Receiver autonomous integrity monitoring

Receiver autonomous integrity monitoring (RAIM) is a technology developed to assess the integrity of individual signals collected and integrated by the receiver units employed in a <a href="/facts/Global_Navigation_Satellite_System/lVgPlF5v">Global Navigation Satellite System</a> (GNSS). The integrity of received signals and resulting correctness and precision of derived receiver location are of special importance in <a href="/facts/Life-critical_system/vhVc7NJU">safety-critical</a> GNSS applications, such as in aviation or marine <a href="/facts/Navigation/sGGAJ0AQ">navigation</a>.
The <a href="/facts/Global_Positioning_System/DKVLnzF3">Global Positioning System</a> (GPS) does not include any internal information about the integrity of its signals. It is possible for a GPS satellite to broadcast slightly incorrect information that will cause navigation information to be incorrect, but there is no way for the receiver to determine this using the standard techniques. RAIM uses redundant signals to produce several GPS <a href="/facts/Fix_(position)/yY41HfWV">position fixes</a> and compare them, and a statistical function determines whether or not a fault can be associated with any of the signals. RAIM is considered available if 24 GPS satellites or more are operative. If the number of GPS satellites is 23 or fewer, RAIM availability must be checked using approved ground-based prediction software.
Several GPS-related systems also provide integrity signals separate from GPS. Among these is the <a href="/facts/WAAS/DghMfANs">WAAS</a> system, which uses separate signals broadcast from different satellites to indicate these problems directly.

Receiver autonomous integrity monitoring open-in-new

Receiver autonomous integrity monitoring