| 摘要 |
<p>PURPOSE: To enhance accuracy and reliability in the measurement by detecting the geomagnetic azimuth angle in one arbitrary direction based on the phase angle of a rotating field where the strength of combined field of rotating field and geomagnetic field, detected by means of a field strength sensor, has a maximal or minimal absolute value. CONSTITUTION: X-axis coils 3, 4 and Y-axis coils 1, 2 are arranged symmetricaliy to YZ and XZ planes, respectively, while aligning the central axes with the X-axis and Y-axis. The coils 3, 4 and 1, 2 are connected, respectively, in series and fed with AC currents IX=cosϕand IY=sinϕfrom AC current sources 10, 9 to induce fields HX, HY proportional to the currents IX, IY in the directions of X-axis and Y-axis. Output from a field strength sensor 5 is then fed to a maximal value (minimal value) detector and the phase angleϕof rotating field having maximal value (minimal value), the waveform of the current IX, IY or the instantaneous level of the current is detected by a level detector. Finally, the detection level is subjected to inverse cosine or sine transform thus detecting the azimuth angleϕ(ϕ-180 deg.) of geomagnetism.</p> |
