Chris Hornbeck wrote:
On Dither
by Mithat Konar

(6) The results in (4) and (5) will not happen by adding noise after the
A/D conversion. Go back to our first experiment and add the random
signal to the output of the ADC. As long as the input signal is between
-0.5 and 0.5 volt, the ADC's average output will still be zero. Between
0.5 and 1.5 volts the average will jump to 1. There is no resolution
enhancement and the quantization effects remain.

I'm probably just reading this wrong, but on it's face, this is
incorrect. Digital dither is used all the time.

Dither is used when reducing the resolution of the signal. It is
effective only when it is applied before the resolution is reduced, not
after. His example uses an imaginary ADC as its basis, but it would be
equally valid if he were talking about reducing word length in the
digital domain.

So, yes, I think you _are_ reading this wrong. His only point is that
dither is NOT effective if it is applied after the resolution has been
reduced (ie, after truncation).

The process of digitizing an analog signal is a process in which
resolution is reduced. So dither is required there, just as it is when
reducing the bit depth of a digital signal. The basic principle is
exactly the same in either case.