Dither in Digital Audio Systems

[preliminary version]

Dither is the process of adding noise to a signal before quantization to eleminate all quantization distortion. Drawback of adding dither to the signal is an increased noise level, but quantization distortion can be eliminated completely, which is a significant advantage especially at low signal levels.

Here are some simulated plots of the transfer function for various types and levels of additive dither. As you can see with the right amount of dither the transfer function can be completely linearized. (click on any image to see a larger version)

No Dither nodither.dat.png
1.00 LSB
nodither.dat.png
1.00 LSB
nodither.dat.png
1.00 LSB
Rectangular Dither rec0.25.dat.png
0.25 LSB
rec0.5.dat.png
0.50 LSB
rec1.0.dat.png
1.00 LSB
Triangular Dither tri0.25.dat.png
0.25 LSB
tri0.5.dat.png
0.50 LSB
tri1.0.dat.png
1.00 LSB
Triangular Dither, highpass filtered trihp0.25.dat.png
0.25 LSB
trihp0.5.dat.png
0.50 LSB
trihp1.0.dat.png
1.00 LSB
Gaussian Dither gauss0.5.dat.png
0.50 LSB
gauss1.0.dat.png
1.00 LSB
gauss1.5.dat.png
1.50 LSB


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last modified: 2008-04-26
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