Three decades after it first entered popular culture during the Gulf War, even a cursory review of articles about GPS aimed at a mass audience still will reveal a plethora of inaccuracies and misunderstandings, ranging from the trivial to the fundamental. Among my pet peeves, some for 20 years, are statements to the effect that GPS:
1. is a tracking technology
2. is the only such system
3. is responsible for routing errors
4. can operate indoors
5. receivers “talk” to the satellites
6. relies on triangulation
7. has 24 satellites in orbit
(For those of you picking up this magazine who are new to satellite navigation, the correct versions of those statements are below.)
Matteo Luccio
Additionally, GPS is taken for granted, with hardly any recognition for the engineers, technicians, U.S. Air Force service members and others who make the miracle happen, and for the fact that U.S. taxpayers foot the nearly $2 billion annual bill for the system, which is offered free to users worldwide. (All GPS program funding comes from general U.S. tax revenues. The bulk of the program is budgeted through the U.S. Department of Defense, which has primary responsibility for developing, acquiring, operating, sustaining and modernizing GPS. The U.S. Department of Transportation is responsible for funding the extra costs associated with new, civilian GPS upgrades beyond the second and third civil signals, and agencies with unique GPS requirements are responsible for funding them.)
While not as deadly as those about vaccines or as consequential as those about elections, misstatements about GPS lead to public confusion about threats to privacy and threats to the system. To help secure GPS, it behooves those of us who understand it the most to help educate the rest about it and correct misstatements, misunderstandings and misperceptions.
Matteo Luccio | Editor-in-Chief
mluccio@northcoastmedia.net
- Tracking a person, vehicle or other object requires pairing a GPS receiver with a transmitter, typically a cellular phone.
- It is one of four complete global navigation satellite systems (GNSS), the other three being the Russian GLONASS, the European Galileo and the Chinese BeiDou-3. There are also two regional systems, one Indian and one Japanese.
- Routing errors are caused by bad map data or bad routing algorithms.
- It requires a clear view of at least four satellites, unimpeded by terrain, buildings, roofs or even dense tree canopies.
- GPS receivers are just that and have neither the need nor the ability to transmit messages back to the satellites.
- Triangulation determines position by measuring angles. By contrast, GNSS determine position by measuring distances (between receivers and satellites), which is called trilateration.
- The are currently 30 operational GPS satellites and the number varies as some satellites are temporarily removed from service, older ones are decommissioned, and new ones are placed in orbit. Find the current status of the constellation here.
