Regional Network Analysis

The chosen regional GPS network consists of seven stations of the International GPS Service (IGS) plus the station SLAC M40. The figure below shows the geographical distribution of all eight sites.

The stations are referenced by the IERS/IGS 4-character site code of their DOMES numbers. The official sites are:

• AMC2: Colorado Springs, CO
• CASA: Mammoth Lake, CA
• DRAO: Penticton, BC, Canada
• JPLM: Pasadena, CA
• MDO1: Fort Davis, TX
• PIE1: Pietown, NM
• QUIN: Quincy, CA
• SLAC: Stanford, CA

The performance of the IGS stations may be viewed at the Continuous GPS Global Network Station Performance site of the Jet Propulsion Laboratory (JPL). The same institution provides long-term (several years) coordinate time series.

Here is a concise outline of the processing steps being preformed to derive accurate coordinates for SLAC M40:

• Download RINEX, orbits, and ERP files
• Orbit computation
• Synchronization of receiver clocks
• Creation of baselines
• Data cleaning
• Ambiguity resolution
• Daily free network solution
• Combination of daily network solutions and datum fixing

The GPS observation files are exchanged in the Receiver INdependent EXchange format (RINEX). ERP files contain the Earth orientation parameters (pole coordinates, UT1-UTC, UTC-GPStime).