Calculate GPS accuracy in meters

[Chris Burns]

There are other GPS modules on the market which can give information like "the device is within 10 meters of the given coordinates". Is there a way to either get this information from the nRF9160 or calculate it from the information it provides?

[Heidi]

Hi!

According to the GPS Elspecs, the accuracy of the GPS is between 3 - 5 meters. So the application could compare the coordinates from a GPS fix and the specific coordinates you want to investigate.

It doesn't look like we have anything like this already programmed in NCS, so you would have to implement it yourself. To learn more about calculating the distance between two coordinates, take a look at this page or this page.

Best regards,

Heidi

[Chris Burns]

I think I need to clarify what I meant. I'm looking for a way to know the possible error in the latitude and longitude given by the GPS when it gets a fix.

For example, when the NRF_GNSS_PVT_FLAG_FIX_VALID_BIT is set, is there a calculation that tell what the accuracy is (like this fix is within 5 meters or within 3 meters)?

[Chris Burns]

Apparently the information I was looking for is already in the PVT notification. It's the accuracy field and the comment in nrf_socket.h is:

float accuracy; /**< Accuracy (2D 1-sigma) in meters. */

So that field will give the accuracy to within one standard deviation.

[Heidi]

Hi, yes you're correct. 

The accuracy field of the PVT notification gives an estimated standard deviation for the fix accuracy, so if the accuracy field is e.g. 5, the fix is estimated to be within 5 meters with 67% probability. 

Best regards,

Heidi