Daily Quality Checks
Routine on-site checks of data and equipment are the best way to quickly identify any performance problems so that erroneous data is not submitted and continuous operation is maintained.
SLR data is checked by long arc and short arc analysis. The long arc involves processing the previous week's Lageos and Etalon data to give station site coordinate residuals so that outlying biases in satellite passes can be identified. Short arc analysis looks at individual passes which were tracked by more than one SLR station simultaneously to compare the station residuals.
The GNSS sites at the SGF, HERS and HERT, track GPS and GLONASS satellites in all directions as they cross the sky down to close to the horizon. Quality check sky plots are checked regularly to ensure the receivers are functioning properly.
The CPF format satellite orbit predictions provided by the SGF, other analysts and mission controllers are compared to quickly identify problems. More detail is in the residual plots of each CPF provider that submits predictions to the ILRS realative to a running average of all available.