Antenna Phase Wind-up Error Analysis of GNSS Relative Positioning Double-Difference Model

In high-precision global navigation satellite system (GNSS) positioning, phase wind-up is a non-negligible error, which is a rotary error caused by the relative rotation of the right-polarized signal due to the rotation of the receiving antenna and the transmitting antenna. When the antenna is only rotated about its boresight, the short baseline double-difference model can eliminate wind-up, so static short baseline positioning as well as real-time kinematic (RTK) measurement usually ignore this error correction. In order to study on the effect of phase wind-up in double-difference model when rotation direction of the antenna is inconsistent with the boresight (i.e. a wobbling or tumbling occurs), three kinds of antenna attitude changes are designed by using rotating robot. Then two aspects that the wind-up theoretical calculated value by the external antenna attitude information and the residual value of the phase double-difference, are used to prove that the short-baseline relative positioning double-difference model can't completely eliminate the phase wind-up error when the antenna is tilted. When the antenna tilt angle is reached to±50°, the double-difference residual peak-to-peak can be up to 0.03 m. Each satellite double-difference residual root mean square error(RMSE) has decreased by 21%-47% and dynamic short baseline positioning coordinate deviation RMSE by 27%-33% after wind-up correction with attitude information. Finally, the experimental results verify that the phase wind-up effect caused by the antenna tilt in the short baseline relative positioning is approximate equivalent to the phase wind-up effect caused by the earth curvature in the medium and long baseline.