System Performance Standards (2015)

In 1996, at the International Workshop on Laser Ranging in Shanghai, the SLR community established a Satellite Pass Performance Standard of 1500 passes; this standard was adopted by the ILRS at the 1998 workshop in Deggendorf, Germany. The standard was broken down into LEO (1000 passes), LAGEOS (400 passes) and the newly introduced HEO satellites (100 passes). At the time, the ILRS had far fewer satellites on its tracking roster.

We recognized that stations had different cloud cover conditions, different levels of technology and operational readiness, and different staffing levels. The standard was set conservatively to give stations a target for improved performance on one hand and to recognize high achieving stations on the other.

Since that time our technologies have evolved, our procedures have improved, and we have considerably more ranging experience. We are more successful with daylight tracking and our retroreflector designs are more efficient. Above all, however, the number of targets has increased dramatically. As a result, it is now time to set a greater expectation. As of late 2015, the network is tracking 23 LEO satellites, 3 LAGEOS–class satellites (including LARES), and 30–50 HEO (including GNSS and GEO) satellites.

The Governing Board has set a new ILRS Pass Performance Standard at 3500 passes per year. In redefining the ILRS Pass Performance Standard we considered the following guidelines as a basis:

  • 2 passes per week on each LEO satellite (2300 LEO passes per year)
  • 4 passes per week on each LAGEOS satellite (600 LAGEOS passes per year)
  • 2 passes per week on each HEO satellite (>3000 HEO passes per year)

Data quality guidelines are:

  • 1 mm LAGEOS NP precision
  • 5 mm short term bias stability (1)
  • 2 mm long term bias stability (2)

(1) the standard deviation about the mean of the pass-by-pass range biases (see global report card - Monthly | Quarterly).

(2) the standard deviation of the monthly range bias estimates for at least 8 of the last 12 months (see global report card -
Monthly | Quarterly).

Operational compliance guidelines are:

  • Data delivery within 2 hours (data latency)
  • Specified ILRS NP data format (CRD)
  • Current site and system information form submitted and maintained (i.e., site log, system log)

The full text for the 2015 ILRS Pass Performance Standard is available. The 1998 standard is also available.