| 摘要 |
<p>A data reduction system is disclosed which includes an analog to digital converter for converting an analog signal to digital sample signal form, a digital compression filter for compression filtering the digital sample signals, and an encoder for truncated Huffman encoding the compression filter output. A decoder for decoding the encoded signal, a digital reconstruction filter for decompression filtering of the decoded signal, and digital to analog converter means are included to reconstruct the analog signal. The digital compression filter has a transfer function which includes zeros on the unit circle in the Z-plane at substantially zero degrees from the origin, while the digital reconstruction filter has poles on or inside the unit circle in the Z-plane at substantially zero degrees from the origin. The transfer function of the digital compression may also include zeros on the unit circle in the Z-plane at at least one of the following pairs of angles, +41.41, +60.degree., +90.degree., +120.degree. and +180.degree., in which case the transfer function of the digital reconstruction filter includes poles on or inside the unit circle at corresponding angular positions. The poles of the reconstruction filter may be momentarily movable inwardly inside the unit circle in response to a detected error signal to speed recovery from such error signal.</p> |
