Distance Measurement Accuracy

[ptejasv]

Hello and thank you for your help.

I am working with the nrf52840 for a project that uses distance estimates. I have tried the sample Bluetooth: nRF Distance Measurement with Bluetooth LE discovery using MCPD. Can I check if there are any accuracy estimates for the MCPD ranging mode or any tested margin of error? I would like to see if the measurements I am getting are within the expected range.

Thank you.

[Simonr]

Hi

Please check out the slides from the Nordic distance toolbox webinar available here. In high precision mode you can see that the standard deviation is ~37cm, which is for example in an office environment with a lot of noise this gives reliable results up to 10 meters. In less noisy environments this increases, but testing should be done to find what you can expect.

Best regards,

Simon

[ptejasv]

Thank you for your help.

Can I check what the testing environment for the slides were like? From slide 23 I can see it's an office setup, but could I know if the DKs were positioned to face each other or if there was a lot of metal in the surroundings?

I've been testing with multiple DKs and I seem to be getting readings around 9 metres even with high precision for a physical distance of 6 metres. The graph below shows the output measurements for a constant distance of 6m over 2 minutes (277 readings).

At 3 metres, high precision readings seem less consistent as well. The graph below is measured distance against reading number for 240 readings over 2 minutes at a constant distance of 3 metres.

For the setup, I had the 2 nRF52840 boards on the floor with a metal measuring tape between them. Any interfering WiFi was turned off as well. Are there any other envrionmental considerations I should make?

I setup the high precision by adding the line CONFIG_DM_HIGH_PRECISION_CALC=y to the proj.conf file for the distance measurement sample. It looks like it's working, since I get far more readings over 2 minutes without using high precision, which I assume is expected since high precision takes more time to compute. Please let me know if this is the right way to configure high precision as well.