| 摘要 |
A signalling system is disclosed, comprising a DC power source, a power drain, a cable interconnecting the source and drain, including at least two cores, a signal generator, and a signal receiver; the signal generator being adapted to modulate the power output of the source in dependence on the signal to be transmitted, the signal receiver comprising a comparator 212 adapted to compare the instantaneous power output of the source at node 216 with a historical average power output at node 214 thereby to detect the signal. Such a system is reliable in an electrically noisy environment, such as an elevator. The historical average power output at node 214 is provided by a compacitor 200 and a diode 206. |
