Satellite GPS is the foundation of modern tracking. In this guide we explain what it is, how it works technically, the difference between calculating a position and transmitting it, and why it’s key to locating vehicles and assets anywhere — even where there’s no cellular signal.
What is GPS?
GPS (Global Positioning System) is a satellite network, originally operated by the United States, that lets a receiving device calculate its exact location on Earth from signals it receives from at least four satellites simultaneously. Technically, GPS is one of several satellite navigation constellations that exist — the broader term is GNSS (Global Navigation Satellite System), which also includes GLONASS (Russia), Galileo (European Union), and BeiDou (China). Many modern trackers are multi-constellation: they combine GPS and GLONASS to get a faster, more accurate position fix, something you’ll see mentioned in the specs of several devices we distribute.
How a GPS device calculates its position
Each satellite constantly transmits its exact position and the exact time of that transmission. The GPS receiver measures how long the signal took to arrive from each satellite and, from that time difference, calculates the distance to each one. With the distance to at least four satellites, the receiver can triangulate (more precisely, trilaterate) its exact position in three dimensions: latitude, longitude, and altitude. The more satellites the receiver “sees,” the more accurate the calculated position — which is why GPS performs worse indoors, between tall buildings, or inside tunnels, where the line of sight to the sky is blocked.
Satellite GPS vs. cellular connectivity: two different things
Here’s the point that causes the most confusion: GPS calculates the position, but doesn’t send it anywhere on its own. For a fleet manager to see that position on a map, the device needs to transmit the data — and that’s where connectivity comes in, a completely separate system from GPS:
- Cellular transmission (SIM): the most common. The device sends its position over the mobile network (2G/3G/4G), just like a phone. It works well where there’s cellular coverage, but is lost in rural areas, remote corridors, or border crossings without nearby towers.
- Backup satellite transmission: equipment such as the ERM StarLink line uses an additional satellite link to keep reporting position even without cellular coverage — critical for long-distance transport through rural corridors.
A device can calculate its position perfectly with GPS and still fail to report it to any platform if it loses its transmission connection — which is why the choice of connectivity type matters as much as the choice of tracker itself.
How accurate is it
Under normal conditions (clear sky, no obstructions), a modern GPS receiver locates within a margin of a few meters. Factors that reduce accuracy include: tall buildings that reflect the signal (the “urban canyon” effect), roofs and metal structures, and extreme weather. Multi-constellation equipment (GPS + GLONASS) mitigates part of this problem by having more satellites available to calculate the position.
Applications
- Vehicle tracking: cars, motorcycles, trucks, and entire fleets.
- Asset and container tracking: cargo that doesn’t always travel inside its own vehicle.
- Personal and pet tracking: compact personal-tracking devices.
- IoT and telematics solutions: combining position with sensor data (fuel, temperature, driving behavior).
Why choose NuMar?
We’re authorized distributors of leading satellite GPS and telematics brands — Teltonika, ERM Advanced Telematics, Cellocator, Ruptela, and more — with solutions adapted to Colombia and all of the Americas, technical guidance to choose the right equipment for your operation, and coordinated installation.
Frequently asked questions
Does GPS work without internet? It calculates position without needing internet; only to transmit it to a platform does it need a cellular network or a satellite link.
How accurate is it? Under normal conditions, it locates within a margin of a few meters; roofs, tall buildings, or extreme weather can reduce that accuracy.
What’s the difference between GPS and GNSS? GPS is the U.S. constellation; GNSS is the general term that includes GPS and other constellations such as GLONASS, Galileo, and BeiDou. Many modern devices combine several.
Why does my tracker sometimes not report its position? It’s almost always a transmission issue (no cellular signal), not a GPS calculation issue — which is why equipment with satellite backup is preferable in rural areas.
Do I need a data plan for it to work? Yes, if transmission is cellular you need an active SIM; see our M2M SIM card plans.
See our vehicle tracking solutions or contact us for a free consultation.