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CC2652P: AoA Measurement Evaluation (Coverage, Multi-slave)

S L61
Intellectual 780 points
Part Number: CC2652P


Hi everyone, 

I am evaluating AoA function of BLE5. I choose CC26X2R1 Launchpad as my starting point and can do AoA measurement with one master and one slave now. For the actual use in my project, I still have some questions about AoA function of the SDK before going further.

1. To cover 360 area, is there any method that TI recommends? I am thinking to use one master with multiple antenna arrays or one master with multiple passive devices. Seems multi-passive is more practical since using multiple antenna arrays adds complexity in timing and synchronization.

2. To extend the coverage, I am thinking using CC2652P, which integrate a 20 dBm PA. Since AoA is based on BLE connection, I use RF range estimator to calculate the coverage. With 20 dBm PA setting, CC2652P  can reach around 400m. Is it possible to do AoA measurement at that range and how is the accuracy? In my project, the actual place is an open area (1 - 2 kilo meter square) with very few obstacles in sight and there will be multiple slaves moving across the working area. Multiple masters needs to do AoA measurement of these slaves. 

Thanks in advance.

Sean

  • 0
    TI__Expert 5345 points

    Hi!

    Thanks for your interest in our products.

    I'm going to assign your question to one of our AoA experts who will be able to help you.

    Thanks,

    Luis

  • 0
    TI__Guru** 101460 points

    Hi Sean,


    1- I see a small confusion in your first question. Adding nodes does not increase the angle coverage. Adding some nodes increase the positioning precision (see triangulation theory).
    The area covered by the antenna has to match the area where the target can be. If the antenna only covers 180 degrees, then you have to be sure the target won't be out of these 180 degrees. If the target is out of these 180 degrees, then the results will be wrong (the antennas will still receive the BLE signals but the interpretation of the phase will be wrong).

    2- The accuracy of the technique is 2-4 degrees (depending on the antennas and the algorithms used). The further the target is from the locator, the bigger the distance error is.
    For 400m distance, a simple estimation of the error is 400*tan(3)=19m

    I hope this will help,

    Best regards,

  • 0 in reply to Clément
    Intellectual 780 points

    Hi Clément,


    Thanks for your reply. For Question 1, if I want to cover 360 degrees, then I redesign a new antenna covering 360 degrees instead of using multiple passive nodes with different antenna direction. Am I right? Assume these passive nodes are in one device, I plan to use a back-end PC to filter out wrong values. From RTLS example, I found the angle deviate a lot when slave is out of antenna's coverage. Then I think it may be workable to use some software techniques to do the filtering.

    Thanks for your time.

    Best,

    Sean

  • 0 in reply to S L61
    TI__Guru** 101460 points

    Hi Sean,

    For Question 1, I suggest to use only one master node with a 360 degrees antenna. No need to have several devices (hence lower cost and lower power consumption).

    Regards,

  • 0 in reply to Clément
    Intellectual 780 points

    Hi Clément,

    Thanks for the suggestion. For a 360 degrees antenna, I need to use several RF switches to do sampling on CTE. Then total time for switching and sampling should be within CTETime, am I right? As a starting point, seems I need to use both antennas on BOOSTXL-AOA then design a 360 degrees antenna. 

    Best,

    Sean

  • 0 in reply to S L61
    TI__Guru** 101460 points

    Hi Sean,

    Your understanding is correct.

    Best regards,