Possibility to use PhaseIonosphericDelayModifier for OneWayGNSSPhase instead of Phase

Dear all,
is it possible to use in some way the PhaseIonosphericDelayModifier for OneWayGNSSPhase instead of Phase?

Many thanks.

Best Regards.

Hi @fpan

To answer your question, we shall talk about three important points:

  • Theoritically, inter-satellite ionospheric effect exists and shall be taken into account in the measurement model.

  • From an Orekit point of view, that’s not possible with the current version of the library. We don’t have that class in the library, but we shall have it!
    However, I don’t know if the current ionospheric models available in Orekit are compatible with inter-satellites ionospheric effect computation. In other words, I don’t know if the Klobuchar model, and its coefficients,can be used for inter-satellite links or if it is only suitable for ground ↔ satellite links.

  • Finally, in terms of architecture, the only thing to do is to implement a new class named OneWayGnssPhaseIonosphericDelayModifier and which implements EstimationModifier<OneWayGNSSPhase>

Best regards,
Bryan

One of the problems we have to solve for inter-satellites ionospheric corrections is to compute the total electronic content when the signal path just traverses a few ionospheric layers (and in fact traverses them probably twice as both the transmitter and receiver may be above the layers), but not all layers.
This is the reason why in InterSatDirectViewDetector we introduced a withSkimmingAltitude configuration, so when generating simulated measurements we can avoid ionosphere. We agree it is akin to sweep the problem under the rug.

Dear Bryan and dear Luc,
many thanks for your replies.

When do you expect that the OneWayGnssPhaseIonosphericDelayModifier will be a feature of Orekit?

Many thanks.

Best Regards

No idea :worried:
This is something I would need too as I am involved in some GNSS with inter-satellite measurements (see ISL : improving GNSS navigation message performance).
I however have no schedule for that yet

Is there a way in Orekit to estimate the ionospheric delay during orbit determination of a LEO satellite?

Many thanks.

No, not specifically ionospheric delay.
You can estimate a bias, but I guess this would include many effects at once.

You can estimate the vertical electronic content using class EstimatedIonosphericDelay which is (I think) the closest Orekit has to estimate the ionospheric delay