegraph| 입력 : 2019/02/21 [13:46]

▲ The simplest way to quantize a signal is to choose the digital amplitude value closest to the original analog amplitude. This example shows the original analog signal (green), the quantized signal (black dots), the signal reconstructed from the quantized signal (yellow) and the difference between the original signal and the reconstructed signal (red). The difference between the original signal and the reconstructed signal is the quantization error and, in this simple quantization scheme, is a deterministic function of the input signal.   

© Wikipedia

 



 

Quantization Noise (Error) & Dither

 

 

Quantization Noise

- Least Significant Bit (LSB) (e.g. 0101 111(1))

- If every bit is used, error is not heard

- Error is limited to 1/2 LSB in level

- When level is lowered, you hear more distortion (because sound is calculated logarithmic value)

 

 

Solution: “Dither

- Trade off ‘Noise’ for distortion

- Noise added to a signal before quantizing, so that errors are randomized

- Quantization error is correlated to the signal

- Dither ==> de-correlates that distortion

*Bonus: We hear beneath the Noise Floor

 

Algorithms:

‘Noise Shaping’ - White noise is filtered away from frequency sensitive areas

 

 

 

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