| 摘要 |
PCT No. PCT/NL90/00137 Sec. 371 Date Mar. 11, 1992 Sec. 102(e) Date Mar. 11, 1992 PCT Filed Sep. 20, 1990 PCT Pub. No. WO91/04611 PCT Pub. Date Apr. 4, 1991.System for converting a PCM input signal with uniform noise spectrum, comprising a series of digital words each of K-bits appearing with a predetermined repetition frequency, into an PCM output signal with a non-uniform noise spectrum comprising a series of digital words each of L-bits, L being small than K. The system comprises at least a 1-bit coder embodied to provide a shaped noise profile and to convert the K-L least significant bits of each word from the input signal into a series of 1-bit words, and an accumulator for combining said 1-bit words with the L most significant bits resulting into the desired PCM output signal. The frequency with which said K-L least significant bits of the words of the input signal are converted by said 1-bit coder is equal to said earlier mentioned repetition frequency. |
