| 摘要 |
<p>A point to multipoint signalling system is provided between a first signalling device and a plurality of second signalling devices. The first signalling device comprises means for receiving signals transmitted from the plurality of second signalling devices, means for modulating the received signals with respective modulation data for the second signalling devices and means for reflecting the modulated signals back to the respective second signalling devices. Each second signalling device comprises means for generating a signal, means for transmitting the generated signal to the first signalling device, means for receiving the modulated signal which is reflected back from the first signalling device and means for retrieving the modulation data from the reflected signal. A retro-reflector and a multipoint to point signalling system are also provided.</p> |
