What's the Difference Between GPS and GNSS?

GPS is an American satellite navigation system with 31 satellites in orbit. GNSS is the collective term for all satellite positioning systems put together. GNSS includes GPS (USA), GLONASS (Russia, 24 satellites), Galileo (Europe, 30 satellites), BeiDou (China, 35 satellites) and several regional systems. Put simply, GPS is part of GNSS, one specific system amongst many others.

How It All Started

The US launched GPS in the late 70s for military use. Until 1994, the system was classified and ordinary people couldn't use it. When access was opened to everyone, GPS became so popular that nowadays many people call any satellite navigation simply "GPS", even when completely different systems are doing the work.

Other countries didn't want to depend solely on American technology. Russia developed GLONASS, which performs better in northern latitudes. Europeans built Galileo with a focus on civilian applications. China created BeiDou, which started as regional and later became global. There's also Japanese QZSS with 7 satellites and Indian IRNSS for South Asia.

What Multiple Systems Offer

When a device receives signals only from GPS, it can see a maximum of 31 satellites. If it supports GNSS, it can pick up signals from more than 120 satellites from different countries. This makes a real difference in cities where tall buildings block the sky, or in forests under dense tree cover. Where GPS might not work at all, GNSS will find enough satellites to determine coordinates.

Accuracy differs too. GPS in normal conditions gives an error margin of 5 to 10 metres. When a device uses several systems simultaneously, the error decreases. Professional receivers working with GNSS on multiple frequencies can determine position to within a few centimetres. This is needed for surveyors, precision agriculture and autonomous vehicles.

Where It's Used

Nearly all smartphones and car satnavs now work with GNSS, though manufacturers often just write "GPS" - it's what people are familiar with. Your phone automatically chooses which satellites to use at any moment, depending on what's receiving best.

In professional fields, the difference between GPS and GNSS is fundamental. Surveyors use multi-system receivers where every centimetre matters. In agriculture, tractors with GNSS drive across fields with 2cm accuracy, saving diesel and fertiliser. Aircraft and ships can't take risks - they need maximum signal reliability.

Earthquake monitoring stations run on GNSS round the clock, recording even millimetre shifts in the Earth's crust. Logistics firms track thousands of lorries via GNSS across the globe. On construction sites, GNSS helps monitor whether a tower block's foundation is settling or a bridge is deforming.

What It Costs

For ordinary users, the price difference is barely noticeable. Chips supporting multiple satellite systems aren't much more expensive than GPS-only chips. Professional equipment is another story though. A single geodetic GNSS receiver costs between $4,000 and $10,000, plus software licences from $400.

The main advantage of GNSS is insurance. If American satellites suddenly become unavailable (technical problem, military operation, whatever), the device switches to European or Chinese ones. With a simple GPS receiver, you're just left without navigation.