Infrastructure Past, Present, and Future Casebook/GPS: Global Positioning System

This casebook is a case study on Global Positioning Systems (GPS) by Andrew Shibley and Sean Thiltgen as part of the Infrastructure Past, Present and Future: CEIE 499-002 Spring 2023 course at George Mason University's Schar School of Policy and Government and the Volgenau School of Engineering Sid and Reva Dewberry Department of Civil, Environmental, and Infrastructure Engineering. Modeled after the Transportation Systems Casebook. Under the instruction of Prof. Jonathan Gifford.

GPS Satellite

Summary edit

Global Positioning Systems, better known as GPS, is a United States owned utility and technology that has changed infrastructure as we know it. Overall, GPS provides users with positioning, navigating, and timing (PNT) services. The system consists of three different segments. These are: the Space Segment, the Control Segment, and the User Segment. The United States Space Force controls and maintains both the Space and Control Segments.[1]

    The Space Segment consists of multiple satellites that transmit data to users. The US space force has been operating 31 satellites for over ten years now. The satellites in the “GPS constellation” as it is called, are arranged into six equally-spaced planes surrounding the Earth. Each plane contains four spaces that are occupied by satellites. This arrangement ensures that users can view at least four satellites from almost any point on the planet. The Space Force normally flies more than 24 GPS satellites whenever the satellites in each plane are repaired or decommissioned. Usually, these extra satellites improve GPS performance.[1]

    The Control Segment consists of a network of facilities around the globe that track the GPS satellites, monitor their transmissions, perform analyses, and send commands to the GPS constellation. The current Operational Control Segment (OCS) is comprised of a master control station, a secondary master control station, eleven antennas used for commands, and sixteen monitoring sites. The locations of these facilities can be seen in the Maps of locations and diagrams section of this casebook.[1]

The User Segment, as the name implies, revolves around the user of GPS. Much like the Internet, railways, or highways, GPS is an essential element of global infrastructure. The innovation of GPS has directly led to the development of hundreds of applications affecting every aspect of life today. GPS technology is now in everything from cell phones to cars, airplanes, and ATM's. GPS is also critical to U.S. national security, and its applications are integrated in almost every aspect of U.S. military operations. Nearly all new military technologies integrate GPS.[1]

Actors and Institutions Involved edit

Public Actors edit

National Executive Committee for Space-Based Position, Navigation, and Timing: Executive Level Advisory Committee that provides guidance to its underlined member agencies and organizations.
Under this Committee the following US government organizations and agencies operate, manage, and/or use US-owned GPS systems. [2]
US Department of Defense - The DoD is the main operating agency for US GPS Systems and acquires, contracts, sustains, and secures its satellites, control segments, and military use equipment.
US Department of Transportation - Operates the Wide Area Augmentation System (WAAS) which provides augmented navigation information for aircraft in the United States. DoT also serves as the lead civilian agency on GPS-related issues.
US Department of State - Coordinates US foreign policy objectives regarding GPS and leads US delegations to international events, organizations, and committees which handle GPS spectrum allocations and discussions.
US Department of the Interior - Uses GPS for a wide variety of government activities, including: surveying; geographical information systems; and land management.
US Department of Agriculture - Conducts research for applications of GPS in agriculture alongside integrating GPS technology in cartography and fire suppression/protection plans.
US Department of Commerce - Manages and operates the Continuously Operating Reference Stations (CORS) network in the United States, as well as co-managing the radio spectrum used by GPS with the FCC.
US Department of Energy - Utilizes GPS systems to synchronize, and manage the US Electric Grid including detecting and managing relay stations and fault protection systems.
US Department of Homeland Security - Reports on and maintains databases covering domestic and international disuse and interference to civil GPS usage. Provides civil GPS support through the Coast Guards Navigational Center (NAVCEN) and the Civil GPS Service Interface Committee (CGSIC).
US Joint Chiefs of Staff - Oversees and validates requirements for the modernization of current and future GPS Systems under the GPS III project.
National Aeronautics and Space Administration - Operates both the Global Differential GPS System and reference stations for the International GNSS Service. NASA also provides research on new technology for space-borne GPS systems and new uses for aging satellites.

Private Actors edit

Lockheed Martin - Since 1997 Lockheed Martin has been the main manufacturer of US GPS Satellites, and continues to be the main private company tasked with the continued production and modernization of the space-borne fleet.
TomTom - A Dutch GPS receiver manufacturing company and one of the first to offer commercial civilian GPS receivers in the form of SatNav.
Raytheon - Raytheon was awarded the Next Generation GPS Operational Control System (OCX) contract , which aims to work in conjunction with Block III modernization in offering better more robust control systems.

Timeline of Events edit

Early Stages edit

1960’s: The origin of GPS starts in the Sputnik era when scientists were able to track the satellite with shifts in its radio signal. The United States Navy started conducting satellite navigation experiments to track US submarines carrying nuclear missiles. Submarines were able to see the satellite changes and find the submarine's location within minutes.[3]

Post 1960: The Advanced Research Projects Agency (ARPA) used the principle from the Sputnik era to develop “Transit”. This was the world's first global satellite navigation system. The first satellite was capable of providing navigation to military as well as commercial users. By 1968 thirty-six satellites were fully operational. Transit is known for improving the accuracy of maps by nearly two orders of magnitude. This helped to increase the acceptance and overall need of satellite navigation.[3]

Early 1970s: Using previous ideas from Navy scientists, the Department of Defense started to use satellites to support their proposed navigation system. They then created this navigation system and launched the first “Navigation System with Timing and Ranging” (NAVSTAR) satellite in 1978. The satellite system would become fully operational in 1993.[3]

1972: Colonel Bradford Parkinson of the Air Force was tasked with overseeing the satellite navigation program. Parkinson led a team in creating a concept that took the best parts of TRANSIT. This system proposal received Defense Department approval in December of 1973 for a 1-way system of 24 satellites.[3]

1974: This approach began when the Air Force started development of the first of a series of Navstar satellites, the ground control system, and various types of military user equipment.[3]

Making Progress edit

1978: The first “Block I developmental Navstar/GPS” satellite launched. Three more were launched at the end of this same year.[3]

1980: Additional GPS Block I demonstration satellites were launched.

1983: Ronald Reagan authorized the use of Navstar, now known as GPS, for commercial airlines in an attempt to improve navigation and safety for air travel.[3]

Road Towards Civilian Use edit

1984-1989:  Authorization was given to provide free access of GPS data to industries that were not the U.S. military. This became the first step towards civilian usage. [3]

By 1989, commercially available handheld GPS devices would hit the market. [3]

Throughout the 90s, GPS technology continued to improve.

Benefon GPS

1999: GPS technology appeared for the first time in a cellphone when Benefon released Benefon Esc!. This was a phone that had GPS that would pave the way for more. During this time, Global Positioning Technology also began to show up in automobiles.[3]

2000: The government approves plans to add three additional GPS signals for non-military use. As a result, GPS signals became 10 times more accurate for civilians. During this time the price for GPS receiver chips dropped from $3,000 to $1.50.[3]

Present Day edit

2005: By this time GPS satellites included five different configurations with different capabilities.

2018: The first GPS III satellite was launched at SpaceX falcon 9.

2019: The second satellite was launched.

2020: The third and fourth satellites were launched.

The remaining six satellites are scheduled to be launched in 2023.

Funding and Financing edit

GPS is owned and operated by the United States government and is primarily funded by the US Department of Defense (DoD).  After the development of GPS began in the 1970s it was initially funded by the US military for use in their operations. However, as the system quickly proved to have multiple civilian applications which included navigation, surveying, mapping, and timing, the US government started to fund the system's expansion for civilian use.

In the early days of GPS, around 1983, President Ronald Reagan issued a directive that made GPS freely available for civilian use. This led to increased demand for GPS devices and services, which, in turn, created revenue for private companies that developed and sold GPS products.

Today, the US government continues to fund the GPS system's maintenance and upgrades. This can be very expensive. In 2019, the DoD budgeted $1.4 billion for GPS operations, including $837 million for satellite procurement and $482 million for ground control.[4] In addition, congress provided about $22 billion to fund the GPS program in the 2022 fiscal year.[5]

According to the official US government GPS webpage, the rest of the money to fund GPS actually comes from taxpayer dollars. The money is then budgeted through the Department of defense. In addition, per section 5 of the Memorandum on Space Policy Directive 7, the Department of Transportation is responsible for funding civil signal performance monitoring and overall any civil capabilities involving GPS. In other words: non-military application. [5]

Apple Inc.

In addition to the government's funding, private companies also invest in GPS technology. These companies typically focus on developing GPS enabled devices and applications. Such devices include: smartphones, fitness trackers, and vehicle navigation devices. Some of the major companies that help finance and develop GPS technology include Garmin, TomTom, and Apple.

The US government also partners with other countries to finance and develop GPS technology. The European Union, using the same technology as the US, has developed its own satellite navigation system, called Galileo, which is designed to be compatible with GPS. In 2004, the US and the EU signed an agreement establishing this cooperation.[6] The European Union has invested over $14 billion in the Galileo program and continues to fund its development and operation.

Overall, the US government primarily funds and operates the GPS system through money earned from taxpayer dollars. However, private companies also contribute to its development and use. The government's investment in GPS technology has generated significant profit for private companies and has led to numerous civilian applications using the system. In addition, partnerships with other countries have helped to expand and improve GPS technology, making it a great tool for navigation, surveying, and mapping.

Institutional Arrangements edit

The Global Positioning System is owned by the United States government and operated by the United States Space Force. The arrangements involved with GPS are quite complicated and involve a number of different entities and institutions.

At the highest level, GPS is governed and overseen by the United States government, specifically the National Space-Based Positioning, Navigation, and Timing (PNT) Executive Committee. The Executive Committee was established by presidential directive and coordinates GPS related matters across multiple federal agencies. The committee is chaired by the Deputy Secretary of Defense and includes representatives from a number of government agencies, including the Department of Commerce, the Department of Homeland Security, the Department of Transportation, and NASA. The Executive Committee is responsible for setting policy and providing guidance for the GPS program.[7]

Seal of the United States Space Force

As stated before, the regular operation of the GPS system is carried out by the United States Space Force, a branch of the US military responsible for space operations. The Space Force operates a number of different satellite systems, including the GPS constellation, which is made up of more than two dozen satellites in orbit around the Earth. The Space Force is responsible for maintaining and upgrading the GPS system, as well as ensuring its security, stability, and durability.[8]

In addition to the government, there are a number of private companies that provide services related to GPS. These include manufacturers of GPS devices and software, as well as companies that use GPS data to provide location services used in navigation. For example, in 2018, Apple worked with the Department of Defense to test a new GPS signal that would provide more accurate location data for iPhones. These companies are regulated by the Federal Communications Commission (FCC)

One of the most important institutions involved with GPS is the International GNSS Service (IGS). The IGS is an international network of more than two hundred organizations that provide GPS and other Global Navigation data to support scientific research. The IGS collects data from a number of different sources and uses this data to create accurate positioning information that can be used for earthquake monitoring, climate research, and other purposes.[9]

Another important arrangement involving GPS is the Federal Radionavigation Plan (FRP). The FRP is a document that outlines the United States government's policies and plans for radionavigation systems, which include GPS. The FRP is updated regularly when changes happen with technology and policy. The FRP also can be used as a guide for government agencies and private companies involved with GPS.[10]

There are also a few international agreements that oversee the use of GPS. These include agreements between the United States and other countries in regard to the use of GPS for military and civilian purposes. These also include agreements between the United States and international organizations such as the International Civil Aviation Organization (ICAO) and the International Maritime Organization (IMO).

The institutional arrangements involved with GPS are complex and involve a number of different government agencies, private companies, and international organizations. These arrangements are designed to make sure GPS is as effective as possible and to promote the use of GPS for research and a wide range of applications.

Maps of Locations and Diagrams edit

GPS Constellation

This is an imagining of the GPS constellation.

Map showing GPS ground locations

Policy and Technical Issues edit

Public Availability and Policy edit

Originally, when GPS was first created the main two frequency bands were split between public access and a private government use frequency creating the "Selective Availability" system. As the public began to rely more and more on GPS for everyday navigation and positioning the lower civilian band began to show its limitations. With accuracy ranging from a minimum of 3.5 meters to upwards of 15 the US government recognized the importance of GPS in everyday civilian life. Following this recognition in 1996 GPS was classified as a national asset and important infrastructure, thus giving the public access to both the upper and lower L bands, improving accuracy up to 3.5 meters and providing the public with access to a signal that was non-degraded due to atmospheric interference.

Following the discontinuation of the "Selective Availability" system in 2000, the cost of commercially available receivers dropped considerably, allowing for an even wider public access to GPS positioning. As a consequence current Block I and Block II GPS satellites were unable to meet the demand of users, thus necessitating the Block III modernization project.

Technical Issues edit

GPS systems rely on "line-of-sight" between the receiver and at minimum 4 satellites overhead in orbit. As this line-of-sight decays, due to inclement weather or the receiver being blocked in buildings with high amounts of internal copper wiring. Due to high amounts of interference the accuracy of data being received by the receiver becomes highly inaccurate giving a high margin of error to position data.
During the 1990's this issue was not as prevalent as the modern day, with many modern buildings having more dense and expansive wiring throughout. Some solutions to this issue of inaccuracy position or outright position data not working in buildings is through supplementing satellite based position data with information that can be gathered by Wifi or Cellular signals. This helps to bypass the main constraint of GPS which requires it to be "in view" of the reciever. Companies such as Apple and Google have begun to implement this system to provide greater accuracy when near objects, or in buildings, that could otherwise block the signals coming off of GPS satellites.[11]

Potential Vulnerabilities and Future Issues edit

GPS is uniquely vulnerable for several reasons and has specific systems that are able to be disrupted in both sophisticated and unsophisticated ways which has presented issues in its use. One such vulnerability to the GPS system is the US energy grid’s reliance on GPS timing for use in relays as well as maintaining the phase timing across changing electrical systems. According to the US Department of Energy disruption of these systems has the potential to cause small scale black outs or disruptions to the United States power grid.[12] Disruptions such as this have been minor, although have the potential to increase given wave-length crowding in Low Earth and Medium Earth Orbit.
Several International Conferences have carved out space on the electromagnetic spectrum in the L1, L2 and L5 bands[13], which has allowed for GPS to remain largely noise free since its creation. Since the late 1990s more and more nations have begun to create their own satellite programs, as well as competing GPS systems. GLONASS and BeiDou are examples of both Russian and Chinese satellites systems that directly compete for commercial end-user use on the ground.[14] These efforts alongside the increase in commercial and civilian satellite programs has caused issues of wave-length crowding in low earth and mid earth orbits. Block III and the OCX system is currently attempting to address some of these problems. This is being achieved through providing more error correcting software and new ground stations that can ensure that signals from GPS satellites are accurate and reliable given the greater crowding of radio space in orbit and on the ground.[15]

Discussion Questions edit

Do you think that GPS should continue to be solely controlled by the US government?

Given GPS's interconnectivity with modern day navigation and day-to-day life is there a need to increase its available bandwidth and security systems?

References edit

  1. a b c d Invalid <ref> tag; no text was provided for refs named :1
  2. National Executive Committee for Space-Based Positioning, Navigation, and Timing (PNT). "Federal Agencies".{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. a b c d e f g h i j k “Brief History of GPS: The Aerospace Corporation.” Aerospace Corporation, March 1, 2023.
  4. Erwin, Sandra. “Pentagon Space Procurement and R&D Budget Is on an Upward Trend. How Long Can This Last?” SpaceNews, January 23, 2023.
  5. a b "Program Funding.” Program Funding. Accessed March 20, 2023.,ending%20September%2030%2C%202022).&text=President%20Biden's%20FY%202023%20budget,billion%20for%20the%20GPS%20program.
  6. “International Cooperation.” International Cooperation. Accessed March 20, 2023.,GPS%20and%20Europe's%20Galileo%20system.
  7. “Charter.” Charter of the National Executive Committee for Space-Based Positioning, Navigation, and Timing. Accessed March 22, 2023.
  8. “Space Segment.” Space Segment. Accessed March 22, 2023.
  9. NASA. NASA. Accessed March 27, 2023.
  10. “Radionavigation Systems Planning.” U.S. Department of Transportation. Accessed March 27, 2023.
  11. "Control Access Point Inclusion in Location Services". Google. Retrieved 1 April 2023.
  12. "Edge Detection of Grid Anomalies". Darknet.Ornl.Gov U.S. DoE. Retrieved 2 April 2023.
  13. "Time and Frequency, GPS". NIST. Retrieved 3 April 2023.
  14. "Other Global Navigation Satellite Systems (GNSS)". Retrieved 2 April 2023.
  15. "GPS Next-Generation Operational Control System". Raytheon Intelligence and Space. Retrieved 30 March 2023.


  1. “The Global Positioning System.” GPS Overview. Accessed March 15, 2023.,segment%2C%20and%20the%20user%20segment.


  1. “Program Funding.” Program Funding. Accessed March 20, 2023.,ending%20September%2030%2C%202022).&text=President%20Biden's%20FY%202023%20budget,billion%20for%20the%20GPS%20program.