3 results about "Magnetic declination" patented technology

The present disclosure relates to a method for determining a calibrated true north azimuth, a method for laser communication, and a laser alignment system. The calibrated true north azimuth is used for an alignment unit of a laser communication terminal, the laser communication terminal comprising at least a local device and a target device, the method comprising: obtaining coordinate data of the local device and coordinate data of the target device, the coordinate data comprising: longitude, latitude, and altitude; determining a target azimuth and a target elevation of the local device based on the obtained coordinate data of the local device and the coordinate data of the target device; obtaining an alignment date of the local device, so as to determine a true north azimuth corresponding to the target azimuth and corrected by a magnetic declination from a world magnetic field model according to the coordinate data of the local device and the alignment date. The present disclosure can determine a calibrated true north azimuth and perform alignment, thereby improving the alignment accuracy between laser communication devices.

The application provides a magnetic field orientation method and a directional navigation chip with a built-in real-time geomagnetic model. The magnetic field orientation method is applied to the directional navigation chip. The method comprises the following steps: acquiring inertial data output by an inertial sensor and a magnetic field vector output by a magnetic field sensor; acquiring a local real-time geomagnetic reference vector and a magnetic declination angle predicted by a real-time geomagnetic model built in the directional navigation chip; calculating a magnetic field deviation based on the measured magnetic field vector and the local real-time geomagnetic reference vector; judging whether the magnetic field deviation is greater than a deviation threshold; if the magnetic field deviation is not greater than the deviation threshold, calculating an initial attitude angle based on the inertial data and the measured magnetic field vector by using a complementary filtering algorithm; if the magnetic field deviation is greater than the deviation threshold, calculating the initial attitude angle by reducing the weight of the measured magnetic field vector; obtaining a fused attitude angle after attitude fusion calculation based on the initial attitude angle; and calculating a true north azimuth angle based on the fused attitude angle and the magnetic declination angle. The application can directly calculate and output the true north direction by the directional navigation chip.