GNSS Reliability Testing in Signal-Degraded Scenario

Abstract EN

Multiconstellation satellite navigation is critical in signal-degraded environments where signals are strongly corrupted.

In this case, the use of a single GNSS system does not guarantee an accurate and continuous positioning.

A possible approach to solve this problem is the use of multiconstellation receivers that provide additional measurements and allows robust reliability testing; in this work, a GPS/GLONASS combination is considered.

In urban scenario, a modification of the classical RAIM technique is necessary taking into account frequent multiple blunders.

The FDE schemes analysed are the “Observation Subset Testing,” “Forward-Backward Method,” and “Danish Method”; they are obtained by combining different basic statistical tests.

The considered FDE methods are modified to optimize their behaviour in urban scenario.

Specifically a preliminary check is implemented to screen out bad geometries.

Moreover, a large blunder could cause multiple test failures; hence, a separability index is implemented to avoid the incorrect exclusion of blunder-free measurements.

Testing the RAIM algorithms of GPS/GLONASS combination to verify the benefits relative to GPS only case is a main target of this work too.

The performance of these methods is compared in terms of RMS and maximum error for the horizontal and vertical components of position and velocity.