| 摘要 |
<p>A proximity switch for detecting a target in proximity with the proximity switch has wireless transmitter means (3) for transmitting a first pulsed signal (D) having a first carrier frequency (XX) to the target. The proximity switch also has wireless receiver means (6) for receiving a second pulsed signal (H) having a second carrier frequency (YY), different from the first carrier frequency, from the target. The proximity switch further has controller means (8, 9) for providing an output indicative of whether a predetermined correspondence is satisfied between the first and second pulsed signals.</p> |
