Realization of power line modem using a direct sequence spread spectrum technique

A power line modem (PLM) which transfers data safely through power lines in houses or small offices is realized in the form of a wall-socket plug. In order to cope with the noisy environment created by uncontrolled AC power lines, a direct sequence (DS) technique is employed. Most of the circuits required for the DS technique are implemented via software programmed inside the system controller, and the complicated synchronized circuit is replaced by a simple circuit using a 60 Hz power signal. The data rate is 60 bps and the PN (pseudonoise) chip rate is 2 kcps. Thus, the process gain of the PLM is about 15 dB