GPS: How Accurate Is It, And Can We Always Trust It?

[John]

GPS: How Accurate Is It, And Can We Always Trust It?

Most of us take satellite navigation for granted. We open a map on our phone, see a little dot showing where we are and expect it to guide us correctly.

But GPS has some surprising features.

A receiver normally needs signals from at least four satellites, and the calculations depend on extremely accurate clocks. Even Einstein's theory of relativity has to be taken into account!

Another interesting fact is that GPS satellites do not need to track our phones. The receiver calculates its own position from signals broadcast by the satellites.

A few questions for everyone:

• Has GPS ever directed you to the wrong place or along an unsuitable road?
• Do you trust satellite navigation more than traditional maps and road signs?
• Have you used GPS successfully without mobile reception or internet access?
• Have you noticed inaccurate locations in cities, tunnels or rural areas?
• Do you worry about applications collecting or sharing your location?

I've put together an article explaining how satellites determine position, why four signals matter, what affects accuracy and how smartphones use other location methods.

Read the full article: How Does GPS Determine Your Location?

What has your experience been with GPS and satellite navigation where you live?