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I bought my first GPS watch and I wondered if I can use it without the internet. I researched how a GPS works and if it would work properly without the internet and here’s what I found.
GPS running watches don’t need internet to determine your location. It uses satellites that send a signal to your GPS watch and determines the distance between the satellite and the receiver. Having 4 or more satellites that send signals to a receiver triangulates your position and pinpoints your location.
Ahead, we will go a little deeper on how GPS running watches work and what are some factors that could affect their accuracy.
How Does a GPS Watch Work?
In order for your running watch to work, it needs a satellite and a receiver.
GPS is the most popular satellite or Global Navigation Satellite System (GNSS) but it isn’t the only satellite available. Navstar GPS (or simply GPS) is the satellite of the United States of America.
Here’s a list of other satellites provided by other countries.
| GNSS | Owner | Accuracy | No. of Satellites |
|---|---|---|---|
| GPS | USA | 5m to 1m | 32 |
| GLONASS | Russia | 7m | 26 |
| Galileo | EU | 7-1m | 26 to 30 |
| BeiDou | China | 10-2m | 15 to 35 |
| IRNSS | India | 20m | 7 to 11 |
| QZSS | Japan | 2-3m | 4 |
You might have come across these satellites, the GLONASS by Russia and Galileo by EU which are common in Garmin devices like the Garmin Forerunner 945 and the Garmin Fenix 6.
Your GPS running watch works by pinpointing your location this way:
- Satellites send the signal to your watch (the GPS receiver)
- Your watch can tell the exact time the signal is released and the time the signal is received
- By calculating the time it took for the signal to travel and the speed of the signal, it can determine your distance
- But one satellite can’t determine your location, so it uses at least 4 satellites to triangulate your position and tell your exact location
Theoretically, the more satellites your watch can connect to, the better it is at providing accurate data.
But there are factors that could affect the accuracy of these watches. Let’s talk about them in the next part of this article.
What Could Affect The Accuracy Of GPS Running Watches?
There are three factors that could affect the accuracy of your running watch.
- Multipath
- The atmosphere
- Body position
Multipath is when the signal bounces from something before it goes into your watch (the receiver). This ‘something’ could be a building, trees, or any interference.
The dense atmosphere could also affect the signal slightly.
Lastly, your body position when you receive the signal. When you’re running your body can block the signal of one satellite during an arm swing.
But don’t get discouraged from buying a GPS watch. These factors only account for 0.2 to 0.6m of inaccuracy. And even that is mitigated by the technology in your watch.
By using complex algorithms and tech developments, your watch can identify if the signal came directly from the satellite or from a bounce and disregards the data that came from the latter.
In addition, having a multi-GNSS watch (meaning, it connects to multiple satellite systems) allows it to gather data from multiple sources making it more accurate.
That’s why running watches that support multiple GNSS are usually more expensive. They are more accurate because they are able to gather data from multiple satellite systems so whether you’re running in the woods or in the streets of Manhattan, your watch can give you accurate data that you can use in your training.
What Watches Support Multiple GNSS?
There’s a lot of watches that support multiple GNSS, but my favorites are:
- Garmin Forerunner 745 – A little expensive but is packed with features such as Spotify and on-wrist payment
- Coros Pace 2 – Simple, reliable, and really affordable
Garmin Forerunner 745 uses GPS, GLONASS, and Galileo for navigation. It’s a little expensive but I think it’s priced just right for all the extra features it offers. It’s perfect for those who like to concentrate on running without having to bring a cellphone for music.
If you’re a Garmin guy but don’t have the budget to buy one, check out this article that I made giving you the best Garmin running watches alternatives.
The Coros Pace 2, on the other hand, is a lot cheaper but is a beast of a device. It uses GPS, QZSS, GLONASS, and BeiDou as its navigation system. It’s packed with tons of sensors, and it has extraordinarily long battery life. Extraordinary for something that is this affordable. You can check its price on Amazon.
Final Thoughts
I hope this article has given you more knowledge about GPS watches and how they work. The whole purpose of this article is to give you an idea of what type of watch you should get.
