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	Director, Operational Test & Evaluation
FY97 Annual Report

NAVSTAR GLOBAL POSITIONING SYSTEM (GPS)

	Air Force ACAT IC Program 118 satellites (24 in operational constellation) Total program cost (TY$) $9602M Average unit cost (TY$) $66M Block IIR full production 3QFY89 Prime Contractor Block II, IIA satellites: Rockwell Block IIR satellites: Lockheed Martin Block IIF satellites: Boeing

SYSTEM DESCRIPTION & CONTRIBUTION TO JOINT VISION 2010

The NAVSTAR Global Positioning System (GPS) is a 24-satellite constellation that provides highly accurate, real-time, all-weather, passive, common-reference grid position, and time information to military and civilian users worldwide. GPS enables the military forces to precisely determine their position, velocity and time to (1) enhance command and control and coordinate battle tactics and support, (2) engage in strategic and tactical warfare, (3) maneuver efficiently on the battlefield, (4) provide accurate and timely fire support, and (5) facilitate combat service support operations. In addition, knowledge of exact position and time is essential for reconnaissance and intelligence missions. GPS provides the precision, velocity and time element of information superiority, and it serves as the cornerstone of the warfighter's ability to execute the Joint Vision 2010 operational concept of precision engagement.

GPS is an Air Force-managed Joint Service program and comprises three segments: space, control, and user equipment. The space segment consists of 24 satellites in semisynchronous orbits around the earth. The original Block I satellites were replaced with Block II/IIA satellites. Currently, Block II/IA satellites are being replaced with Block IIR on an as-needed basis.

The control segment consists of a master control station, four ground antennas, a prelaunch capability station, and five geographically dispersed monitoring stations. The control segment monitors satellite downlink signals and uploads corrections to diminish errors broadcast to users.

The user segment consists of numerous forms of GPS receivers that use satellite downlink signals to determine position, velocity, and precise time. These receivers are hosted on a multitude of platforms and are classified into three general categories: high-dynamic sets (5+ channels); medium-dynamic sets (2 channels); and low-dynamic sets (usually single channel). The 5-channel sets are used primarily by the Air Force and Navy on aircraft, ships, and submarines. The 2-channel sets are used mainly by the Army in heliborne configurations. The single-channel sets are generally used in hand-held applications.

DoD approved the NAVSTAR GPS program in December 1973. Full-scale development began in June 1979. By 1985, the Joint Program Office had launched 10 Block I satellites and developed the associated ground-control system software to support system test and checkout. The first production satellite launched successfully in February 1989. The Block I satellites were followed by 27 Block II/IIA satellites launches. IOC, which included the control segment, was declared on December 8, 1993.

The first Block IIR satellite was destroyed during launch when its Delta rocket exploded just after lift-off on January 17, 1997. The first successful launch of a Block IIR satellite was July 22, 1997 from Cape Canaveral Air Force Station, FL. There are 19 additional Block IIR launches planned. Block IIF satellites are under development.

GPS user equipment development began in June 1979 with receiver testing (using Block I satellites) in a variety of land, sea, and air vehicles. Since then, numerous versions of single-, 2-, and 5-channel receivers have undergone development and fielding. GPS user equipment achieved full-rate production approval in January 1992. Full operational capability was declared in November 1995 after completion of the Phase III IOT&E.

Space and control segment testing occurred in three phases. The Phase I IOT&E was conducted from 1989 to 1990, Phase II IOT&E from 1990 to 1992, and Phase III from 1992 to 1994. Each test phase was successful and led progressively to an approved final operational capability, with a complete 24-satellite configuration.

An OA, originally projected to begin in January 1997, was delayed because of the launch failure of the first Block IIR satellite that same month. The successful launch of a Block IIR satellite in July 1997 signaled the beginning of the OA, which is now proceeding toward completion early in FY98.

The Block IIA satellite constellation is fully operational. There was no operational testing of these satellites or their control function during FY97. The only tests performed were end-of-life tests.

On-orbit test and checkout of the first Block IIR satellite is ongoing.

It is too early in the program to make a final determination of the effectiveness and suitability of the Block IIR satellites. However, the Block IIR satellite launched in July is in its proper orbit and the navigation payload is functioning well. Operational testing did find that external in-band noise interference existed between the Nuclear Detection System and the crosslink/autonomous navigation system, rendering this first IIR satellite unable to perform the crosslink function. Future IIR satellites will be retrofitted with the appropriate fix prior to launch.

The Block IIR operational assessment will continue through 2QFY98. An initial operational test and assessment of the Block IIR portion of the GPS constellation is scheduled in 2000. This is based on a projected launch rate of four satellites per year and implementation of full functionality, including the auto-navigation capability. Based on the history of the GPS program, the results of the operational assessment, and the efforts to correct the interference problem, DOT&E believes the Program Office is progressing toward fielding an effective and suitable system.

The follow-on Block IIF satellite program will begin with first launch in 2002. An operational assessment of the space and control segment will take place with the first successful launch of a Block IIF satellite. An initial operational test and evaluation of a partial constellation will occur in the 2003-2004 time frame.