Rance accuracy

Wireless Connectivity Ultra-Wideband
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1

Hi to all

I have reproduce on my hardware the example 06 from dw1000_api_rev2p04 package and it work but the accuracy is not so good.
I have some problem

  1. when I switch on anchor and tag i get a distance totaly wrong (real distance 1,5 m but i get more than 2,5 m) after some time (30 - 40 sec) it gets better and start to give me the correct distance.

  2. seem that leaving anchor and tag on and make a continuos range every 2 second at fixed distance (1,5 meters) after some time the performance decrease again.

  3. seem that people moving in the room affect the quality of the measure.

Have you any suggest?

I try also to open the decarangeRTLS project with CoIDE but always get this error:

"Chip: ‘STM32F105RC’ did not download. Whether to download chip and continue

But CoIDE seem that is unable to download the chip data. I use Version: 2.0.7 Build id: 20170510-2.0.7 of CoIDE. Is this version correct?

2
  1. This could be related to Crystal start up time, Please see APS011 , Source of error in two way ranging.
  2. as above. The TAG might go into sleep between the during ranging. What happens if you have the TAG always “on”?
  3. This behaviour is explained in application notes: APS006 part 1 (channel effects on range accuracy)., 2 (nlos operation and optimizations) and 3 (dw1000 diagnostics for nlos channels)
    All these are available under “Range and Accuracy” on https://www.decawave.com/application-notes

The dw1000_api_rev2p04 requires coocox 1.7.8.
/Leo

3

Hi Leo

Thank you for the answer.

I have another question. I see on AN006 part 1 that in case of obstruction in direct path i have a distance over stated by a factor calculated with this formula:

Wx(R-1)

Where W is the width of the obstruction and R is the refractive index.

My question is the result of this calculation is distance error or a kind of corrective factor?

In my case i have an human body (30 cm for example) between Transmitter and receiver so i have a result of

30x(7.14-1)=184,2

How can i use this result ? Is it a distance to sum to subtract? And more important, can i estimate this number from DW1000?