Delta modulation

The idea of coding the human voice into digital pulses was conceived more than three decades ago; exploitation had to await the ushering in of the transistor era. Since then, coding systems gradually have improved. One of the latest and most efficient schemes is delta modulation. Compared with earlier analog-to-digital-pulse conversion systems, an increase in the voice-handling capacity of telephone equipment by a factor of two or more has been made possible. At the same time, equipment requirements have become less stringent.