An integrated GPS/INS navigation system can employ inertial velocity information to
produce a more robust system. For a stand-alone GPS receiver, decreasing the receiver
tracking loop bandwidth reduces the probability of losing lock in a jamming or interference
environment if vehicle dynamics are low. However, reduced bandwidth increases tracking
errors when dynamics are present. Beyond a certain limit, it causes a serious degradation in
the dynamic tracking loop performance. Providing inertial velocity aiding to the receiver
tracking loops is an effective and popular treatment to help resolve this problem. In this
paper, performance of the GPS receiver tracking loops using inertial velocity aiding will be
investigated. Different types of tracking loops, from 1st to 3rd order, are covered. Following
the discussion of the system architecture and derivation of the related transfer functions for
the tracking loops, both with and without aiding, the system performance, including
transient response, steady-state error, and noise bandwidth is evaluated.
GPS receiver performance characterization under realistic ionospheric phase scintillation environments
