| 摘要 |
<p>Digital signal processing systems for converting a digital signal of a first resolution to a digital signal of a second different resolution include a generator for dither noise. The dither noise is used in such a way as to mask or reduce the effect of non-linearities in the system. The generator generates the dither noise for use in processing a current sample of a lower resolution signal in functional dependence upon previous samples of the lower resolution signal. In one sample, the dither noise generator is formed as a look-up table addressed by the least significant bits of the previous, e.g., 16 samples. The least significant bits of those samples are stored in a buffer. In a digital encoder which encodes a high resolution digital signal to produce a lower resolution signal, the dither noise output from the generator is added to the lower resolution signal at the input to a quantizer. In a complementary digital decoder, the output of a matching dither noise generator is subtracted from the lower resolution digital signal. The encoder and decoder may be combined in a transmission system which transmits a higher resolution signal via a lower resolution digital channel formed, e.g., by a digital storage medium such as a CD, DAT or other digital tape format.</p> |
