| 摘要 |
<p>The instrument has a viewing device rotatable about a horizontal axis. Its light path running in radial direction to the axis, leads to a light detector which generates a signal when the light path points to the light source. The viewer (22) is rotated about the horizontal axis (30) at a speed specified by a motor. A reference device (50, 52, 54) delivers a reference signal when the viewer (22) is at a specified position w.r.t. an artificial horizon (20). An angle measuring unit automatically derives the elevation angle from the speed of rotation and time interval between the reference signal and detector signal. It gives the light source (56) elevation above the artificial horizon.</p> |
