Satellite navigation systems send several signals that are used to decode the satellite's position, distance between the user satellite, and the user's precise time. One signal encodes the satellite's ephemeris data, which is used to accurately calculate the satellite's location at any time. Space weather and other effects causes the orbit to change over time so the ephemeris has to be updated periodically. Other signals send out the time as measured by the satellite's onboard atomic clock. By measuring signal times of arrival (TOAs) from at least four satellites, the user's receiver can re-build an accurate clock signal of its own and allows hyperbolic navigation to be carried out.
satellite navigation systems send several signals that are used to decode the satellite's position distance between the user satellite and the user's precise time one signal encodes the satellite's ephemeris data which is used to accurately calculate the satellite's location at any time space weather and other effects causes the orbit to change over time so the ephemeris has to be updated periodically other signals send out the time as measured by the satellite's onboard atomic clock by measuring signal times of arrival (toas) from at least four satellites the user's receiver can re-build an accurate clock signal of its own and allows hyperbolic navigation to be carried out