The performance of an Ultra-Tightly Coupled (UTC) Global Positioning System/Inertial Navigation System (GPS/INS) is evaluated using a system simulation of the GPS receiver and navigation processing. The UTC system being analyzed uses a bank of pre-filters to estimate code delay error and Doppler frequency error for each satellite. These outputs are sent to a central Kalman navigation filter. This central processor generates estimates of inertial navigation position, velocity, and attitude errors; IMU biases; and user clock errors, which are used to correct the navigation solution. In the UTC approach, outputs from the central navigation processor, after projection into satellite line-of-sight coordinates, are used to control the code and carrier replica signals for each satellite channel. In contrast, a conventional tightly coupled GPS/INS system uses separate tracking loops for each satellite channel, which operate autonomously. As a result, the UTC design is considered more robust to jamming and vehicle dynamics. Closed-loop UTC navigation performance is evaluated over a realistic precision guided munition (PGM) scenario in the presence of broadband jamming directed against the GPS system. A realistic IMU error model is assumed, and UTC performance is evaluated over a range of jamming levels. Some preliminary conclusions are then formed about the effectiveness of the UTC approach.
[1]
Per Enge,et al.
Fundamentals Of Signal Tracking Theory
,
1996
.
[2]
センノット,ジェイムス・ダブリュ,et al.
Navigation receiver with coupled signal-tracking channels
,
1993
.
[3]
Donald E. Gustafson,et al.
A deeply integrated adaptive GPS-based navigator with extended range code tracking
,
2000,
IEEE 2000. Position Location and Navigation Symposium (Cat. No.00CH37062).
[4]
Phillip W. Ward.
Using a GPS Receiver Monte Carlo Simulator to Predict RF Interference Performance
,
1997
.
[5]
J.F. Raquet,et al.
Multipath-adaptive GPS/INS receiver
,
2005,
IEEE Transactions on Aerospace and Electronic Systems.
[6]
P. Ward,et al.
Satellite Signal Acquisition , Tracking , and Data Demodulation
,
2006
.
[7]
Ernest J. Ohlmeyer,et al.
Assesment of integrated GPS/INS for the EX-171 Extended Range Guided Munition
,
1998
.