Disappearance of sensors and interference problem

Wireless Connectivity Ultra-Wideband
1

Hi.

I am working with many DWM1001 sensors for indoor localization.
Recently, anchors suddenly disappeared from a RTLS web manager and It quite frequently occurred.
Moreover, in some case, restoring anchors to the RTLS web takes much time or they not come back.
Simple solution was rebooting gateway or restart a DWM1001 service in gateway.

1.Interference from other signal
I tested with closed environment to find out reason of disappearance and found that an anchor disappears due to a WiFi signal.
As I activated WiFi module below the anchor (about 3m far), anchor was disappearing.
This situation was shown regularly.

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The WiFi uses 2.4~2.483GHz and 5.150~5.825GHz bandwidth and the DWM1001 uses 3.5GHz as I know.
I wonder that these signals can be conflicted.

Especially, in a corridor with many repeaters from bunch of mobile carriers, this symptom was serious.
preliminary solution to making stable was to increase the number of anchors.
Anchors and they are far from each other with 3 to 5 meters.

2. Interference from human body
In a multi-room environment with many DWM1001 sensers, when a person was passing through the door, anchor sometimes disappeared.

3. Tentative solution
In a Decawave forum I found similar situation.
https://forum.qorvo.com/t/anchors-disappear/8785

Restarting a DWM1001 service is a direct solution, but not perfect.
I also suspect that a MQTT broker is a one of a problem since a ‘present’ buffer fulled with ‘false’ are not clean.
As a result, anchors are not recovered form the RTLS web manager.

I think two things are problem

  • Interference of other radio waves e.g. WiFi, Mobile network
  • Malfunction of recovering anchor state from the MQTT broker

Including finding out a main reasons, I want to make a stable system.
Any advise please.

Thanks.

2

Hi @sojin
first of all the PANS system is using 6.5GHz with 500MHz channel bandwidth as it is ultra wide band. Cellular or wifi networks are narrow band and they should not not interfere.

Regarding 1 and 3)
Please check following:

  1. Do you use Raspberry PI 3B (only this version is supported)
  2. Do you use official Raspberry pi power source (5.2V) (very important)
  3. Do you use the mosquito from the official image?
  4. Do you use proxy MQTT proxy?

Regarding 2)
This is common problem: The human body is full of water and the hi frequency signals (even 2.4GHz Wifi) don’t like water as it is a great attenuator. As the frequency grows the attenuation increases. In general the UWB signal can penetrate trouch people but the signal loos is big.

Regarding your network)
Try to disable the C780 and 098E for a such small area you might not need them and the Location engine likes more “squared” networks.

Cheers
JK

3

Hi.
First of all, thanks for your reply.

Regarding 1 and 3)

  1. Yes. 3B model.
  2. I use 5v 2a adapter. Is there any problem?
  3. Yes. I am using provided one.
  4. Yes. I am using provided one.

Regarding your network)
What are C780 and 098E? How can I disable them?

Thanks.