GPS code phase variations (CPV) for GNSS receiver antennas and their effect on geodetic parameters and ambiguity resolution

Precise navigation and geodetic coordinate determination rely on accurate GNSS signal reception. Thus, the receiver antenna properties play a crucial role in the GNSS error budget. For carrier phase observations, a spherical radiation pattern represents an ideal receiver antenna behaviour. Deviations are known as phase centre corrections. Due to synergy of carrier and code phase, similar effects on the code exist named code phase variations (CPV). They are mainly attributed to electromagnetic interactions of several active and passive elements of the receiver antenna. Consequently, a calibration and estimation strategy is necessary to determine the shape and magnitudes of the CPV. Such a concept was proposed, implemented and tested at the Institut für Erdmessung. The applied methodology and the obtained results are reported and discussed in this paper.We show that the azimuthal and elevation-dependent CPV can reach maximum magnitudes of 0.2–0.3m for geodetic antennas and up to maximum values of 1.8m for small navigation antennas. The obtained values are validated by dedicated tests in the observation and coordinate domain. As a result, CPV are identified to be antenna- related properties that are independent from location and time of calibration. Even for geodetic antennas when forming linear combinations the CPV effect can be amplified to values of 0.4–0.6 m. Thus, a significant fractional of theMelbourne–Wübbena linear combination. A case study highlights that incorrect ambiguity resolution can occur due to neglecting CPV corrections. The impact on the coordinates whichmay reach up to the dmlevel is illustrated. The final publication is available at Springer via https://doi.org/10.1007/s00190-016-0984-8

Analysis of Galileo IOV + FOC signals and E5 RTK performance

The current Galileo constellation in April 2017 comprises both in-orbit validation and full operational capability satellites transmitting signals on five frequencies, i.e., E1, E5a, E5b, E5, and E6. We analyze the power, multipath and noise of these signals using the data collected by four short baselines of various lengths and receiver/antenna types in Perth, Australia, as well as the Netherlands. In our analysis, the Galileo signals, except E5, show different relative noise and multipath performance for different receiver/antenna types. The E5 signal, with a weak dependency on the type of receiver/antenna, shows a significantly lower level of multipath and noise with respect to the other signals. Estimations of the E5 code standard deviation based on the data of each of the mentioned baselines gives a value of about 6 cm, which is further reduced to about 1 cm once the data are corrected for multipath. Due to the superior stochastic properties of E5 signal compared to the other Galileo signals, we further analyze the short-baseline real-time kinematic performance of the Galileo standalone E5 observations. Our findings confirm that the Galileo E5 data, if corrected for the multipath effect, can make (almost) instantaneous ambiguity resolution feasible already based on the current constellation