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GPS time is expressed with a resolution of 1.5 seconds as a week number and a time of week count (TOW). [13] Its zero point (week 0, TOW 0) is defined to be 1980-01-06T00:00Z. The TOW count is a value ranging from 0 to 403,199 whose meaning is the number of 1.5 second periods elapsed since the beginning of the GPS week.
GPS formerly included a feature called Selective Availability (SA) that added intentional, time varying errors of up to 100 meters (328 ft) to the publicly available navigation signals. This was intended to deny an enemy the use of civilian GPS receivers for precision weapon guidance.
Time to first fix. Time to first fix (TTFF) is a measure of the time required for a GPS navigation device to acquire satellite signals and navigation data, and calculate a position solution (called a fix). An animation depicting the orbits of GPS satellites in medium Earth orbit.
The Global Positioning System (GPS), originally Navstar GPS, [2] is a satellite-based radio navigation system owned by the United States Space Force and operated by Mission Delta 31. [3] It is one of the global navigation satellite systems (GNSS) that provide geolocation and time information to a GPS receiver anywhere on or near the Earth where ...
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] It uses measurements of the phase of the signal's carrier wave in addition to ...
When GPS was first being put into service, the US military was concerned about the possibility of enemy forces using the globally available GPS signals to guide their own weapon systems. Originally, the government thought the "coarse acquisition" (C/A) signal would give only about 100- metre (330 ft ) accuracy, but with improved receiver ...
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. After 1,023, an integer overflow causes the internal value to roll over ...
The pseudorange (from pseudo- and range) is the pseudo distance between a satellite and a navigation satellite receiver (see GNSS positioning calculation), for instance Global Positioning System (GPS) receivers. To determine its position, a satellite navigation receiver will determine the ranges to (at least) four satellites as well as their ...