GNSS vs GPS: What’s the Difference?

GNSS (Global Navigation Satellite System) is the umbrella term for every satellite navigation system in the world. GPS (Global Positioning System) is one of those systems, owned by the United States.

Think of it like “smartphone” versus “iPhone.” Every iPhone is a smartphone, but not every smartphone is an iPhone. In the same way, GPS is a GNSS, but GNSS covers much more than GPS.

Here’s a breakdown of GNSS vs GPS, how each system works, and why the difference matters if you’re thinking about tracking a car.

GNSS vs GPS: Side-by-Side Comparison

What Is GPS?

GPS is a satellite-based radionavigation system built by the U.S. Department of Defense. Today it’s operated by the U.S. Space Force. It began as a military project in the 1970s and became fully operational in 1995. Civilians have been able to use it free of charge for decades.

The system has three parts:

• The space segment: a constellation of roughly 31 operational satellites orbiting about 12,550 miles (20,200 km) above Earth in medium Earth orbit.
• The control segment: ground stations that monitor the satellites, correct their clocks, and update their orbital data.
• The user segment: every GPS receiver on the planet, including the chip in your phone, your car’s navigation unit, and the tracker hidden under a fleet van’s dashboard.

Each satellite carries highly accurate atomic clocks and continuously broadcasts its position and the exact time. A receiver measures how long those signals take to arrive, works out its distance from each satellite, and uses a process called trilateration to calculate its position. You need signals from at least four satellites to get latitude, longitude, altitude, and a clock correction.

GPS broadcasts on several frequencies. The best known is L1 (1575.42 MHz), which nearly every consumer device uses. The newer L5 signal is stronger and more resistant to interference.

Pros and Cons of GPS

Pros

• Free for anyone to use, with no subscription needed to receive the satellite signal
• Global coverage 24 hours a day, in any weather
• Supported by virtually every navigation chip, phone, and tracking device on the market
• Mature, well-maintained system with ongoing upgrades through newer GPS III satellites
• Works with WAAS corrections across the U.S. for improved accuracy
• Reliable enough for most everyday navigation and vehicle tracking in open sky

Cons

• Relies on a single constellation, so there’s no backup if signals are blocked or disrupted
• Fewer satellites in view, which can reduce accuracy in cities, canyons, and under heavy tree cover
• Civilian signals can be jammed or spoofed with relatively cheap equipment
• Signals can’t pass through buildings, tunnels, or underground parking garages
• Older single-frequency receivers can’t use the stronger L5 signal
• Typical consumer accuracy of about 16 feet may not be enough for precision work

What Is GNSS?

GNSS covers all satellite navigation constellations, whether they serve the whole globe or a single region. When a device says it’s GNSS-capable or “multi-constellation,” it usually means it can lock onto satellites from more than one of these systems.

Pros and Cons of GNSS

Pros

• Access to more than 100 satellites across GPS, GLONASS, Galileo, and BeiDou
• More reliable fixes in urban canyons, mountain roads, and wooded areas
• Faster time to first fix, especially after a cold start
• Built-in redundancy if one system has an outage or local interference
• Better satellite geometry, which improves overall position accuracy
• Multi-frequency receivers can correct for ionospheric errors for sharper accuracy

Cons

• Multi-constellation receivers can draw more power, which matters for battery-powered devices
• Hardware tends to cost more than basic GPS-only chips
• Not every device supports every constellation, so “GNSS” on a spec sheet can mean different things
• Still blocked indoors and underground, just like GPS
• Remains vulnerable to jamming and spoofing across all frequencies
• Little noticeable improvement over GPS alone in wide-open rural areas

The Four Global Constellations

• GPS (United States). The original and still the most widely used. It’s reliable, well maintained, and supported by essentially every navigation chip made.
• GLONASS (Russia). Russia’s system was developed during the Soviet era and restored to full global coverage in 2011. Its satellites orbit at a slightly lower altitude and a steeper inclination than GPS, which gives it good coverage at high northern latitudes.
• Galileo (European Union). Run by the European Union and the European Space Agency, Galileo is the only global system under civilian rather than military control. It’s known for high precision, and its free open service is accurate to within about one meter with dual-frequency receivers.
• BeiDou (China). China’s BeiDou Navigation Satellite System completed its global third-generation network (BDS-3) in 2020. It has a large constellation that mixes medium Earth orbit satellites with geostationary and inclined geosynchronous ones, which gives it particularly dense coverage over Asia.

Regional Systems

Two smaller systems add coverage in specific parts of the world:

• QZSS (Japan): the Quasi-Zenith Satellite System improves accuracy over Japan and the Asia-Pacific region, especially in cities with tall buildings.
• NavIC (India): formerly known as IRNSS, it covers India and the surrounding area.

Augmentation Systems

There are also satellite-based augmentation systems (SBAS). These don’t calculate your position themselves. Instead, they send correction data that makes existing signals more accurate. In the U.S., the FAA’s Wide Area Augmentation System (WAAS) was designed to help aircraft land safely, but many consumer receivers use it too. Europe’s equivalent is EGNOS.

Why Multi-Constellation GNSS Usually Performs Better

On paper, GPS on its own is accurate. According to the U.S. government, a GPS-enabled smartphone is typically accurate to within about 16 feet (4.9 meters) in open sky. The catch is the phrase “open sky.” Real life is messier than that.

More Satellites in View

A receiver that only listens to GPS might see eight to twelve satellites at a time. A receiver that also tracks Galileo, GLONASS, and BeiDou could see more than thirty. More satellites give the receiver more options, so if a building or hillside blocks a few of them, there are still plenty left to calculate an accurate position.

Better Performance in Urban Canyons

Downtown streets lined with skyscrapers are known as urban canyons. Signals bounce off glass and concrete before reaching the receiver, which causes an error called multipath. With more satellites to choose from, a GNSS receiver can lean on the ones with a clear line of sight and ignore the distorted ones. That matters a lot when you’re trying to work out which side of the street a car is parked on.

Faster Fixes

Time to first fix (TTFF) is how long a device takes to work out its position after being switched on or losing signal. Multi-constellation receivers can often get there quicker, especially after a “cold start,” when the device has no recent satellite data stored.

Better Satellite Geometry

Accuracy doesn’t just depend on how many satellites you can see. It also depends on how they’re spread across the sky. Satellites bunched together in one patch of sky produce a weaker fix than satellites spread widely overhead. Engineers call this dilution of precision (DOP). Adding constellations naturally improves the geometry.

Redundancy

Relying on one system means relying on one point of failure. If one constellation has a signal problem or is affected by interference in a particular area, a multi-GNSS receiver still has others to fall back on.

Does GNSS Ever Make No Difference?

To be fair, GPS alone is perfectly good for plenty of situations. If you’re driving on an open highway in rural Kansas, a GPS-only device and a multi-constellation one will usually show you in the same spot. The gap shows up in harder conditions: dense cities, parking structure entrances, mountain roads, and heavily wooded areas.

It’s also worth knowing that accuracy is shaped by more than the satellite system. Antenna quality, where the device is mounted, the chipset, and the software filtering all play a part. A well-designed GPS tracker mounted in a sensible spot can outperform a poorly installed GNSS unit.

What This Means for Car GPS Trackers

This is where the GNSS vs GPS discussion gets practical. A car tracker has two jobs: work out where the vehicle is, and send that location to you. Satellite signals take care of the first job. A cellular connection, usually 4G LTE, handles the second, delivering location updates to an app on your phone or a web dashboard.

People in the U.S. buy car trackers for all sorts of reasons. Some want to keep an eye on a new teen driver. Others want to find a stolen vehicle quickly, manage a small fleet of work vans, or check on an aging parent who still drives. In every case, a reliable position fix is what makes the tracker useful. A tracker that drifts a block away, or loses the car in a downtown parking garage entrance, is a frustrating thing to own.

When comparing devices, it helps to look at:

• Positioning technology: whether the tracker uses GPS alone or supports additional constellations.
• Update frequency: how often the location refreshes while the vehicle is moving.
• Power source: hardwired, OBD-II plug-in, or battery-powered, each with its own trade-offs between convenience and discretion.
• Alerts: features such as geofencing, speed alerts, and movement notifications.
• Subscription costs: since the cellular data has to be paid for somehow, most real-time trackers come with a monthly plan.

GPSBob’s range of car GPS trackers covers several of these approaches, so you can match a device to how you’ll actually use it rather than settling for one generic option.

Find the Right Car Tracker for Your Vehicle

Now that you know the difference between GNSS and GPS, you’re in a better position to pick a tracker that works where you drive. That might be city streets, suburban driveways, or long stretches of rural highway. GPSBob offers a range of car GPS trackers for families, small business owners, and anyone who wants peace of mind about where their vehicle is. GPSBob also has a 4.8 to 4.9 star rating from customers on Trustpilot and Google.

Frequently Asked Questions

Does it cost anything to use GPS signals?

No. GPS signals are free for anyone in the world to receive. The system is funded by U.S. taxpayers through the federal budget. Any costs you pay with a tracker cover the cellular data used to send its location to your phone, not the satellite signal itself.

What is RTK positioning?

RTK (Real-Time Kinematic) is a technique that uses a fixed base station to send real-time corrections to a GNSS receiver. It can achieve accuracy of one to two centimeters. Surveyors, precision farmers, and drone operators rely on it, but it’s rarely needed for everyday vehicle tracking.

Does bad weather affect GPS accuracy?

Ordinary rain, snow, and clouds have very little effect on GPS signals. Severe space weather, such as strong solar storms, can disturb the ionosphere and temporarily reduce accuracy. Heavy, wet foliage can weaken signals slightly, but normal weather won’t stop a receiver from working.

Is GPS jamming legal in the United States?

No. Under federal law, the FCC prohibits the sale, marketing, and use of GPS jammers in the U.S. Using one can lead to large fines and possible criminal penalties, because jammers can disrupt aviation, emergency services, and other critical systems.

Can a GNSS receiver get a location without cell service?

Yes. A GNSS receiver works out its position purely from satellite signals, so it doesn’t need cell service or internet. A real-time tracker does need a cellular connection to send that position to you. Some trackers store location data and upload it once coverage returns.