JPS57176848A - Transmitting system in power line carrier - Google Patents

Abstract

PURPOSE:To remove influences of noises synchronous to the power source, by setting each phase span corresponding to the cycle of the supply voltage to 1 bit, by sending data in 2 bits corresponding to 1 bit of data, and taking the difference in pulse numbers of corresponding phase spans as the reception. CONSTITUTION:When data transmission is performed by receiving carriers with interior distribution lines synchronously to the power source frequency, noises synchronous to the power source frequency occur Fig. (b), and, when the noises are level-detected through a filter tuned to the carrier Fig. (c), noises as shown in Fig. (d) are outputted. In this case, signals 10 and 01 are put on the 1st and 3rd half-cycles and the 2nd and 4th half-cycles of the continuous two cycles of the power source frequency, respectively, and the signals are transmitted corresponding to data 1 and 0 Fig. (e). When the difference between accumulated carrier count numbers of each corresponding half-cycle is larger than a set value at the time of reception, they are decided as signals, and, when the difference is smaller, they are decided as noises. When the 3rd half-cycle is subtracted from the 1st half-cycle of Fig. (e), it becomes Fig. (f) and shows data 1, and when the 4th half-cycle is subtracted from the 2nd half-cycle, it becomes Fig. (g) which shows negative values and shows data 0, and thus, influence of noises are removed.