receiver autonomous integrity monitoring (GPS) (RAIM)

Receiver Autonomous Integrity Monitoring (RAIM) is a technology used to assess the accuracy of navigation equipment readings. There are various applications, such as civil aviation, that place stringent requirements on the precision, accuracy and availability of global navigation systems. One of the most important requirements is directed towards the integrity of the measurements, since erroneous and inaccurate measurements directly affect safety. This integrity can be ensured by RAIM technology.

RAIM technology uses information from Global Navigation Satellite Systems( GNSS) only; the results can be directly incorporated into navigation equipment for air or marine traffic, or into alternative navigation systems such as the SBAS system or the ABAS system.

To eliminate erroneous measurements caused by faulty navigation satellites or incorrectly received satellite signals, the RAIM system works with as many navigation satellites as possible. Four correctly received navigation signals are required for unambiguous location determination. This means that if one satellite signal from four satellites is faulty, the measurement is faulty. Only when five satellite signals are received can it be determined whether the signal from one satellite was measured incorrectly. The error is detected: Fault Detection( FD). The exclusion of an error - Fault Detection and Exclusion( FDE) - is only possible when six satellite signals are received.