When a digital audio signal is transmitted to a device with a lower quantization (*see entry), dithering combines some of the rounded-off portion with the data that is retained (i.e., instead of simply discarding the lower-value bits), in order to reduce the noise that is generated by this conversion. Since this changes the data itself, there are situations in which it is better not to apply dithering.
The introduction of digital noise. This is the process the DoD uses to add inaccuracy to GPS signals to induce Selective Availability.
An introduction of digital noise. The Department of Defense's process to add inaccuracy to GPS signals to induce Selective Availability.
Dithering is a common technique to improve digitizing when quantization noise ( see also Quantization Error/Noise) can no longer be treated as random. This happens when an analog input signal remains at the same value for many consecutive samples, causing the digitized output to look "stuck" at a certain digital output code even when the input is changing by less than ±0.5LSB. The quantization noise now looks more like a threshold or a distortion rather than additive random noise. To get around this effect, a small amount of random noise is added to the analog input signal. This added noise causes the digital output to randomly toggle between two adjacent codes, thereby avoiding the previously described thresholding effect.
The technique of adding controlled amounts of noise to a signal to improve overall system loop control, or to smear quantizing error in an A/D convertor application.