| 摘要 |
<p>The bench-mark is used to determine the location of a place on a ground. The bench-mark is concreted or driven in the ground which protects it. It comprises an envelope (12) and a passive oscillating circuit (16, 18) inside the envelope. The circuit has a low self-inductive impedance and may be accurately adjusted to a rated frequency. Particular measurements are provided for adjusting said rated frequency. In order to be found, the bench-mark is detected by a transmitter which allows to determine its location. The bench-mark reacts as a passive oscillating circuit which attenuates the transmitter. The envelope (12) of the bench-mark is sharp, thereby allowing to drive it easily in the ground. </p> |
