delta modulation (DM)
Delta modulation( DM) is a type of differential pulse code modulation( DPCM) which differs in that the adjacent samples can only differ from the real sample by the values +1 or -1.
This means that only one bit is used to encode adjacent samples. Fast and high signal changescan be captured by increasing the sampling rate. However, a good speech quality requires a bit rate of more than 200 kbit/s. If the step height is adapted to the signal to be sampled, delta modulation becomes adaptive delta modulation( ADM).
Among other things, delta modulation is used in the sigma-delta converter.