| 摘要 |
<p>An apparatus (102) is adapted to detect the linear extensions of a plurality of hydraulic cylinders. Each hydraulic cylinder defines a variable length coaxial resonant cavity. Under the control of a controller (112), a transmitting section (106), a receiving section (110) and multiplexers (306, 307) are used to multiplex RF signals to and from the cavity of each cylinder and to determinethe resonant frequency of the cavity. The controller (112) determines the linear extension of each cylinder as a function of its resonant frequency.</p> |
