| 摘要 |
<p>A signal transmission system for communicating over the power supply wiring of a building is disclosed. The system includes transmission apparatus (15, 16, 17, 18, 21) which is operable to transmit data by superimposing data pulses on the power supply voltages and a receiving apparatus (11, 12, 13, 14, 21) which is operable to count the data pulses so as to derive the transmitted data. The transmission apparatus is operable to transmit a digital value (1,0) by sending different numbers of pulses in a first transmission interval (1;2), and a subsequent transmission interval (3;4), respectively, and the receiving apparatus includes a noise reduction circuit (14) which is operable to determine the difference between the numbers of pulses (A, C; B, D) received during said first and subsequent transmission intervals and to treat the pulses as representing data only if the difference (1A-C1; 1B-D1) exceeds a predetermined value.</p> |
