SYSTEM AND METHOD FOR MEASURING ROUND TRIP DELAY IN A SATELLITE COMMUNICATION SYSTEM

摘要

A system and method for determining a round trip delay of signals transmitted between first and second objects, such as a satellite (104) and a mobile telephone (108), that move relative to each other. A first signal is transmitted (404) from the first object (104, 108) to the second object (108, 104). The first signal is received at the second object (408) after a propagation delay D1, the delay D1 being the time taken by the first signal to traverse from the first object to the second object. A frequency of the first signal is measured (412) at the second object. The second object then transmits to the first object a second signal (416) containing a report of the measured first frequency. The second signal is received at the first object after a propagation delay D2, D2 being the time taken by the second signal to traverse from the second object to the first object. The first object measures a frequency of the second signal (424). The first object then determines the range between the first and second object (428) from the measured overall delay and the measured frequencies of the first and second signals.