AntenaDelay

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skeletonSir
Beginner
Posts: 19
Joined: Thu Mar 22, 2018 6:34 am

AntenaDelay

Post by skeletonSir »

DWM1000 with PA is being used,How much antenna delay should be set,
dwTime_t delay = {.full = 0};
dwSetAntenaDelay(dwm, delay);

writeValueToBytes(dev->antennaDelay.raw, 16384, LEN_STAMP);
skeletonSir
Beginner
Posts: 19
Joined: Thu Mar 22, 2018 6:34 am

Re: AntenaDelay

Post by skeletonSir »

Use DWM1000 with PA, the distance is not accurate, need to revise where
arnaud
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Joined: Tue Feb 06, 2007 12:36 pm

Re: AntenaDelay

Post by arnaud »

The antenna delay is applied in software in our TWR algorithms, we have stopped using the antenna delay register in the DW1000.

I am not sure what you mean by "DWM1000 with PA", but if you are not using the stock DWM1000 you most likely need to adjust the antenna delay used in the TWR algorithm.
skeletonSir
Beginner
Posts: 19
Joined: Thu Mar 22, 2018 6:34 am

Re: AntenaDelay

Post by skeletonSir »

TWR mode ranging is correct, but TDOA mode ranging is wrong, because I used DWM1000 power amplifier, how should the antenna delay and time be modified?
skeletonSir
Beginner
Posts: 19
Joined: Thu Mar 22, 2018 6:34 am

Re: AntenaDelay

Post by skeletonSir »

To be exact, DWM1000 with power amplifier is tested with Anchor mode and tag mode in LPS. One Anchor and one tag, the test results are more consistent with the real results. Although there is a little deviation, it is adjustable, but the data analyzed by the aircraft end is wrong with 8 TDOA2 or TDOA3 Anchor points.What needs to be changed in the TDOA algorithm?
arnaud
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Joined: Tue Feb 06, 2007 12:36 pm

Re: AntenaDelay

Post by arnaud »

I understood the Power Amplifier part but I am still not sure of what hardware you are using, so to be clear: if you are using a DWM1000 module that is different than this one: https://www.decawave.com/products/dwm1000-module the antenna delay in Two Way Ranging mode needs to be re-calibrated.

As long as you are using similar UWB radio in all your system (ie. if all the antenna delay are very similar), you should not need any antenna delay calibration for TDoA: when calculating the time difference of arrival the antenna delay gets canceled.
skeletonSir
Beginner
Posts: 19
Joined: Thu Mar 22, 2018 6:34 am

Re: AntenaDelay

Post by skeletonSir »

The antenna is the same, namely the antenna and DWM1000 chip added a PA, as shown in the figure.In that case, the antenna delay need not be changed, where to change with TDOA mode?Timestamp?
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skeletonSir
Beginner
Posts: 19
Joined: Thu Mar 22, 2018 6:34 am

Re: AntenaDelay

Post by skeletonSir »

I'm going to use PA for the anchor point plus PA for the plane.Or make an airplane with PA as anchor point + PA, the data of TDOA is not correct
arnaud
Bitcraze
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Joined: Tue Feb 06, 2007 12:36 pm

Re: AntenaDelay

Post by arnaud »

When using TWR you must recalibrate the antenna delay, antenna delay is the delay of everything that is after the DW1000 radio I/O this include part of the silicon, traces on the PCB, antenna as well as any PA that is before the antenna.

Can you precise how does TDoA not work? We have never used these module so I have no idea about how they behave and what they could cause to the measurements.
john5648
Beginner
Posts: 7
Joined: Sat Nov 28, 2020 7:03 am

Re: AntenaDelay

Post by john5648 »

Hi
I just tested a TWR ranging accuracy between one node and one crazyflie.
The ranging data was from LoPoTab0 - ranging.distance0.
untitled.png
The data showed ranging error of over 300mm.

Is this also a problem of antenna delay?
If it is, is there some kind of criterion which value should I fit in? or should i just find the value experimentally?

Thanks!
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