Editing Delta modulation (section)

== Adaptive delta modulation ==
Adaptive delta modulation (ADM) was first published by Dr. John E. Abate ([[Bell Labs]] Fellow) in his doctoral thesis at [[New Jersey Institute of Technology|NJ Institute Of Technology]] in 1968.<ref>{{cite web |last1=Abate |first1=John Edward |title=Linear and adaptive delta modulation (1967) |url=https://digitalcommons.njit.edu/cgi/viewcontent.cgi?article=2383&context=dissertations |website=Digital commons @ New Jersey Institute of Technology}}</ref> ADM was later selected as the standard for all [[NASA]] communications between mission control and space-craft.

In the mid-1980s, Massachusetts audio company [[Dbx (company)|DBX]] marketed a commercially unsuccessful digital recording system based on adaptive delta modulation. See [[Dbx Model 700 Digital Audio Processor|DBX 700]].

Adaptive delta modulation or [[Continuously variable slope delta modulation]] (CVSD) is a modification of DM in which the step size is not fixed. Rather, when several consecutive bits have the same direction value, the encoder and decoder assume that slope overload is occurring, and the step size becomes progressively larger.

Otherwise, the step size becomes gradually smaller over time. ADM reduces slope error, at the expense of increasing [[quantization error]]. This error can be reduced by using a low-pass filter. ADM provides robust performance in the presence of bit errors meaning error detection and correction are not typically used in an ADM radio design, it is this very useful technique that allows for adaptive-delta-modulation.