| 摘要 |
PURPOSE: To obtain a tracking system using a GPS satellite which can obtain a position, a speed and time information of a moving body such as vehicles or the like correctly. CONSTITUTION: The tracking system comprises a sensor 20 set to each object to be tracked, a communications link 30, a work station 40 and a GPS reference receiver 60. Position accuracy of the sensor is updated at any time by the work station via the communications link 30. The sensor continuously measures through a visible GPS satellite a pseudo area and a delta area, or a time difference, and a frequency error. Unprocessed measured values from the satellite are, together with a related timing and state information, supplied to the communications link 30 and returned to the work station 40 cyclically. The error is corrected at the work station, so that determination accuracy for a position of the object is improved. Although measurements at three points by the satellite are required in general to calculate the position of the object, measurements at least at two points will do in a short period if time, altitude and map-assisting information are fed to the work station. |
