Dear all,
I would ask you a clarification on how to apply the OnBoardAntennaOneWayGNSSPhaseModifier to ionosphere-free combined phase measurements that I saved as OneWayGNSSPhase.
My question is, if now the OneWayGNSSPhase contains the iono-free combined phase and we have therefore a combined frequency, in order to apply the OnBoardAntennaOneWayGNSSPhaseModifier to these iono-free combined measurements should I apply two modifiers for each combined phase, i.e. one for each frequency involved in the iono-free combination?
Are these two modifiers then applied correctly to the combined measurement? Or how should I apply OnBoardAntennaOneWayGNSSPhaseModifier to ionosphere-free combined measurements?
I asked a specialist and he confirmed what I guessed: you start from the 3D vector defining the center of phase for each frequency, and then you create a new vector by computing the iono-free combination expression for each coordinate, i.e. for the X coordinate you would end up with X_{\mathrm{iono-free}} = \frac{f_1^2 X_1 - f_2^2 X_2}{f_1^2 -f_2^2} and similar formulas for Y and Z.
Yes, use OnBoardAntennaOneWayGNSSPhaseModifier.
Basically, the iono-free combination is a linear interpolation between points, so it applies to distances, to phase center coordinates, and to cycles since they are simply distances divided by wavelength. You don’t need to do the division, it is already done internally (see method modifyWithoutDerivatives in OnBoardAntennaOneWayGNSSPhaseModifier.