Receiver Autonomous Integrity Monitoring (RAIM) is a technique that provides integrity using redundant satellites (i.e. beyond the minimum required to estimate the user position) to protect the user against large navigation errors. It is able to detect and to exclude a faulty measurement based on a self-consistency check of the available observables.
Modern RAIM algorithms combine onboard detection and exclusion techniques with additional integrity information from SBAS or GBAS. An important improvement they can offer is the significantly reduced Time-To-Alert (TTA), which can fulfill the stringent precision approach requirements.
Our current activities in the field of RAIM focus on Advanced RAIM (ARAIM) for the multi-constellation and multi-frequency scenarios, its integration with a proposed Integrity Support Message (ISM) to be broadcast by future navigation systems, as well as carrier phase RAIM (CRAIM) for high precision applications.