Changes to the Generation of the ILRS Monthly Station Performance Report Cards

The ILRS has been generating "report cards" evaluating network performance on a quarterly basis since 1997 and a monthly basis since 2012. Some assumptions made which were integrated into the initial software that created reports prior to 2020 are no longer valid due to operational and technical improvements in the network, such as an increase in the number of targets, different ways in which stations track, and pass interleaving.

Therefore, new software has been developed by CDDIS, reviewed within the ILRS Central Bureau, and implemented for report cards summarizing data from 2020 onward. These revised report cards address additional needs of the community and correct assumptions made in the original software.

Information and Changes to Table 1

The calculation for passes remains the same; a pass is counted for each satellite's orbit where data is taken by the station.

Item Handling Prior to 2020 2020 Onward
Grouping of LARES in pass and normal point counts Grouped with LEO Grouped with LAGEOS
Duplicate Pass Identification The software looks at each individual item in the header records to determine if it's a new pass-segment and all duplicates were not caught. The software determines is a pass or pass-segment is unique based on whether it's from the same station, satellite, and wavelength and if the start and end time of flight (first and last 11 records) overlap
Pass RMS Calculation Pass RMS obtained from the 50 record1 in the CRD format but sometimes a "0" is left to fill in the space or the record is not provided. When the pass RMS reported in the 50 record1 in the CRD format is "0" or the record is not provided, the pass RMS is calculated from the pass using the multipe 11 records1 in the CRD format by averaging the bin RMS from the mean of raw accepted time-of-flight values minus the trend function (ps), if the number of raw ranges is greater than 5.

1For more information on these records please refer to the CRD format available here:

Replacement of Table 1 L with Table L1 and Table L2

Table 1 L has been replaced by Tables L1 and L2 which contain individual retroreflector information. Table L1 contains values over a 12-month span while Table L2 contains information over a 3-month span. In addition to breaking up the data by station, the new software also differentiates by wavelength. In addition, the pass RMS calculations follow the changes defined in "Information and Changes to Table 1" item 3.

Changes to Table 2

Item Handling Prior to 2020 2020 Onward
Records with filler information such as "--", "##", "✽", and blanks Set as "0" Line is ignored if the filler information is used in calculations for the table

Regenerated Report Card Data Prior to 2020

The new software has been used to generate the data for the previous years' reports (from May 2013 to December 2019); these are available for download.