Automatic gain controller

A modem with an improved digital signal processor is described. A first processor (l2) controls the overall operation of the modem and communicates with an external device (not shown) through a connector (l0). A second processor (34) performs signal processing on both transmitted and received data signals in a manner which saves both time and memory space. The processes which are described comprise a 240 bit per second handshake signal detector, a fast linear-to-mu lay converter the transmitter signal generator, a fast-acting nonlinear automatic gain control, a jitter-free transmitter phase-locked loop, a baud clock timing recovery circuit, and a phase and amplitude modulator. Also described is a protocol; for exchanging data between the processors (l2) (34). A logic gate array (l5) allows thee processors (l2) (34) to communicate with each other and also performs other functions. Therefore, each of the processors (l2) (34) performs the operations for which it is most suited by its design.