DGPS Kinematic Carrier Phase Signal Simulation Analysis for Precise Velocity and Position Determination

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Abstract
This paper describes the differential GPS and signal simulator equipment, procedures, and simulated aircraft trajectories used to analyze carrier phase measurements in estimating velocities and 3D positions. A differential GPS simulator system was used to generate C/A-code, P-code, and carrier phase signals from segments of the actual GPS constellation. Two pairs of dual-frequency receivers from different manufacturers were tested. These units have the capability of tracking the P-code (L1/L2 for one of the receivers and L2 for the other). An aircraft trajectory with accelerations up to 5 g was simulated, and analysis is performed in terms of the resulting velocity errors and dynamics. Two methods for estimating the 3D velocities were tested, namely carrier phase with fixed-integer and real-number (float) ambiguities. Both raw Doppler measurements and a number of carrier-phase-derived Doppler measurements were tested. As a by-product, the 3D positions could also be determined using various carrier phase approaches. The estimated quantities were compared with the reference quantities known a priori to determine the performance of the receivers under the various conditions simulated.