GPS

With the press of a button on a phone, you can find where you are in the world with near-pinpoint accuracy. Something that would have seemed like magic not long ago is taken for granted today. However, it’s no miracle, and the most common system used today for navigation and much more is called the Global Positioning System or GPS for short. Keep reading to learn more about GPS, its definition, uses, and importance.

GPS Definition

The Global Positioning System as of 2022 is a series of 31 satellites orbiting the Earth. These satellites connect with receivers on the ground and can pinpoint the exact location of the receivers. GPS originated as a project with the US Department of Defense, and its first satellite was launched in 1978. Today, GPS is still operated by the United States Space Force but is free for civilian use worldwide.

GPS is considered a global navigation satellite system or GNSS for short. Other GNSS exist today, such as the European Union’s Galileo system, but GPS remains the most comprehensive and widely used. To receive the most complete and precise data on geolocation, at least four GPS satellites need to be connected to the receiver.

GPS provides users with their latitude and longitude, as well as their altitude and exact time. It’s important to note that GPS satellites do not send any information directly to a receiver. Instead, the receivers calculate how far they are away from the satellites, and when they get the signal from at least four, they can calculate its coordinates and altitude on Earth.

Fig. 1 - A never-launched GPS satellite on display in San Diego

The overall GPS system can be split into three segments: the space segment (satellites), the control segment (monitoring stations), and the user segment (receiver).

Types of GPS

GPS receivers can take different forms depending on who is using them and for what purpose:

Personal

Chances are you’ve used GPS in one form or another, either through a smartphone, handheld device, or one integrated into a car. GPS devices for personal use are meant to be used by the general public for things like navigating to a destination or helping locate themselves. GPS devices for personal use are the most common type of receiver and are used around the world.

Commercial

As opposed to personal GPS devices, commercial ones are used by companies and businesses. There might not be much practical difference between personal and commercial devices, but oftentimes there is more integration with other systems. For example, a delivery company may use GPS to help track its vehicles, and it can be used in combination with the computer system they use to track where items were delivered.

Military

GPS was originally developed by the US military for its own use but began to open to public use during the 1980s. GPS is still used by the US military and allies today for guiding weapons and tracking vehicles. In fact, the US military has access to a more precise and accurate version of GPS and can even limit GPS access to other countries in times of conflict.

Uses of GPS

Now that we’ve gone over some of the types of GPS, let’s go in-depth on some major uses of GPS.

Locating

Being able to know your location on Earth is the most fundamental purpose of GPS and while it seems simple, geolocating can be very useful to all sorts of industries. GPS is used to track things like weather balloons, farm equipment, and even animals for wildlife research. Geolocating via GPS can also save people’s lives. If someone ends up in an emergency situation in a remote area, GPS beacons notify authorities of someone’s location and they can be rescued.

Fig. 2 - Handheld GPS receiver

You may have personally used GPS to track a lost smartphone or find out where you are. The logistics industry also relies upon GPS to track vehicles like planes, trucks, and trains to ensure they are all getting to their destinations on time and efficiently.

Navigation

Functioning in tandem with map software, GPS enables users to navigate in real-time. Being able to type in a location and get the exact directions from where you are with updates during the journey is not just convenient for getting to your friend’s house, but also crucial to maritime shipping and emergency response. GPS helps eliminate human error in using traditional methods like a map and compass, but maps have to be up to date as well for GPS navigation to be most accurate.

Surveying and Cartography

The science of taking measurements of the earth’s surface is called surveying. Surveying has been around for centuries and was fundamental for cartography. While surveying today is still used for creating maps, it’s more commonly used in construction projects, where satellite imaging and remote sensing are unable to be as precise as needed for the projects. With the advent of GPS, surveying has become more streamlined and accurate, allowing surveyors to know exactly where they are and calibrate their equipment.

Importance of GPS in Geography

Because it is a geographical tool, it’s no surprise that GPS is important to the field of geography. Let’s discuss some of the importance of GPS in geography next.

Mapping

Being able to accurately locate and illustrate the Earth’s physical features is fundamental to geography. Everything from the peaks of mountains to the lowest point of a valley has a coordinate, and GPS enables that coordinate to be accurately accounted for. The more accurately the Earth’s features can be mapped, the more precise geographical research can be.

Physical Geography

GPS is also fundamental to physical geography studies. Physical geography is the subset of Geography that studies changes and patterns in the Earth’s environment. This includes things like studying glacial movements, how coastlines change over time, and the distribution of the Earth’s species. GPS is incredibly useful for identifying changes over time.

Fig. 3 - Griffon vulture with GPS tracking antenna

A biogeographer studying an animal’s migration can use GPS receivers attached to the animals to track where they go. The ability of GPS receivers to measure elevation means they can pick up subtle changes in the Earth’s surface over time.

Human Geography

In terms of human geography, GPS is useful for undertaking research in transportation and social geography. GPS data on where personal vehicles go can help inform urban planners and transportation geographers of ways to better improve road networks and traffic signals. In terms of sociology, researchers might use GPS data from cell phones to get an idea of where people go and what places are important to the social fabric of an area.

Disadvantages of GPS

Now that we’ve discussed how GPS is a useful tool, let’s go into some disadvantages of GPS.

Special Equipment and Software Required

GPS is available to anyone worldwide, but a receiver is needed to use it. Receivers can vary in cost and dependability. While this isn’t much of an issue for things like research projects, it could be a problem if in a survival situation and a GPS-capable device breaks or runs out of battery. For a GPS device to be most useful, it’s integrated with some sort of software like a map application. Most basic navigation apps are free, but to fully take advantage of GPS for something like tracking delivery vehicles, more costly software is needed.

Privacy and Surveillance

Using GPS features on a phone can be helpful to find where you are or somewhere to eat nearby. However, who has access to those data is a concern of privacy advocates. Apps and companies use GPS data to target advertising and those data could end up in places the user never intended. There are also worries about the ability of governments to monitor citizens using GPS and potentially violating their rights in the process. While GPS is an incredibly useful tool, it's also brought about surveillance capabilities and privacy concerns like never before.

Limits on Civilian Usage

Because GPS is owned and operated by the United States Space Force, there are limits on its usability to the general public and, by extension, other countries’ militaries. The US military has access to a more precise version of GPS, and also doesn’t allow GPS to be used above 60,000 feet or for vehicles traveling more than 1,000 miles per hour. While this does deter the usage of GPS for weapons, it also limits its effectiveness for some research situations, especially for aerospace engineering and meteorology.