GPS accuracy

RE: GPS accuracy

Amanda Hsieh — Tue, 04 Mar 2025 14:19:15 GMT

Sorry for the late reply.

[quote user="Shanmukh Araveeti"]1) What is STD value in the table?[/quote]

STD means standard deviation.

[quote user="Shanmukh Araveeti"]2) So, how I can get 2D fix as it seems that 2D fix has less error than 3D fix. [/quote]

To get the "2D fix", take the 3D fix and ignore the altitude component. The altitude component of the fix is less precise than the latitude and longitude components. Even if the fix is the same, the 2D and 3D error are different.

[quote user="Shanmukh Araveeti"]3) The readings which you shared are based on standalone or A-GPS and taken in periodic or continuous mode.[/quote]

The figures are for continuous tracking without assistance.

RE: GPS accuracy

Shanmukh Araveeti — Tue, 04 Mar 2025 05:23:04 GMT

Any update?

RE: GPS accuracy

Shanmukh Araveeti — Fri, 28 Feb 2025 07:35:15 GMT

Hi Amanda,

Thanks for your quick response.

1) What is STD value in the table?

2) So, how I can get 2D fix as it seems that 2D fix has less error than 3D fix.

( I do understand readings provided by you and in product specification sheet are taken in ideal condition).

3) The readings which you shared are based on standalone or A-GPS and taken in periodic or continuous mode. Please let me know.

Regards,

RE: GPS accuracy

Amanda Hsieh — Thu, 27 Feb 2025 14:19:55 GMT

Hi,

1) Yes, this is the correct interpretation. In other words, CEP refers to the radius of a circle in which 50% of the values occur.

Here is more detailed results from a test that is done with similar ideal assumptions as the data sheet test. This should not be understood as a guarantee that this performance can be consistently achieved but can be used for illustrative purposes only! 68 means "CEP68" etc. "Max" would be the "CEP100" that was achieved in this particular test. It is not realistic to make promises about CEP100 in product specification due to non-deterministic nature of GNSS position accuracy especially in challenging environments.

2) nRF9151 always outputs a 3D fix. It's just that most customers are only interested in the latitude and longitude of the fix and therefore we don't provide this data in the product specification. The altitude component of the fix is less accurate dues to GPS system design.

I would like to remind that all the numbers I presented (as well the product specification values) are obtained in ideal conditions (high quality roof top antenna, stable room temperature etc.). I encourage you to get hold of nRF9151 development kit and test for yourself to get a very realistic understanding about the performance in your particular use case!

Regards,
Amanda H.

RE: GPS accuracy

Amanda Hsieh — Wed, 26 Feb 2025 17:47:24 GMT

Hi,

I am working on your case and will update it when I collect enough information.

Regards,
Amanda H.