TAT2 description.docx

The Architecture Evolution Program (AEP) has provided a modernized GPS Master Control Station (MCS) to the 2nd Space Operations Squadron (2SOPS) at Schriever Air Force Base. A significant part of this modernization was the addition of GPS observable and navigation data from the GPS Monitor Station Network (MSN) of the National Geospatial-Intelligence Agency (NGA). The MSN is comprised of 11 operational monitor stations (MS) and a MSN Control Center (MSNCC) located in St. Louis, MO. A dedicated communication line was established between the MSNCC and the MCS as part of AEP to flow NGA MSN data in real-time to the MCS. In 2000, NGA and the Space and Geophysics Laboratory (SGL) of Applied Research Laboratories; The University of Texas at Austin (ARL:UT) proposed and implemented a temporary means to take advantage of the existing communication line to provide monitoring data to 2SOPS until the initial version of AEP was available at a later date. The implementation involved a tail circuit from the dedicated MSNCC-MCS communication line which terminates at a workstation at the Payload System Officer (PSO) position. This machine is designated as the Temporary Analysis Tool at 2SOPS (TAT2). The TAT2 presents a display of all satellite range residuals to the PSO for all NGA stations used by the MCS. It can also present several of the displays used by NGA personnel to monitor SV health status, GPS receiver tracking, station system status, and data flow from the stations to NGA and USAF. A detailed pseudorange residual analysis tool (RAT) is also provided for use by 2SOPS DOAN personnel and MCS support contractors as an observed range deviation (ORD) tool.

As the name implies, TAT2 was envisioned as temporary means to provide the PSO with a GPS monitoring capability using the additional NGA MSN data. The original plan was to remove it after AEP was fully deployed. However, as experience accumulated, the PSO and MCS support personnel came to rely on the TAT2. This is in part because it provides a real-time fully independent source and presentation of satellite performance as viewed with ORD data. Both the source and flow of the data is independent of the AEP processes. Additionally, a tool called the RAT (Residual Analysis Tool) daemon is being used by DOAN and MCS support personnel to extract archived data from the NGA MSNCC for long term trending and other analyses in post-processing for 2SOPS.

As utilization grew, formalization was required to transform the TAT2 into a operational asset. The original TAT2 platform was a standalone PC with a monitor using the IBM OS/2 operating system. System administration was performed by ARL:UT. Under previous tasking and funding, ARL:UT replaced the original PC hardware and operating system was replaced with a Sun Microsystems SunBlade 100 running Solaris version 8, in part to comply with USAF approved equipment and software. (The NGA MSN had also migrated to a Sun/Solaris architecture.) Once TAT2 formally became an operational asset, MCS Level 1 and 2 support contractors assumed responsibility for testing and system administration of TAT2 software and system operation. ARL:UT's role as software developer and provider of software updates has continued.