Clock error, orbit determination accuracy is relatively low about ginan

[seballgeyer]

Hello,

I've reviewed the issues you're experiencing with the orbit accuracy assessment using the pod.yaml file and the sample data. It's clear that the inclusion of satellite G04, which was the first GPS BLK-IIIA SV and not fully operational at the time, has led to large errors.

The status of G04 as unhealth is detrimental to the accuracy of the orbit determination. Its exclusion is necessary to maintain the integrity of the data processing and to ensure the accuracy of the results.

For the backward Kalman data processing, please refer to the _smoothed files for detailed information on the backward smoothed run. To further improve the accuracy of orbit determination through post-processing, you will need to use those file in the comparison scripts.

Additionally, for the comparison script you are using, it would be beneficial to include the -h ECF option to correct a potential offset in the ECF reference frame of the orbits by fitting a Helmert transform. Also, using -n daily -n epoch to compare the clocks will help remove an epoch-wise and a daily offset. Implementing these options should enhance the results.
Your updated command line would be :

orbq -i pod_example_201919900.SP3_smoothed  igs20624.sp3 -h ECF
clkq -i pod_example_201919900.CLK_smoothed  igs20624.clk_30s  -n daily -n epoch

I hope these recommendations will assist you in achieving more accurate orbit determinations. Should you need any more help, please don't hesitate to ask.

Best regards,
Sebastien