User accuracy refers to how close the device's calculated position is from the truth, expressed as a radius. To calculate its position, a GPS device measures its distance (range) from multiple GPS satellites. Please report them to the responsible parties using the links in our Address, Route, and Map Problems section.įor help with GPS problems that are not mapping errors, please visit our GPS Service Outages & Status Reports page. government cannot correct mapping errors in consumer devices. Missing roads, buildings, communities, etc.Mislabeled businesses and other points of interest.In many cases, a device's GPS hardware is working fine, but its mapping software is faulty. Improperly designed devices that do not comply with GPS Interface Specifications.Satellite maintenance/maneuvers creating temporary gaps in coverage.Signals reflected off buildings or walls ("multipath").Satellite signal blockage due to buildings, bridges, trees, etc.Many things can degrade GPS positioning accuracy. Why does GPS sometimes show me in the wrong place? Recent FAA data shows their high quality, single-frequency GPS receivers attaining horizontal accuracy of ≤1.82 m (5.97 ft.), 95% of the time. These can enable real-time positioning within a few centimeters, and long-term measurements at the millimeter level.
High-end users boost GPS accuracy with dual-frequency receivers and/or augmentation systems. However, their accuracy worsens near buildings, bridges, and trees. GPS satellites broadcast their signals in space with a certain accuracy, but what you receive depends on additional factors, including satellite geometry, signal blockage, atmospheric conditions, and receiver design features/quality.įor example, GPS-enabled smartphones are typically accurate to within a 4.9 m (16 ft.) radius under open sky ( view source at ION.org).
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