Difference Between GPS and GNSS | Bench Mark

In today’s world, navigation technology plays an essential role in our daily lives. Whether we’re driving to work, finding the fastest route to our favorite coffee shop, or navigating an unfamiliar location, most of us rely on what we commonly call GPS (Global Positioning System). However, what many people don’t realize is that GPS is just one part of a much larger system known as GNSS (Global Navigation Satellite System). Understanding the difference between the two can help us better grasp how our devices work and why we should update our terminology to reflect modern technology. You will see a huge difference in performance between a GPS only receiver and a multi-constellation GNSS receiver!

The Evolution of GPS and GNSS

How Navigation Satellites Work

What is GPS?

What is GNSS?

Why Multiple Navigation Constellations Matter

Trilateration And Why You Want More Satellites

The Accuracy of GPS vs. GNSS

Achieving Centimeter-Level Accuracy with RTK

Practical Applications of GNSS Technology

The Role of GNSS in Timekeeping

Future Developments in GNSS Technology

Final Thoughts

FAQs

The Evolution of GPS and GNSS

GPS (Global Positioning System) has been around for roughly 50–60 years, but it has only been widely accessible for everyday use over the past 20 years or so (We wrote an article on the history of GPS, check it out: GPS in Surveying – From Weapon of War to Everyday Tool). Today, it’s hard to imagine a world without GPS. From tracking Amazon packages to getting real-time traffic updates, GPS technology has transformed the way we live. Without GPS and GNSS, modern transportation, logistics, and even emergency response systems would be significantly impaired.

But what exactly is GPS? And how does it differ from GNSS? To answer these questions, we first need to understand how navigation satellites work.  

How Navigation Satellites Work

Navigation satellites orbit the Earth around 20,000 kilometers above the surface of the Earth and are travelling at speeds of ~7,000 km/h, completing an orbit of the Earth every ~12 hours. Despite their rapid movement, they are able to provide highly accurate timing and positioning data to the Earth’s surface, broadcasting the information over radio waves. 

On a very simple level, each satellite transmits two key pieces of information:

1. Time Code – A precise timestamp that is accurate to the nanosecond, thanks to the atomic clocks inside the satellites.
2. Position in Orbit – The exact location of the satellite in space at any given moment.

By receiving signals from multiple satellites, a GPS receiver can calculate its own position on Earth using a process called trilateration—which we’ll discuss in more detail later. For a more detailed look at what information these signals carry and what your receiver needs, check out my video: What is RTK and How Does it Work?

What is GPS?

GPS, or the Global Positioning System, was the original satellite-based navigation system. Developed by the U.S. Department of Defense, GPS consists of a constellation of 24 to 32 satellites orbiting the Earth, providing global coverage for positioning and navigation.

However, GPS is just one of many satellite navigation systems. Relying solely on one country’s system poses risks, including potential political and operational vulnerabilities. To address these concerns, other countries have developed their own independent navigation systems, which collectively make up GNSS.

What is GNSS?

GNSS stands for Global Navigation Satellite System, which includes multiple satellite constellations from different countries. Unlike GPS, which is a single system operated by the U.S., GNSS encompasses multiple global and regional navigation systems, including:

• GPS (United States of America)
• GLONASS (Russia) – The second to enter the scene after GPS. Built to be a direct competitor to GPS by the Soviet Union, it is now maintained by Russia. We have a video going over the history of this system you can find here: The History of Russian Satellites: How GLONASS Revolutionized Modern Surveying.
• Galileo (European Union) – As Russia increasingly moved away from the European Union, it became imperative for the European Union to invest and deploy their own system that could operate independently of the two systems. This resulted in Galileo (which came with a host of issues with the US Government wanting direct control. Makes for an interesting read: Delay Continues for Effort to Add Galileo Signal to US Military Receivers.
• BeiDou (China) – Originally deployed as a regional system only serving China, over the last 4 years it has been deployed globally. The newest third generation receivers offer some of the best signals available to civilians and really help separate the 6^th and 7^th generation receivers like the Hemisphere S631 (7^th) and the Hemisphere S321(6^th) in difficult environments.

Paired with GPS, these are the major global systems, but there are also several regional systems. 

• NavIC (India) – A regional navigation system developed by India to serve the Indian sub-continent. Not available in North America.
• QZSS (Japan) – A regional system designed for Japan and nearby areas. They employ high orbit geostationary satellites designed to help signals penetrate deep into urban canyons formed by sky scrapers, like those found in many large Japanese cities. Occasionally, in Western Canada and the Western US, you can pick up 1-2 of these satellites with your receivers.  

It is the combination of these navigation systems that make up the GNSS umbrella, rather than with GPS which is a component of GNSS. 

Why Multiple Navigation Constellations Matter

Using multiple navigation systems increases the likelihood of obtaining accurate positioning, especially in environments where signals may be obstructed or reflected by multi-path. For instance, if a building or tree blocks the signal from one satellite, a receiver can rely on signals from another constellation. This redundancy is particularly useful in urban environments and remote locations.

If you have ever tried to navigate with your phone under trees, you have probably noticed that the position on your screen is displayed by a very large circle, making it difficult to determine where you are. This is because as signals are reflected as they reach your device, the positional certainty becomes worse and worse. I actually did a video where I compared an iPhone to RTK to demonstrate why having more constellations and signals is so important. 

Trilateration And Why You Want More Satellites

To actually determine an accurate position, a GNSS receiver needs signals from at least three to five satellites. The process, known as trilateration, works as follows:

1. The receiver calculates its distance from each satellite based on the time it takes for signals to travel from the satellites to the receiver.
2. Using the known positions of the satellites and the measured distances, the receiver pinpoints its location on Earth.
3. Additional satellites help refine the accuracy and reduce uncertainties.

By having the ability to use more than 1 constellation you can calculate a position off any constellation. This decreases the time to obtain a solution, as you can use the best possible data to calculate your position. 

Achieving Centimeter-Level Accuracy with RTK

For professional applications like land surveying, construction, and precision agriculture, accuracy down to the centimeter is crucial. This level of accuracy is achieved using Real-Time Kinematic (RTK) positioning, which involves:

1. Base Station and Rover System – Two GNSS receivers are used: one stationary base station and one mobile rover.
2. Correction Data – The base station provides real-time corrections to the rover, significantly improving accuracy.
3. Centimeter Precision – By comparing signals between the two devices, RTK achieves an accuracy of 1–2 centimeters.

This technology has revolutionized industries that rely on precise positioning, allowing surveyors to replace traditional optical equipment with GNSS-based solutions. You can check out the above mentioned RTK video, or my video on repeatability: 

Practical Applications of GNSS Technology

Beyond everyday navigation, GNSS technology has a wide range of applications:

• Land Surveying – Establishing property boundaries, positioning construction sites, and mapping terrain.
• Agriculture – Precision farming, automated tractors, and crop monitoring.
• Autonomous Vehicles – Enhancing navigation for self-driving cars, drones, and robotic systems.
• Emergency Services – Dispatching ambulances, firefighting units, and police with precise location tracking.
• Maritime Navigation – Positioning ships and offshore drilling operations.
• Infrastructure and Utilities – Managing power grids, water pipelines, and telecommunications networks.

The Role of GNSS in Timekeeping

One lesser-known but crucial use of GNSS technology is in time synchronization. Many critical infrastructure systems, including financial markets, telecommunications, and data centers, rely on GNSS timing to ensure synchronized operations. 

Future Developments in GNSS Technology

Despite its widespread adoption, GNSS technology continues to evolve. Some key advancements on the horizon include:

• Higher Accuracy Signals – New civilian GNSS signals, such as the new High Accuracy Service (HAS) from Galileo, aim to provide accuracy anywhere on Earth to within 10 centimeters.
• Improved Performance in Challenging Environments – Enhanced signal processing techniques allow GNSS receivers to work better under trees, near buildings, and in other obstructed areas.

Expansion Beyond Earth – With the potential colonization of the Moon and Mars, there is ongoing research into implementing GNSS-like systems for extraterrestrial navigation.

Final Thoughts

GPS has become a household term, but the reality is that modern navigation technology relies on GNSS—a combination of multiple satellite systems working together to provide more reliable and accurate positioning. While GPS remains an integral part of this system, understanding the broader scope of GNSS can help us appreciate the technological advancements that make precise navigation possible.

As GNSS technology continues to improve, we can expect even more precise, reliable, and innovative applications, shaping the future of navigation both on Earth and beyond. Whether you’re a surveyor, a driver, or simply someone who relies on navigation apps, embracing the term GNSS can help us better describe the sophisticated technology that guides us every day.

FAQs

Bench Mark Equipment & Supplies is your team to trust with all your surveying equipment. We have been providing high-quality surveying equipment to land surveyors, engineers, construction, airborne and resource professionals since 2002. This helps establish ourselves as the go-to team in Calgary, Canada, and the USA. Plus, we provide a wide selection of equipment, including global navigation satellite systems, RTK GPS equipment, GNSS receivers, and more. We strive to provide the highest level of customer care and service for everyone. To speak to one of our team today, call us at 403-286-0333 or email us at [email protected].