GNSS vs GPS: what is the difference and why it matters for surveying
Key takeaways
- GPS is a single satellite system run by the United States; GNSS covers every global and regional satellite navigation system.
- Four global constellations operate today: GPS, GLONASS, Galileo and BeiDou, supported by regional systems such as QZSS and NavIC.
- All GNSS positioning works by measuring distances to at least four satellites and solving for position and receiver clock error.
- Multi-constellation, multi-frequency GNSS receivers give more satellites and better geometry, which speeds up RTK fixes near trees and buildings.
- For surveying and machine guidance, the real accuracy jump comes from RTK corrections, not from the choice between GPS and GNSS alone.
GNSS vs GPS: the short answer
The GNSS vs GPS question is really about a family and one of its members. GPS, the Global Positioning System, is the American satellite navigation system. GNSS, short for global navigation satellite system, is the generic term for every satellite system that broadcasts positioning and timing signals.
In everyday speech people say "GPS" for any satellite positioning, much as they use a brand name for a whole product category. In surveying, agriculture and engineering the distinction matters, because a receiver that tracks only GPS sees far fewer satellites than one that tracks all constellations.
So every GPS receiver is a GNSS receiver, but not every GNSS receiver is limited to GPS. Modern survey equipment is almost always multi-GNSS.
What is the global positioning system (GPS)?
The global positioning system is a satellite navigation system owned by the United States government and operated by the US Space Force. It was the first of today's GNSS constellations to reach full worldwide operation and remains the most widely used.
GPS satellites orbit at about 20,200 km altitude in medium Earth orbit, arranged in six orbital planes. The system was designed around a baseline of 24 satellites, and in practice around 30 or more operational satellites are usually in orbit, so how many satellites make up the GPS system at any moment varies slightly as satellites are launched and retired.
The first GPS satellite was launched in 1978, and full operational capability was declared in 1995. GPS broadcasts on several frequencies, called bands: L1, L2 and the newer L5. Civilian receivers once used only L1; modern survey receivers track all three.
What is GNSS and which GNSS systems exist?
GNSS is any constellation of satellites that provides positioning, navigation and timing from space. Four systems give global coverage, and two regional systems add satellites over specific areas.
| System | Operator | Coverage | Main civil bands (typical) |
|---|---|---|---|
| GPS | United States | Global | L1, L2, L5 |
| GLONASS | Russia | Global | L1, L2 (plus newer L3) |
| Galileo | European Union | Global | E1, E5a, E5b, E6 |
| BeiDou (BDS) | China | Global | B1I, B1C, B2a, B2b, B3I |
| QZSS | Japan | Asia-Oceania | L1, L2, L5, L6 |
| NavIC | India | India and surroundings | L5, S-band |
Satellite-based augmentation systems (SBAS) add correction signals over continents but do not provide their own independent positioning. The Galileo GNSS system and BeiDou are now fully operational, which is why a modern receiver in open sky can often track several dozen satellites at once instead of around eight to twelve GPS satellites.
How do GPS systems and GNSS work?
All GNSS systems work the same way: each satellite broadcasts its precise orbit and a time signal, and the receiver measures how long each signal took to arrive. Multiplying travel time by the speed of light gives a range to each satellite.
- The receiver locks onto signals from visible satellites and decodes their orbit data (ephemeris).
- It measures the signal travel time, giving a "pseudorange" to each satellite.
- Because the receiver's own clock is not perfect, it solves for four unknowns: latitude, longitude, height and clock error.
- This needs at least four satellites; more satellites improve reliability and geometry.
- The receiver outputs a position, typically accurate to a few metres in standalone mode.
Errors come from the ionosphere, troposphere, satellite orbit and clock errors, multipath reflections and receiver noise. Using two or more frequencies lets the receiver remove most ionospheric delay, which is why multi-band GNSS signals matter for precision work. Our article on how accurate GPS is, from metres to millimetres breaks down each error source.
Difference between GPS and GNSS in surveying
For global positioning system work in surveying, the practical difference between GPS and GNSS is availability. More satellites mean more fixed solutions in places where a GPS-only receiver would struggle.
| Factor | GPS-only receiver | Multi-GNSS receiver |
|---|---|---|
| Satellites in view (open sky) | Typically 8–12 | Often 30 or more |
| Near trees, buildings, pits | Frequent loss of fix | Fix held more often |
| RTK initialisation | Slower, less reliable | Faster, more reliable |
| Satellite geometry (DOP) | Weaker | Stronger |
| Single-system outage risk | Dependent on one operator | Redundant across systems |
Precision on a good day in open sky is similar; the gain is in productivity and robustness. A GNSS rover on a road corridor, a mine or an urban block simply gets more usable points per day. The antenna also matters: see our guide to GNSS antennas and L1/L2/L5 bands.
How does RTK GPS work with GNSS?
GNSS RTK (real-time kinematic) is the technique that turns metre-level GNSS into centimetre-level positioning. It uses the carrier phase of the satellite signals and corrections from a nearby reference station.
A base station on a known point, or a CORS network, measures the same satellites as the rover and sends corrections, usually in RTCM format by radio or over the internet with NTRIP. The rover resolves the whole number of carrier wavelengths (ambiguity resolution) and achieves typical horizontal accuracy of about 1 cm plus 1 ppm of the baseline length.
An RTK GNSS receiver benefits directly from multiple constellations, because ambiguity resolution needs many clean signals. For the full explanation, read what RTK GPS is and how real-time kinematic surveying works.
Types of GPS systems and GNSS equipment for professionals
GNSS equipment ranges from consumer chips to geodetic reference stations. The type you need depends on the accuracy your work requires.
- Navigation and consumer receivers: phones, car units and handheld devices with metre-level accuracy.
- GIS mapping receivers: sub-metre to decimetre accuracy for asset inventories.
- GNSS survey equipment: RTK rovers and bases with centimetre accuracy for topography, stakeout and control.
- Ag GPS systems and machine guidance: smart antennas on tractors and heavy equipment for guidance and auto-steering.
- Reference stations: fixed GNSS stations and geodetic antennas that feed CORS networks.
Mars Geosystems products illustrate the range. The E1 GNSS RTK receiver uses a 1408-channel full-constellation engine and works as radio base, radio rover or NTRIP rover. The S20 GNSS smart antenna for vehicles tracks GPS, GLONASS, Galileo, BeiDou, QZSS, NavIC and SBAS. For reference stations, the SA102 geodetic antenna tracks GPS, BDS, GLONASS, Galileo, QZSS, SBAS and L-Band signals.
Choosing a GNSS receiver for surveying
When choosing a GNSS receiver for surveying, look beyond the "GPS" label and check constellations, bands and correction options. These decide real-world performance far more than headline accuracy numbers.
- Full constellation tracking (GPS, GLONASS, Galileo, BeiDou, plus QZSS where relevant).
- Multi-frequency signals, including L5/E5a/B2a, for faster fixes and ionospheric correction.
- Correction links: UHF radio for base-rover work and NTRIP for CORS networks.
- IMU tilt compensation, ruggedness (IP67 or IP68) and battery life for long field days.
Our guide on how to choose a GNSS RTK receiver walks through each specification. When you are ready to compare configurations for your projects or dealer network, request a quote; Mars Geosystems supplies from one unit with OEM options.
Frequently asked questions
What is the difference between GPS and GNSS?
GPS is a single satellite navigation system operated by the United States. GNSS is the general term covering all satellite navigation systems, including GPS, GLONASS, Galileo, BeiDou and regional systems such as QZSS and NavIC. A GNSS receiver can use several of these at once, while a GPS receiver uses only American satellites.
Is GNSS more accurate than GPS?
In open sky, standalone accuracy is similar, typically a few metres. The advantage of GNSS is that more satellites improve geometry and availability, so the receiver holds accurate solutions near trees, buildings and slopes. With RTK corrections, a multi-GNSS receiver reaches centimetre accuracy more quickly and more reliably than a GPS-only receiver.
How many satellites make up the GPS system?
GPS was designed with a baseline constellation of 24 satellites in six orbital planes at about 20,200 km altitude. In practice the operator usually keeps around 30 or more operational satellites in orbit, so the exact number varies over time as new satellites launch and older ones are retired.
What is a GNSS receiver?
A GNSS receiver is a device that tracks signals from navigation satellites and calculates its position, velocity and time. Survey-grade GNSS receivers track multiple constellations and frequencies and accept RTK corrections, giving centimetre accuracy. They are used as rovers to measure points and as base stations that send corrections to rovers.
What are GNSS bands?
GNSS bands are the radio frequencies satellites use to broadcast signals, such as GPS L1, L2 and L5, Galileo E1, E5a, E5b and E6, and BeiDou B1, B2 and B3. Tracking more than one band lets a receiver cancel most ionospheric delay and resolve RTK ambiguities faster, which improves precision and reliability.
Do I need a GNSS receiver or a GPS receiver for surveying?
For professional surveying you should choose a multi-constellation, multi-frequency GNSS receiver with RTK capability. GPS-only receivers are now uncommon in survey equipment and lose fix more easily under obstructions. Check that the receiver supports GPS, GLONASS, Galileo and BeiDou, plus your preferred correction method, such as UHF radio or NTRIP.
Need equipment for this work?
Tell us the job, the country and the quantity. An engineer replies with a configuration and price within one business day. MOQ is one unit; OEM is available.
