Abstract: At transmission (10) each bit for transmission is coded as a function of its state by producing (12) a particular coding frequency combination, these being divided into two distinct bands spaced one from another and the coding combinations being chosen such that frequencies ranked in the same sequence place in these combinations do not occupy the same frequency band. A signal comprising the coding combination is injected to the network (N,P) and at reception (20), is applied to demodulators (22, 23), each assigned to one respective frequency band, to be correlated with locally generated signals (25, 26) which reproduce the coding combinations with a constant frequency shift, the bit state being determined (24) as a function of the correlation output.

Abstract: A plurality of single-phase energy sensors each having a first input connected to a current converter and a second input connected to voltage converter supply pulses to a calculating device. The number of pulses over time represents the energy detected by the single-phase sensor. The calculating device is based on a microprocessor and comprises accumulators controlled by the pulses delivered by the energy sensors for supplying the active and reactive power measurements sought. In the case of a four-wire network, it is not necessary to use voltage transformers for the interphase network voltages, and the energy sensors supply pulses which represent the active and reactive energy of each phase.