Computer simulation of an automatic adaptive equalizer for real telephone channels and free data format

Following a short introduction to two important principles of adaptive channel equalization, a computer simulation of a complete linear transmission and equalization scheme is presented. The model includes the transmitter, a time-dispersive noise-free channel, and an adaptive receiver based on the minimum mean-square error criterion. The equalization algorithm described in the paper allows the transmission of time-discrete analog data pulses at a speed of 3600 baud or more while following slow time variations of channel characteristics. It is shown how the measured frequency characteristics of real telephone lines can be used in the simulation process. Some examples are given of the convergence time and of the ratio of output signal-to-intersymbol interference noise, both as a function of equalizer length.