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If a fast time to first fix (TTFF) is needed, it is possible to upload a valid ephemeris to a receiver, and in addition to setting the time, a position fix can be obtained in under ten seconds. It is feasible to put such ephemeris data on the web so it can be loaded into mobile GPS devices. [6] See also Assisted GPS.
The GPS week number rollover is a phenomenon that happens every 1,024 weeks, which is about 19.6 years. The Global Positioning System (GPS) broadcasts a date, including a week number counter that is stored in only ten binary digits , whose range is therefore 0–1,023.
It must acquire each satellite signal and obtain that satellite's detailed orbital information, called ephemeris data. Each satellite broadcasts its ephemeris data every 30 seconds with validity of up to 4 hours. Hot or standby The receiver has valid time, position, almanac, and ephemeris data, enabling a rapid acquisition of satellite signals.
The GPS date and time, and the satellite's status. The ephemeris: precise orbital information for the transmitting satellite. The almanac: status and low-resolution orbital information for every satellite. An ephemeris is valid for only four hours, while an almanac is valid–with little dilution of precision–for up to two weeks. [7]
DGPS Reference Station (choke ring antenna)A reference station calculates differential corrections for its own location and time. Users may be up to 200 nautical miles (370 km) from the station, however, and some of the compensated errors vary with space: specifically, satellite ephemeris errors and those introduced by ionospheric and tropospheric distortions.
The Global Positioning System (GPS) is the American satellite-based system for positioning and navigation. Receivers on or near the Earth's surface can determine their locations based on signals received from any four or more of the satellites in the network.
HDOP AND GPS HORIZONTAL POSITION ERRORS; Article on DOP and Trimble's program: Determining Local GPS Satellite Geometry Effects On Position Accuracy. Notes & GIF image on manually calculating GDOP: Geographer's Craft; GPS Errors & Estimating Your Receiver's Accuracy: Sam Wormley's GPS Accuracy Web Page
A surveyor uses a GNSS receiver with an RTK solution to accurately locate a parking stripe for a topographic survey. Real-time kinematic positioning (RTK) is the application of surveying to correct for common errors in current satellite navigation (GNSS) systems. [1]