DW3000 Second Antenna

Hello Qorvo,

I am measuring distance with DW3000 based on TWR technique. I use Ipatov RX timestamp to calculate distance.
When I changed the RF config as;

STS mode = DWT_STS_MODE_1
PDOA mode = DWT_PDOA_M3

As I know, two STS frame transmit air. to read TDOA and PDOA.

When I connect two identical antenna to two port with SMA RG58 cable, I be able to continue measuring distance but something weird.

The measured distance doesn’t change when I keep fix the board position and niter first antenna nor second antenna close or far to mobile tag. It is as if the measurement is based on the position of the card, not the position of the antenna. I know the signal comes from first antenna, because when I disconnect the first antenna DW3000 can’t receive any packet. But oppositely it can measure distance when I disconnect the second antenna.

My aim that, calculating angle with using TDOA and distance by keeping the distance between the two antennas about 1m. But i must be know the two antenna behavior before the final design.

How high do you have the transmit power and how well shielded is your pcb?

UWB picks up the first signal it sees not the strongest. The signal will travel through the air faster than it can travel through your antenna cable. If the signal is strong enough and the circuit isn’t well shielded the PCB traces can act like an antenna and pick up the transmission before the signal from the real antenna arrives.
I’ve even see this where the signal jumped from the air onto the cable where it had a bend and so the signal skipped most of the cable.

The impulse response data will tell you if this is happening. You will see a weak first pulse followed very closely by a far stronger pulse.

Also when using cabled antennas make sure you calibrate for the cable delay and check it regularly. A connector not being done up tightly can make a few cm of range difference.

It sounds like you are using the DW3000 module to perform two-way ranging (TWR) using time-difference-of-arrival (TDOA) and position-difference-of-arrival (PDOA) measurements. The STS mode and PDOA mode settings you mentioned control how the DW3000 module performs these measurements.

If you are experiencing strange behavior when measuring distance, it could be due to a number of factors. For example, the accuracy of the distance measurement may be affected by factors such as the quality of the RF connection between the DW3000 module and the antenna, the strength and quality of the RF signal, and the accuracy of the timing measurements. It’s also possible that there may be issues with the configuration of the DW3000 module or with the software or firmware that you are using to perform the measurements.

To troubleshoot the issues you are experiencing, you may want to try the following:

  1. Check the RF connection between the DW3000 module and the antenna to ensure that it is secure and that there are no issues such as damaged cables or connectors.
  2. Verify that the RF signal strength and quality are sufficient for accurate measurements. You may be able to do this by using a spectrum analyzer or other RF measurement tools.
  3. Check the configuration of the DW3000 module to ensure that it is set up correctly for the TWR measurements you are trying to perform. You may want to consult the documentation for the module to ensure that you have the correct settings.
  4. Review the software or firmware that you are using to perform the TWR measurements to ensure that it is correctly configured and that it is compatible with the DW3000 module. You may need to refer to the documentation or seek help from the software or firmware developer if you are having trouble understanding how to use it.

I hope this information is helpful. Let me know if you have any further questions or if you need more assistance.

It sounds like you are using the DW3000 module to perform two-way ranging (TWR) using time-difference-of-arrival (TDOA) and position-difference-of-arrival (PDOA) measurements. The STS mode and PDOA mode settings you mentioned control how the DW3000 module performs these measurements.

  1. TWR is a fundamentally different system to TDoA - you use one or the other. Not both.
  2. PDoA is Phase difference of arrival not position difference.

My bad. I’m sorry about that.