A robust system for digital data transmission over the low voltage network using spread spectrum techniques

Digital data transmission over the low voltage network seems promising for many reasons. Because transmission lines are already present, initial costs are low. Furthermore, any load attached to the power circuit can be reached through it. Therefore, a high level of load management, the introduction of complex tariff structures, remote (gas-, water- and electricity)-meter reading, remote disconnection of nonpayers and even primitive telecommunications functions become possible with communications systems able to communicate over the power distribution network. Data transmission over the low voltage network, however, is not straightforward; the low voltage network as a communications channel exhibits a very high signal attenuation (/spl ap/100 dB/km) and strong non-Gaussian noise. Furthermore, strict regulations exist, defining frequency bands and maximum transmitter power that are to be used. In this paper, after an overview of the existing regulations, an analysis of the characteristics of the low voltage network is given. Channel noise and channel attenuation are considered, leading to a proposal for a system using a combination of direct sequence spread spectrum (DSSS) and a kind of frequency hopping spread spectrum (FHSS)-modulation. Because the power line frequency can be used for synchronization, system costs can be kept within acceptable limits.