How Do GPS Trackers Work

How Do GPS Trackers Work?

How do GPS trackers work?

Wow, exciting question. Thanks for asking.

The Global Positioning System (GPS) is a satellite-based navigation system of about 30 satellites encircling the Earth that was originally designed for military use. These satellites are constantly blasting our little planet with signals.

GPS location tracking works via a process known as triangulation. Remember geometry class? It’s finally paying off.

Basically, the receiver that’s in your phone or car (or whatever you’re tracking) must receive signals from at least three of these satellites. And, based on how long the receiver takes to pick up each signal, it’s able to calculate the distance from that satellite.

Is that making sense?

In other words, the satellites are able to determine exactly where you are at all times by judging how long it takes for the signals to reach your device from the satellite. It’s a bit unsettling, isn’t it? GPS satellites are watching you!

Read on to learn the science behind how the GPS network works. This is going to be fun!

In the diagram below, you can see firsthand how this works, with each circle’s radius denoting its distance from a satellite. The intersection of these circles reveals the precise location of the receiver.

How Do GPS Trackers Work?: The Science Behind GPS Tracking

The 3 Elements Of GPS Tracking

1. Satellites

Satellites are the main component of GPS tracking.

GPS tracking relies on a constellation of satellites that form the Global Positioning System (GPS). These satellites orbit the Earth at an altitude of approximately 20,200 kilometers, and they’re constantly transmitting signals that contain positioning and time data. 

The GPS consists of at least 24 operational satellites. This ensures that GPS receivers can access signals from multiple satellites simultaneously, enabling more accurate positioning.

5 Fun Facts On Satellites

• Minimum Coverage: The GPS system requires a minimum of 24 operational satellites to ensure that at least four satellites are visible from any point on Earth.
• Orbits: GPS satellites orbit the Earth at an altitude of about 20,200 kilometers (12,550 miles) and complete two full orbits per day.
• Atomic Clocks: Each GPS satellite is equipped with multiple atomic clocks that provide highly accurate time measurements. These time measurements are necessary for determining precise locations.
• Signal Transmission: GPS satellites continuously transmit radio signals containing their position and time data, which are then picked up by GPS receivers on Earth to calculate their exact location. They’re basically broadcasting their position and the current time 24/7 so that receivers can pick them.
• Satellite Replacement: GPS satellites have a lifespan of about 10 to 15 years. To maintain the system’s functionality, the network replaces older satellites with newer, more advanced ones.

2. Ground Control

Ground control monitors and tracks satellite signals at all times to make sure everything is functioning properly through a network of monitoring and control stations. This network of stations makes sure the network of satellites is orbiting properly and transmitting signals all day.

The ground control stations also analyze satellite data and transmit any necessary corrections back to the satellites, which then incorporate these corrections into the signals they broadcast. This continuous process of monitoring and adjusting guarantees that the information provided to GPS receivers remains accurate and reliable.

5 Fun Facts On Ground Control Stations

• They’re Essential: Ground stations monitor satellite positions and provide necessary updates. Without them, the GPS system would fail to work.
• Global Coverage: Ground control stations, like the master control station in Colorado and international sites ensure that the GPS system covers the entire globe.
• Space Weather Monitoring: Ground stations also monitor space weather to assess its impact on GPS signal quality and accuracy. If there’s inclement weather up there, it helps to know about it ASAP and prepare.
• Military Origins: The ground control segment of the GPS system was originally designed for military purposes, but its applications have expanded to include civilian use.
• International Cooperation: The ground control infrastructure is not limited to the U.S. GPS system. Other global navigation satellite systems, such as Russia’s GLONASS and Europe’s Galileo, also rely on ground stations to maintain their respective constellations.

3. Receivers

The third key element in GPS tracking is the receiver. 

GPS receivers collect the signals transmitted by GPS satellites. You can find them in pretty much any device these days, especially phones and GPS tracking devices. 

They pick up signals from multiple satellites and calculate the time it takes for each signal to travel from the satellite to the receiver in order to determine its precise location using a process called trilateration. This location data can then be used for various purposes, including navigation, asset tracking, and fleet management.

5 Fun Facts On GPS Receivers

• First Handheld GPS: The first handheld GPS receiver, the Magellan NAV 1000, hit the market in 1989, paving the way for portable navigation devices.
• GPS In Smartphones: Modern smartphones have built-in GPS receivers that make location-based services and apps accessible to millions of users worldwide.
• Animal Tracking: GPS receivers are used in wildlife conservation efforts to track animal movements, study migration patterns, and help protect endangered species.
• Geocaching: Geocaching is a popular outdoor activity that relies on GPS receivers to locate hidden containers, or “geocaches”. There’s now a massive worldwide treasure-hunting community due to receiver technology.
• GPS Art: Don’t even ask me what this is or why people do it. But GPS receivers enable “GPS drawing” or “GPS art,” where users create digital images by recording their movements with a GPS receiver and then display the tracked paths on a map. People need to get real jobs.

The Process of Determining Location

Triangulation: A GPS Overview

Triangulation is the mathematical foundation of GPS tracking.

Let’s take a look into how it works...

The satellite network, specifically the space segment of the GPS system, consists of a constellation of satellites strategically positioned around Earth.

When you use a GPS-enabled device to find your location, you must first establish a connection with these satellites. 

Your device “listens” for radio signals transmitted by the satellite network. 

These radio signals contain unique PRN codes identifying each satellite and a navigation message providing essential data about the satellite’s health, current time, and predicted orbit.

When your device receives these signals, it uses its GNSS receiver to calculate the time of flight—the duration the signal took to travel from the satellite to the receiver. Once your device receives this signal, it now has a range of possible positions. It just needs to figure out which one is correct…

To accurately pinpoint your location, GPS uses signals from multiple satellites. A single satellite only gives a broad area where you might be. With two satellites, this area narrows to a circle. With three satellites, you get much closer, narrowing it down to two possible points on Earth. Usually, only one of these points makes sense, as the other might be somewhere impractical—like high in the atmosphere or deep underground.

For precise triangulation, you need clear signals from several satellites with minimal interference. Clear lines of sight to satellites improve accuracy, ensuring the GPS can lock onto your exact location.

Why Three Satellite Signals Are Essential

The reason you need three satellites is that only 1 or 2 is not enough to find your precise location. 1 satellite would only create a general vicinity of where you might be. 2 create a large circle of where you might be. But with 3, GPS can pinpoint your exact location.

With three satellite signals, that overlap narrows down to just two points. Usually, one of these points doesn’t make sense (like in outer space), so the other one is your real location.

The Fourth Satellite and Improved Accuracy

So, how accurate is GPS, really? 

With three satellites, GPS can give you your latitude and longitude. But when a fourth satellite comes into play, it adds altitude info, making your location even more precise by fixing any clock errors in the receiver. The more satellites your GPS connects to, the sharper your location data gets.

GPS accuracy also depends on satellite clocks staying in sync, and ground control stations constantly monitoring and adjusting satellite positions to keep everything on track. With new satellites and better tech coming, GPS will only get more accurate and reliable, giving us even better tracking in the future.

Time-Based Calculations in GPS Technology

Using GPS tracking devices might seem complex, but it’s really just simple physics…that I’m sure you love (not me, I have friends).

GPS - and other similar devices like Bluetooth trackers - measures the time a signal takes to travel. 

Still with me…?

Imagine you send a beam of light to a mirror and measure the time it takes to return. Knowing light’s speed, you can calculate the mirror’s distance. GPS tracking systems use a similar approach, but instead of mirrors, they communicate with satellite systems.

Here’s how it works for GPS: When a satellite sends a signal to your GPS device, the device notes the exact moment it receives it. Since the signal travels at the speed of light, by calculating the time taken, the device determines how far away the satellite is. This is crucial for vehicle GPS trackers to provide precise location data.

For fleet tracking, such time-based calculations ensure optimized routing and enhance operational efficiency. In the world of asset trackers or vehicle tracking, these calculations are indispensable. They help reduce fuel costs and ensure fleet safety by providing real-time data.

Accuracy of GPS Trackers

GPS accuracy matters a lot since it’s key to both everyday and military uses. For civilian purposes—like tracking people, cars, or lost items—GPS accuracy is usually within a few meters to tens of meters. That’s plenty for things like navigating city streets or keeping tabs on loved ones…or catching your cheating dog of a boyfriend at his new girl’s place when he says he’s “working late”.

For the military, GPS needs to be way more precise, often aiming for accuracy within centimeters. The military depends on this level of detail for positioning troops, equipment, and guided weapons. In these cases, pinpoint accuracy is essential for successful missions and staying a step ahead.

Signal Multipath and Its Effects

Signal Multipath can seriously mess with GPS accuracy—it’s like an echo for radio waves. 

When satellites send signals to your GPS device, they ideally reach it directly. But in real life, things like tall buildings, hills, or dense trees can cause signals to bounce around before reaching your tracker. This bouncing creates "multipaths," or extra routes for the signal.

When these delayed signals hit your GPS, they can throw off your location because the GPS assumes a direct path. To fix this, GPS receivers use special antennas and algorithms to filter out these extra signals, giving you a more accurate position.

Enhancing Accuracy With DGPS

DGPS is a sophisticated technique that employs additional ground-based reference stations to address and correct any potential errors in GPS data.

Here’s how DGPS works: These reference stations are strategically positioned across a given area, often spaced tens of kilometers apart. They receive the same GPS signals as your tracker device and calculate the precise difference between their known locations and the GPS-derived positions. This differential information is then transmitted to GPS users, including your tracker device, in real-time.

When your tracker device receives these differential corrections, it can adjust its calculations accordingly. This correction accounts for any errors caused by atmospheric conditions, signal multipath, or other factors, significantly enhancing its accuracy. For businesses reliant on fleet tracking, DGPS can result in enhanced operational efficiency, improved fleet safety, and optimized routing, ultimately leading to cost savings and improved services.

In critical applications like medical alerts to ensure the safety of loved ones, this heightened accuracy can be a lifeline. It means that the global navigation satellite systems you depend on are as precise and reliable as possible, ensuring that your GPS tracker device provides accurate information when it’s needed most.

Frequently Asked Questions