GNSS Antenna Phase Centre corrections

For precise GPS positioning and scientific applications it is important to recognize that the antenna phase centers do not represent fixed points with respect to the antenna reference marker (neither at the emitter end or at the receiver end).

The antenna phase center is the point where the receiver detects the signal and on the emitter side where the signal originates, this point actually moves as the geometry changes. The PCV (phase center variation) file has been used up to GPS wk1400 (Nov, 2006) to correct the GNSS measurements, this file specifies the corrections depending on elevation angle for most GNSS receiver antennas. The corrections are specified in relative terms by assuming that the first mass produced geodetic antenna (DORNE MARGOLIN) was giving the ground truth and all the other antennas where calibrated to that model antenna. The satellites were assumed not to have zenith variations and the Phase Center to Center Of Mass vectors where agreed to, according the GPS satellite block:

/* CLK ANT Z-OFFSET (M): II/IIA 1.023; IIR 0.000

Since GPS wk1400 the antenna calibrations have been changed. This effect has recently been calibrated for a very large number of antennas in an absolute sense using most available data from the last few years, and presented in a new international format called ANTEX (ATX). The new absolute calibration has as before L1 and L2 offsets (1st order effects) for all antenna types (receivers and now satellites!), it also contains elevation(zenith) dependent corrections for all antennas (2nd order effect), additionally there are azimuth effects (3rd order effect) for ground antennas since most of them do not have symmetrical correction maps:

Prestige

Happy Positioning!

Ignacio Romero
Director

One Response to “GNSS Antenna Phase Centre corrections”

  1. Soluciones Avanzadas Canarias S.L. » IGS reprocessing an exciting project! Says:

    […] IGS is now using absolute Antenna Phase Center calibrations for ground and space antennas (ANTEX), this has brought the IGS ITRF station position estimations closer to other techniques and reduced […]

Leave a Reply