Navigation, Fleet tracking, aviation, and emergency response — all of these rely on GPS to function. The Global Positioning System (GPS) is a “positioning, navigation, and timing (PNT)” service based on 24 operational satellites which are owned by the U.S. and managed worldwide by control stations. This post reviews the history of GPS satellites and how they laid the foundation for commercial GPS tracking.
Previously reserved only for military use, GPS is now available to everyone. For many, using a GPS device in the car to navigate traffic or having GPS location in their smartphones is now just part of daily life. We are so comfortable with this technology that we take it for granted.
In total, there are 31 operational satellites in the GPS constellation, with 3-5 additional satellites in reserve that can be activated when needed. The satellites circle the Earth two times a day at 20,200 km (12,550 miles) up. The U.S. Air Force monitors and manages the system, and has committed to having at least 24 satellites available for 95% of the time. See a map of the GPS control stations and pictures of GPS satellites and in the U.S. Government image library. Read More: Find out how GPS works.
History of the Global Positioning System (GPS)
Highlights in the History of GPS:
- 1957 — Soviet Union launches Sputnik I satellite.
- 1960s — U.S. Navy tracks U.S. submarines with satellite navigation.
- 1978 — Launch of NAVSTAR Block I GPS satellite.
- 1983 — U.S. announces that it will make GPS available for civilian use after Korean Air flight 007 shot down.
- 1989 — Magellan introduces NAV 1000, the first hand-held GPS device. First Block II satellite is launched.
- 1993 — Constellation of 24 satellite system becomes operational.
- 1995 — Full Operational Capability (FOC) declared.
- 2000 — Selective Availability discontinued by the U.S. Government.
- 2004 — Qualcomm successfully completes test of live assisted GPS on a mobile phone.
- 2008 — Block II satellite launched.
- 2016 — GPS IIF satellite launched.
The United States Department of Defense, seeking a reliable method of location, initiated the GPS or Navigation System with Timing and Ranging (NAVSTAR) project in the early 1970s. The first four satellites were launched in 1978. In 1995, once 24 satellites were in orbit, GPS was deemed to have reached full operational capacity.
SPS and PPS
GPS services were originally partitioned into the Standard Positioning Service (SPS), intended for the public, and the Precise Positioning Service (PPS) for military use. To protect U.S. security, the Department of Defense intentionally made the GPS signal for SPS less accurate, called Selective Availability (SA). SA was ended in 2000.
Despite some limitations in coverage and accuracy, GPS played a significant role in U.S. operations during the Gulf War in 1991.
Commercial GPS Tracking
The first GPS receiver for consumers was developed by Magellan. The NAV 1000 was 1.5 pounds, cost $3,000 and could run for a couple hours at a time on battery power. The high cost of satellite navigation meant that outside the military, only freight and delivery companies and select others could afford to use the system.
As GPS accuracy improved, many different industries could take advantage of GPS technology. GPS tracking is much more affordable these days. GPS trackers are lightweight and can fit in the palm of your hand.
GPS is essential to fleet management, especially for routing and dispatching. As stated on GPS.gov, “Using GPS technology to help track and forecast the movement of freight has made a logistical revolution, including an application known as time-definite delivery.”
GPS Today and Tomorrow
Today, there is a Global Navigation Satellite System (GNSS), including GPS, Russia’s GLONASS, Galileo, run by the European Union, and China is expanding its Beidu Navigation Satellite System. The U.S. Government is enhancing GPS with two additional signals for civilian applications, including one specifically for “safety-of-life applications,” and a fourth signal as well. GPS supports many different industries and is even used for low-Earth orbit space missions.
As the capabilities of technology continue to expand, one can only imagine what GPS technology looks like in the future. GPS information will be used to support warning systems for collisions and traffic violations, and smart transportation applications. Using physical maps, and asking strangers for directions is now a thing of the past. Here’s to what the future has to hold.