How does GPS work?
27 Jan 2010 Jason 10
GPS is a complicated subject so let’s get right back to the basics of GPS; what is it and how it works. As an example in demonstrating how GPS technology is being used, we will look at how it is helping the ground transportation sector to route vehicles more efficiently.
Making an informed choice about GPS systems
If you’re looking to invest in a GPS system you don’t necessarily need to know exactly how it works, just like you don’t have to know how a car works to drive one. You just get in and shift it into drive.
But understanding how GPS works can help you to make a better decision when it comes to choosing the best GPS system. Unfortunately many people who buy GPS systems don’t know much about them. They end up making the mistake of getting something that is overkill, with features they’ll never need and a price tag to match. In some ways it’s like buying a car without knowing that the more liters a vehicle’s engine has affects its power and fuel consumption – if you didn’t need the extra power why pay for a fuel guzzler? Then again buying a Prius when you need to tow a 240-foot super-yacht could be disastrous.
In a similar way, different GPS systems work in different ways, some are better suited to specific environments, some are free, and others have ongoing charges. By understanding some of the science behind GPS and how it works you can make sure you get the best GPS navigation system for your needs, or the needs of your business.
What is GPS?
GPS stands for Global Positioning System and is a network that is made up of three main segments:
- Space segment – 24 satellites orbit the earth twice a day, traveling at over 7,000 mph. They are solar powered but have battery backup for when they are in the earth’s shadow. They are positioned so that at any given time there are at least 4 satellites ‘visible’ from any point on earth.
- Control segment – A master control station (located in Colorado Springs), unmanned monitor stations and ground antennas work together to make sure the satellites are working correctly and the information they beam down to earth is accurate.
- User segment – This is where you, the user comes into the picture. The user segment is made up of GPS receivers, which is any device built to receive signals from a GPS satellite. This can include mobile phones, laptops, in-car navigation devices and hand-held tracking units.
How does GPS work?
So how do a bunch of satellites buzzing around in space help us down here on earth? Watch the video below to get some background on how GPS got started and how it works.
If you’re in a hurry here are the main points
- GPS is a system that uses radio frequencies to find your exact location
- Developed by the military to know the location and movement of planes, ships and soldiers
- Accurate to meters, with newer satellites offering even greater accuracy
- Now used in cars, planes, boats, laptop computers and construction equipment
- When a GPS receiver is switched on it ‘listens’ (by receiving radio waves sent from space) to find the four nearest satellites to help calculate its current location
- The quartz clock in your GPS receiver continually updates to stay in sync with the very accurate atomic clocks used by the GPS satellites
- A GPS system can tell you how far you’ve traveled, your current direction, your speed and ETA
- The ways in which GPS is being used are constantly growing as people think of new ways to apply GPS technology. For example, seismologists use GPS units to detect plate movement.
In the video it’s mentioned that satellites determine position using trilateration. It’s not an easy concept to explain with words so have a look at this animated sequence that shows how several satellites work together to provide an accurate intersection point, or location.
Credit: Animation courtesy of howstuffworks.com
Now that we have an overview of how these satellites are used to locate objects on earth, we can start to understand the many uses of GPS. One of these uses is GPS navigation systems as used for ground transportation (also referred to as AVL or Automatic Vehicle Location) and in our next post we’ll look at the two main variations of GPS navigation systems – connected and non-connected.
Knowing the difference can help save you money and you’ll get the best GPS system for your needs!