If you love spending time getting off the beaten track, searching for great hunting spots, unfinished rivers, or push the boundaries for new trails or rocks to climb, having a GPS with you is key. You can navigate your way around, always knowing where you are, where you’re going, and you can mark any awesome finds plus save your routes so you can find them again on your next adventure.
While we know what GPS’ can do, how do they actually work? Having a greater understanding of your GPS system will enable you to use them more effectively, so join me as we discuss – GPS: Your Questions Answered.
Let’s start right at the beginning and look at what GPS actually stands for. GPS stands for, Global Positioning System, which I’m sure a lot of you managed to guess through common sense. It lets you know where you are and where you’re going, everywhere on planet earth.
GPS was invented in 1973 by the US Department of Defense. It was originally only allowed to be used by the US military but in the 1980s, US President Ronald Reagan changed things and made it accessible to the public.
The first GPS satellite was launched in 1978 and by 1993 there were 24 satellites in operation. But the US wasn’t the only one to create a GPS network as the Russians, Europeans, and Chinese were not far behind.
A GPS network is a three-part system consisting of satellites, ground stations, and receivers that you’ll find in your GPS device, car, or mobile phone. Imagine the satellites like stars, which we used to navigate from the in the old days. We always know where the satellites are supposed to be, just like the stars, and therefore can navigate from them.
As the satellites orbit the earth some 12,000 miles up, the ground stations control and monitor them in order to determine their locations – where they were, where they are, and where they are going to be.
Once you turn on your GPS system, the receiver is constantly looking for signals from the satellites orbiting in the earth. Each satellite carries an atomic clock which provides an incredibly accurate time that is used to know the satellite’s exact location, along with the ground stations.
The satellites send out a code containing the time information so that your receiver always knows when the signal was broadcast.
Once your GPS system is connected to a satellite, it uses the data to work out latitude, longitude, altitude, and time, and once connected to 4 or more satellites, it will triangulate your exact location as each satellite sends a different bit of data via code to the receiver.
A standard GPS device will know your location to within 5-10 meters or so and a high-tech one will give you a location accuracy of up to less than an inch, all from satellites 12,000 miles away. Pretty amazing right?!
For us regular people, GPS has made a huge difference in our lives. Do you remember using paper maps to get you from A to B on a long drive or a commute through a busy city? I remember it being a nightmare, usually ending up with some kind of navigation argument between the driver and the map reader.
Even finding a shop in downtown New York or trying to get off the bus at the right stop in a new city was tricky. You’d spend ages going down the wrong street, getting off the bus a little early and having to walk, or missing your stop by miles.
Nowadays, your phone and a map app, I use GoogleMaps, takes you right to where you want to be, and on the most efficient route, even avoiding traffic. But, GPS is just there to make our daily lives easier and more efficient, it has far more important uses.
On average, there are around 10,000 planes in the sky at once, all using GPS systems to navigate, and to also avoid each other so that no crashes happen. The same goes for offshore fishing or shipping vessels. They are crossing the oceans and spending weeks, even years at sea, and without a GPS, they’d be relying on stars and sextants to get them from A to B, making it far less efficient, and causing far more random accidents too.
GPS is also used in science to monitor natural disasters like earthquakes, volcanic eruptions, and more. Scientists even use GPS to analyze our atmosphere as certain substances in the air delay GPS signals and by monitoring this, scientists can make new discoveries and use it as a warning system by calculating how much snow or rain might fall in a particular area and warning of flash floods.
So, GPS is important, in almost every aspect of the world from our daily lives, to monitoring the health of the planet, and ensuring that global travel and shipping, keeps ticking along safely.
There are currently four global GPS systems in orbit and each one is associated with a different country. There is the GPS network (USA), the GLONASS network (Russia), Galileo network (Europe), and finally the BeiDou network (China). In addition to these global networks, there are two regional networks, one in Japan called QZSS and one in India called IRNSS or NavIC.
Currently, there are 134 satellites orbiting the heart across all the systems mentioned above. The US’ GPS system has a total of 31, Russia GLONASS has 24, Europe’s Galileo has 24, and China’s BeiDou has a whopping 55 satellites in orbit.
GPS satellites fly in medium earth orbit (MEO) at some 12,000 miles above the earth. Each satellite will orbit the earth twice a day. They are not all in the same orbit though, and each one will have its own orbital direction around the earth to provide great coverage and thus better location accuracy for our GPS devices.
Satellites transmit continuously, there is no break whatsoever. They send signals via radio waves to your receiver and once connected, your receiver and remain connected, consistently getting updated data to mark your global position.
This is how a GPS is able to track your movements, which is super important when it comes to navigation. By staying constantly connected to the satellites it can work out where you are, where you’re going, and thus give you your direction, and remember where you have been in order to save routes.
When you’re using a GPS device it will tell you your location on earth by giving you your latitude and longitude in both degrees and minutes. There are 360 degrees around the earth, like a circle, and each degree is made up of 60 minutes.
The symbol for degrees is °, and the symbol for minutes is ‘, and your GPS coordinates will look a bit like this – 41°24’N 2°10’E. Now that we understand how degrees and minutes work, what do the N (North), S (South), E (East), and W (west) parts refer to? It’s all about latitude and longitude.
Latitude is measured from the Equator which is set at 0°. The equator is not in either the northern or southern hemispheres. If a location is in the Southern Hemisphere, your latitude coordinate will read with the letter S before or after the numbers. If your location is in the Northern Hemisphere, your latitude coordinate will read with the letter N before or after the numbers.
On occasion, no letter is given with the coordinate and anything in the Northern Hemisphere will have positive numbers, and any coordinate in the Southern Hemisphere will have negative numbers. So -6° means 6 degrees south of the equator, and 6° means 6 degrees north of the equator.
Longitude is measured from the Prime or Greenwich Meridian which is a line running north to south down the entire planet which passes through the Royal Observatory, Greenwich, in London, England. It acts as the equator does when it comes to latitude.
Unlike measuring latitude, you don’t express longitude by hemispheres east or west, but by measuring the direction towards the Prime Meridian from your location. It’s much simpler than it sounds, promise.
If you’re measuring a location East of Prime Meridian, you would use the letter E. If measuring West of prime meridian you would use the letter W. So if you’re 300° East of Prime Meridian, you would also be 60° West of Prime Merdian, as 360° is the full circle or orbit of the earth.
Sometimes, like with latitude, the letters are left out and positive and negative values are used instead. Negative values = West, and positive values = East. So 270° (East) is the same longitude as -90° (West).
Now that you understand both longitude and latitude separately, it’s time to think about them together. Imagine latitude first, and say it gives you 6°S – meaning you are 6° south of the equator. But you have no idea where you are east to west and could be anywhere from Indonesia to Columbia.
Now add a longitude of say 106° E, giving you 6° S, 106° E, which places you in the capital of Indonesia, Jakarta.
Nowadays yes, but you’ll need to read the specs of the GPS device to make sure this is possible. Some will come with access only to say the GPS network, others will be able to use GPS and GLONASS, and some will even connect to three networks such as GPS, GLONASS, and Galileo networks.
Yes. The more satellites available for your GPS device to connect to, the better your global coverage will be and the better your location accuracy. If your GPS is connected to just 4 satellites (the minimum), you’ll have location accuracy down to around 10 meters and your tracking will be ok. If it can connect to say 8, everything improves including accuracy and location tracking.
Another advantage of being able to connect to multiple networks is how quickly your GPS device will pinpoint your location once turned on. When you turn it on, it has to find and connect to a minimum of 4 satellites, if there are more to choose from, the connection time reduces it’ll pinpoint your location much faster.
Yes and this is defined by the number of satellites the network has in orbit. If you can only use one network with your device, say the GLONASS network, you’ll only have 24 satellites to choose from, and a lot of them will be on the side of the planet. Whereas with the GPS network, you’ll have 31 satellites to connect to, increasing your chances of picking up 4 or more satellites and faster too. But, it’s always best to have access to multiple networks as mentioned above.
The GPS in your cell phone works just like any other GPS unit out there. Every cell phone with GPS has GPS receivers inside it and you can use GPS in your Apps without any data or cellular connection. This means you can take your phone anywhere and use it as a GPS without having to worry that it might not work just because you have no data or cellular signal.
Next time you’re on a flight, open up Google Maps with your phone in Airplane mode, most of the time you’ll be able to track exactly where you’re going.
There are often times when your GPS will lose a signal and stop tracking you or showing your current location, but why does this happen? Well, there are a number of reasons, all of which we will discuss below and they are either due to signal jamming, loss, or blockage.
As I mentioned a few times above, your GPS device needs to be connected to at least 4 satellites in order to give you an accurate location. Satellites are always moving and if your device is connected to 4, and one of the 4 moves around the earth and drops its connection, your location will be offline until the GPS device finds another satellite to replace it with.
Nowadays this issue is quite rare thanks to the different networks working together and the number of satellites orbiting the earth, but if it does happen to you, it shouldn’t take more than 5-10 minutes to get reconnected.
If the signals from the satellites can not reach your GPS device, then you won’t be able to get an accurate location. Things like tall buildings, mountains, trees, and even bad weather can interfere with satellite signals and cause your GPS device to drop its connection.
It usually doesn’t last very long, so if it does happen, don’t panic. If you move around a bit, your connection will usually be restored quite quickly.
Satellite signals come from the sky to your GPS device. If you’re inside your house or underground, the signals will be blocked by the concrete and steel, and you’ll have to go outside in order to get a connection.
Solar storms do not happen often but when they do, they have the ability to move, block, and even break the satellites orbiting the earth, on which your GPS device relies to give you a location.
Like all mechanical things, satellites also require some maintenance now and then, plus they are quite often re-maneuvered within the network. This can happen at any time without warning, and if you’re connected to a satellite that is then re-maneuvered or is having some maintenance done, you’re going to lose signal and have to wait for your GPS device to connect to another satellite to restore your location services.
Equatorial Plasma Irregularities, also known as EPIs, can block the radio waves being sent down to your GPS device. This usually only happens in places near to the planet’s magnetic equator and at low altitudes too, and should not affect you very often, unless of course, you live in such an area.
The final thing that can go wrong is an internal problem with your actual GPS device. The issue will most likely be with the antenna that is receiving the signals from the satellite or it could be a problem with the processor that computes all the data to give you a location. If this happens, you should contact your GPS manufacture and get a warranty fix or replacement.
If it happens while you’re in the sticks, then hopefully you remember a map and compass, as you always should. GPS’ can break/fail, so don’t rely on them solely, and always carry the old school manual backup system of a compass and a map.
There you have it, pretty much everything you need to know about how a GPS works and why it might lose a signal in some cases. They are pretty amazing devices and have become part of our day to day, but don’t fully rely on them when going off into the wilderness. They can break, run out of battery, be destroyed by being dropped in a puddle, and more, so always carry a map and compass too.
Roger is a little obsessed with travel. He has been to over 40 countries, broken 3 suitcases and owned over 10 backpacks in 12 months. What he doesn't know about travel, ain't worth knowing!