| 摘要 |
<p>A ripple control system for an electric power distribution system wherein the receiver has a pair of synchronous filters driven 90.degree. out of phase with each other, the outputs of which are squared and summed to form an output independent of phase, and further discrimination means comprising a microcomputer programmed for frequency checking of each synchronous filter output whereby frequency differences between the synchronous filter centre frequency and the incoming signal frequency are used to give complete rejection characteristics, thus producing a very narrow bandpass filter for the receiver detection system and enabling the use of a large number of closely spaced frequencies for the formation of signalling codes.</p> |
