decawave ranging problem

lidiya_john_v · February 17, 2018, 5:11am

Hi all,

I am using Trek EVB1000 decawave module for indoor navigation . I am facing ranging problem when obstacle (human or any other mateial)is coming in between 2 anchors.
next problem is ,when we are beyond 8m its tag showing 0 values. So what should i do to solve this problem.

thank you,
Lidiya john v.

leoTheunissen · February 17, 2018, 5:34pm

Hi,
As the body introduces approximately 30 dB insertion loss, the LOS signal may be attenuated too much and not received and the distance reported may actually be due to a reflection from a nearby object (wall, ground etc).
We are aware of these losses caused by the body, see also our application note APS006 Channel Effects on Range accuracy.

In General, proximity to the body will reduce the antenna efficiency and reduce the fidelity factor. This could distort the UWB pulse and thereby give an incorrect range measurement and so one might require to design an antenna which takes the body proximity in account.
About your next problem, could I ask if this is this with the body blocking the signals?
You could also analyse the logfile. See chapter 8 ANALYSIS in the TREK1000 User manual.
/L

jinlu8591 · February 17, 2018, 11:39pm

Leo,

Regarding you comment “design an antenna that takes the body apprroximation into account”. Could you be more specific on how antenna can remedy the situation? Did you mean having an antenna than gives you a line of sight? That may not always be possible if that is the case.

Having body approximation may be a requirement for some apps, so this may limit the application of UWB, I am afraid.

lidiya_john_v · February 19, 2018, 6:33am

leo Theunissen:

Hi,
As the body introduces approximately 30 dB insertion loss, the LOS signal may be attenuated too much and not received and the distance reported may actually be due to a reflection from a nearby object (wall, ground etc).
We are aware of these losses caused by the body, see also our application note APS006 Channel Effects on Range accuracy.

In General, proximity to the body will reduce the antenna efficiency and reduce the fidelity factor. This could distort the UWB pulse and thereby give an incorrect range measurement and so one might require to design an antenna which takes the body proximity in account.
About your next problem, could I ask if this is this with the body blocking the signals?
You could also analyse the logfile. See chapter 8 ANALYSIS in the TREK1000 User manual.
/L

Thank you Leo for your reply .about my next problem ,when the tag moves beyond 8 meters it is not showing corresponding distance with anchors without any body blocking the signal, the line of sight was free .

leoTheunissen · February 20, 2018, 2:34pm

Hi,
Just to confirm again. Do you have a TREK1000 or EVK1000?

IF TREK , make sure the three anchors are on the same height, and are in sight of each other.
Is the TAG moving in the TRIANGLE formed by the three anchors? Or outside the triangle?
Could it be that at least 1(3) anchors is out of range for the TAG?
/L

/Leo

lidiya_john_v · February 21, 2018, 5:55am

Hi,
I am using trek 1000.

“make sure the three anchors are on the same height, and are in sight of each other.”
yeah , sure . Because some times they are not in the same height.

tag moving outside the triangle formed by the 3 anchors but inside the square .
All 3 anchors forms a equilateral triangle to make a square.(25m*25m).
Performing the experiment within this square.

thank you,
Lidiya.