| 摘要 |
<p>A system for locating a transponder (10) to an accuracy of plus or minus about 10 m in an area about 5 km across includes a master station (12) and two slave stations (14, 16) at known positions. The transponder and the two slaves each incorporates an electronic flywheel circuit and means to bring it into synchronism with a synchronising signal from the master station. After a present delay the transponder then transmits a radio signal to be received by the slave stations and by the master station, the time of receipt of which is measured at each. From these times the location of the transponder (10) is determined by a computer (18).</p> |
