4 anchor and one tag, Anchor signals interact with each other

[kamtatli]

Dear all,

The situation of the problem is I set the distance between anchor 1-4 and tag is 1m, and test each anchor to tag is 1m, when I turn on the anchor 1, the distance of anchor 1 to tag is 1m,
turn on anchor 2, the the distance of anchor 1 to tag become 0.9m, anchor 2 to tag is 0.88m,
turn on anchor 3, the the distance of anchor 1 to tag become 0.8m, anchor 2 to tag is 0.6m, anchor 3 to tag is 0.8m,
turn on anchor 4, the the distance of anchor 1 to tag become 0.8m, anchor 2 to tag is 0.4m, anchor 3 to tag is 0.8m, anchor 4 to tag is 0.2m,

@jremington for your example [ESP32_UWB_tag2D_4A], is that the anchors do not interact with each other? thank you for your attention.

[Half-Note]

Have you found a solution? I’m experiencing the same issue. I have two UWB anchors placed 3 meters apart. When only one anchor (A) and one tag are active, the tag reads a distance close to 3.0 meters. However, when I activate the second anchor (B), the measured distances from A to the tag and B to the tag become inaccurate, dropping to values like 2.2 or 1.7 meters.

[jremington]

I have not seen such an issue in extensive tests and these are the first reports of such.

Post the minimum code that demonstrates the problem, with tag and anchors clearly identified in the post.

[Half-Note]

For the anchor, I am using your code of setup anchor for each anchor, I have changed the delay and address. rest of the code remains the same.

// leftmost two bytes below will become the "short address"
char anchor_addr[] = "81:01:5B:D5:A9:9A:E2:9C"; //#81, 82
//char anchor_addr[] = "82:01:5B:D5:A9:9A:E2:9C"; //#81, 82
//calibrated Antenna Delay setting for this anchor
uint16_t Adelay = 16660;
//uint16_t Adelay = 16590;

For tag, I am using your 2D-3A. I have commented out the serial print lines for the trilateration point and others so that we can only see the d1,d2,d3. I have also changed the condition of 3 devices connected to 1. (I have not studied if this would have any effect. Because if this is set to 1 and once the 2nd and third devices when added the tag would take quite a time to read.)

the d1 is almost close to 2.0 when second anchor is off. once the second anchor connect the value drops to 1.69.
The UWB version I am using..

I have tried both your library and the makerfab as well. (Just for the distances from two or more anchors no trilateration or 2d plan resolution) both libraries have the same issue. makerfab definitely have an issue. but for your code when I ran the standard code for 2D-3A with the condition of 3 devices attached the code works fine the distance value reported are precise but not accurate almost off by 1 meter.

I will try to caliberate each anchor while the other two anchor are connected to tag. which may report a different antenna delay value but I am not sure what would be the cause of the issue. as reported by another user could it be due to interference with signals since all three devices are pretty close like <3m. (But it does not make sense if the packet has addresses and tof is calculated for each using that address).

[jremington]

For accurate distance measurements, it is essential to calibrate each of the anchors, first making sure that the antenna delay for the tag used in calibration is set to the default value.

[Half-Note]

The issue I encountered was related to the voltage supplied to the modules. I was using Makerfabs modules, and their voltage regulators were heating up significantly. To tackle that, I initially used voltage regulators to reduce the voltage and protect the modules. I powered them through power banks with voltage regulators in between, which resulted in an output of around 4.5V. However, after switching to an adapter supplying 5.35V at 2A, the issue was resolved. Makerfabs also clarified that it is normal for the voltage regulator to heat up and that it does not harm the module. (hint: an indication of the voltage problem could be the blinking of the light of the module the light should blink during ranging). My readings are almost +-6inch but they are good for my work!!!

[muhammadalimuzaffar]

Hello @Half-Note I encountered the same issue which you were encountering that using 3 anchors and tag distance readings become inaccurate but the difference is that I am not using makerfabs modules but I bought dwm1000 modules separately and make my own PCB for DWM1000 buy heading all its pin through female headers but using only VCC, GND, MISO, MOSI, SCK, SS, RST, IRQ pins. I made four PCB's for 4 DWM1000 UWB modules 3 as an anchors and 1 as a tag and each PCB has its own esp32. What you discussed is that if one is not getting accurate distances using multiple anchors then one reason can be of the power issue? When I was testing I was connecting all anchors with the laptop USB port and tag was also connected with laptop USB port.

@jremington , @Half-Note or any one can please help me out to get rid of this issue? Thanks in advance fir any help.