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Original question:

BOOSTXL-AOA: Questions Regarding Accuracy

BOOSTXL-AOA: Connection loss when wall is between devices

Rohit Joshi2
Prodigy 110 points

Part Number: BOOSTXL-AOA

Hello,

I am testing your BoostXL AoA board with the CC26x2 launchpad using the RTLS demo. However, when one of the devices is moved into a room, or behind any wall it almost immediately loses connection, regardless of the distance. Is there anything we can do to prevent this from occurring?

  • 0
    TI__Guru 57865 points

    Hi Rohit,

    Bluetooth low energy operates on the 2.4GHz band which is not really suitable for through-wall connections. It should be avoided.

  • 0 in reply to J Lindh
    Expert 1171 points

    According to TI RF Range Estimator document listed on the LAUNCHXL-CC26X2R1 website, we still should get a reasonable range even through walls (attached the calculator for reference).

    I agree that walls are going to degrade the signal strength but the LAUNCHXL-CC26X2R1 has enough link budget (~100dB) to afford penetrating multiple walls depending on the materials as shown by the calculator. The link budget calculated as 5dBm Tx output power, -2.30dBi Tx+RX DN007 antenna gain and -97dBm Rx sensitivity at 1Mbps data rate which can even be improved by going down to 125kpbs. A dry wall on the other hand will roughly degrade the signal by about 1dB and a brick wall will degrade it by about 8dB.

    Based on this I believe the device should still measure the distance through wall using ToF or/and AoA. Please let me know if I am missing something here. Thanks!

  • 0 in reply to Mustafa Homsi
    TI__Genius 9215 points

    Hi Rohit,

    Can you elaborate on your test setup? Do you have the BOOSTXL-AoA board on the Master, the Passive or both?

    You say that you loose connection, I assume you mean the BLE connection then (the BLE connection between Master and Slave)?

    What RSSI reading to you have when Slave, Master and Passive are placed close together in the same room?

    If you don't use the BOOSTXL-AoA board and use the antenna on the Launchpad instead, do you still loose connection? The reason for asking is that BOOSTXL-AoA antennas are less efficient (shorter di-poles) so that the antennas can be placed closer together.  

    Best Regards,

    R.M 

  • 0 in reply to R.M
    Prodigy 110 points

    Hi RM,

    We are using the Aoa board connected to the passive node and the passive node follows the connection between the Master and the Slave.

    We loose connection as in the RTLS monitor GUI stops showing received packets.

    Yes using just the antennas on the launchpad we still loose connection, and the TOF data is less accurate.

    Thanks,

    RJ

  • 0 in reply to Rohit Joshi2
    TI__Genius 9215 points

    Hi Rohit,

    Since you loose connection when using the Launchpad antennas too I do not think the problems is in the BOOSTXL-AoA and your HW.

    So is it only the passive you move around and the slave and master are kept close together?It's the passive that stops following the connection while the connection between the slave and master are still ok?

    What RSSI reading to you have when Slave, Master and Passive are placed close together in the same room?

    Best Regards,

    R.M

  • 0 in reply to R.M
    Prodigy 110 points

    R.M,

    The slave is moved around while the master and passive are kept close together.  RSSI values are from -62 to -65 in close proximity. Both the master and passive stop receiving packets from the slave, when there is a wall.

    Thanks for your help.

    RJ

  • 0 in reply to Rohit Joshi2
    TI__Genius 9215 points

    Hi RJ,

    If your RSSI values are from -62 to -65 when they are in close proximity your Tx output power is not as it should be.

    What device and SDK are you using?

    Have you applied fixes listed here:https://e2e.ti.com/support/wireless-connectivity/bluetooth/f/538/t/770223

    Best Regards,

    R.M