| Popis: |
Velocity determination as one of the widely used spatial information is essential for the location-based services. Concerned researches about Global Navigation Satellite System (GNSS) velocity determination mainly focus on carrier phase observations, which ignored the merits of multi-type observations transmitted by multi-GNSS satellites. To increase the performances of GNSS velocity determination, the Helmert variance components estimation (VCE) algorithm is introduced into the integration of Doppler and carrier phase observations, moreover a velocity vector constraint is designed with the aid of original phase observations, constructing the condition equation, and inserting into GNSS velocity determination model. According to kinematics experiments, results show that the integrated Doppler and carrier phase observations can obtain cm/s level accuracy for E, N and U directions, with improvements of 94.1%, 93.9% and 89.5% respectively, compared with Doppler-only scheme. However, the obvious accuracy reductions are occurred during the satellite signal obstruction, where the corresponding improvements with 89.7%, 90.1% and 69.4% for E, N and U directions can be obtained. Meanwhile, the constraint condition can ameliorate the impacts of signal obstruction, with the improvements of 30.8%, 8.3% and 5.0% for E, N and U directions based on the integration solution. |
