enhHighAenderror

EnhHighAenderror, also known as Enhanced High Altitude Error, is a phenomenon observed in Global Navigation Satellite Systems (GNSS) such as GPS, GLONASS, and Galileo. It refers to an increased error in position, velocity, and time (PVT) measurements when a receiver is operating at high altitudes, typically above 5,000 meters (16,400 feet). This error is not due to a failure in the satellite signals or the receiver hardware, but rather a result of the satellite geometry and the atmospheric conditions at high altitudes.

The primary cause of EnhHighAenderror is the reduced number of satellites visible to the receiver at high altitudes. As the receiver ascends, the number of satellites above the horizon decreases, leading to a less favorable satellite geometry. This poor geometry results in a dilution of precision (DOP), which is a measure of the accuracy of the PVT solution. A higher DOP value indicates a less accurate solution.

Additionally, the ionosphere, which is a layer of the Earth's atmosphere containing free electrons, can cause errors in GNSS signals. At high altitudes, the ionosphere is less dense, but the signals still experience delays due to the free electrons. This ionospheric delay can contribute to the overall error in the PVT solution.

To mitigate EnhHighAenderror, GNSS receivers can use various techniques such as differential correction, which involves using a reference station to correct the errors in the PVT solution, and multi-constellation reception, which involves using signals from multiple GNSS systems to improve the satellite geometry. However, these techniques may not completely eliminate the error, and the accuracy of the PVT solution may still be reduced at high altitudes.