Why Do GPS Coordinates Differ

Why Do GPS Coordinates Differ?

Finding your position on a map has never been easier and most people now routinely use GPS to navigate their way to a new destination.

Still, there are many instances when the GPS coordinates on your device seem to differ from what you’re actually seeing around you.

Why is that?

To answer this question, let’s go over what GPS is and how it works.

Keep reading!

What Is GPS And How Does It Work?

What Is GPS And How Does It Work

GPS stands for Global Positioning System and uses satellites to indicate the precise geographic location of a building, moving car, or a person lost in the middle of nowhere with a phone in their hand.

GPS coordinates refer to a combination of latitude and longitude, expressed in alphanumeric characters.

How Does Your Device Use GPS?

Any GPS device, including your mobile phone, is equipped with a microchip, a small antenna, and a processor that can capture the signal of orbiting satellites to determine your terrestrial coordinates.

Most devices use the triangulation method, based on the signals sent by three or four satellites.

Why Do GPS Coordinates Differ?

Two people using an Android device and an iPhone in the exact same location will be surprised to discover that the GPS coordinates differ.

It might not be much of a difference, but even a few meters seems odd.

It’s not that one device is more accurate than the other, it’s just that they use a different method to calculate those coordinates.

Reason #1 On Why Do GPS Coordinates Differ: Mobile Device GPS Systems

Mobile Device GPS Systems

Android devices use what is known as “True GPS”:

The chip on the phone and the processor allow the device to determine the coordinates of a location by decoding and triangulating the radio signals coming from at least 4 satellites.

It does everything on its own without external help.

iPhone devices use “Assisted GPS”, and “GLONASS”:

This stands for the Russian Global Navigation Satellite System.

As opposed to True GPS, Assisted GPS takes the information received from the satellites and uses network data to augment the signal location.

While this additional information can be helpful, it can also influence the reading.

It’s hard to say that one system is better than the other, they’re just different.

Reason #2 On Why Do GPS Coordinates Differ: Positional Accuracy

Another reason why two devices might come up with different coordinates for the same location is the Positional Accuracy of the devices themselves.

A good device will have an accuracy of up to 10 meters – what this means is that the device can pinpoint a location with a 10 meters, plus or minus error margin.

When you use two devices to measure the coordinates of a particular location, it might very well be that one gives you a plus 10 meters reading while the other indicates a minus 10 meters reading.

When you compare the two readings you get a 20 meters difference, which seems quite a lot.

At present, companies selling GPS devices strive for a plus/minus 1-meter margin of error.

Reason #3 On Why Do GPS Coordinates Differ: Time Difference

Finally, the time the readings are made may also influence the results which is why GPS coordinates may differ.

Even using the same device in a certain location might give you a different set of coordinates at one-hour intervals.

This has to do with the position of the satellites used to triangulate the geographical location, but also with the atmospheric conditions, which can influence the accuracy of reading, even if only slightly.

GPS Coordinates Difference