Accumulation of distortion possibly resulting from multiple digital code conversions is prevented by including in an ADPCM-to-PCM decoder (100, FIG. 1 or 600, FIG. 6) an arrangement (119, FIG. 1 or 601, FIG. 6) for making a trial transmission of the resulting PCM sample (.PSI.(k)) to obtain (via 209,...http://www.google.com.tw/patents/US4475213?utm_source=gb-gplus-share專利 US4475213 - Digital code converter
