A differential pulse code modulation system substantially reduces sign redundancy by transmitting a flag signal only when a change in polarity exists between differential samples. Between the flag signals, only the absolute magnitude of the differential samples is transmitted. In another arrangement, an amplitude word is transmitted after a second flag signal which signifies a change in polarity of a differential sample accompanied by a large amplitude level. The amplitude word operates an expanded scale coding mode which assigns a quantized level to the differential sample that is changed in sign.
SIGN REDUNDANCY REDUCTION IN DIFFERENTIAL PULSE MODULATION SYSTEMS