Deviation of nRF9160DK GNSS measurement result

Hi,

A deviation is to be expected, especially if the dilution of precision is high in the initial fix.

You can calculate the GDOP (by squaring tdop+pdop) as described here:

https://en.wikipedia.org/wiki/Dilution_of_precision_(navigation)

Here's the *dop members in the pvt frame: 

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrfxlib/nrf_modem/doc/api.html#c.nrf_modem_gnss_pvt_data_frame.pdop 

And then add a limit for your wanted total DOP in your own application.

Easier alternative: You can let the GNSS run for a longer time period after getting a fix, by for instance filtering on the .accuracy field:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrfxlib/nrf_modem/doc/api.html#c.nrf_modem_gnss_pvt_data_frame.accuracy

PS: also make sure you're not in low accuracy mode: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrfxlib/nrf_modem/doc/gnss_interface.html#low-accuracy-mode

Kind regards,

Håkon

Hi,

A deviation is to be expected, especially if the dilution of precision is high in the initial fix.

You can calculate the GDOP (by squaring tdop+pdop) as described here:

https://en.wikipedia.org/wiki/Dilution_of_precision_(navigation)

Here's the *dop members in the pvt frame: 

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrfxlib/nrf_modem/doc/api.html#c.nrf_modem_gnss_pvt_data_frame.pdop 

And then add a limit for your wanted total DOP in your own application.

Easier alternative: You can let the GNSS run for a longer time period after getting a fix, by for instance filtering on the .accuracy field:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrfxlib/nrf_modem/doc/api.html#c.nrf_modem_gnss_pvt_data_frame.accuracy

PS: also make sure you're not in low accuracy mode: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrfxlib/nrf_modem/doc/gnss_interface.html#low-accuracy-mode

Kind regards,

Håkon

Is the range of deviations reasonable

If you are only tracking the bare minimum amount of satellites to obtain a fix, then yes.

Kind regards,

Håkon

thx

No problem, happy to help!

Kind regards,

Håkon