Position determining equipment.

摘要

The position of an object relative to a land vehicle or sea craft is measured using electromagnetic waves transmitted between the object and the land vehicle or sea craft. The object could be a worker on a construction site, and the method could be used to provide a warning when a worker was in a dangerous position relative to the land vehicle; electromagnetic waves of frequency less than 5MHz may be used, and signal strength or phase could be measured. A UHF frequency in the range 2MHz to 1GHZ could be used to transmit from the object to the vehicle or sea craft.