regarding distance measurement for the nrf52840 and nrf52833

[liuluan1984]

Hi Nordic,

I am developing a distance measurement application between the nrf52840 and nrf52833 unit for the long distance mode. 

for the nrf52840 as center which running the  ble_app_uart_c_central example. 

I am trying to let the nrf52833 run with the ble_app_uart_peripheral example. 

1. Is the setup correct with the examples I am using?

2. Is there anyway to measure the distance between the two units?

3. how far the distance can be in the open area? 

4. how frequently can I measure the distance? I try to measure the distance each 50ms or 100ms, is that possible 

Thank you in advance 

[Edvin]

Hello,

There is really no way to measure the distance between two BLE devices. There is nothing in the specification that you can use for this. However, some use the RSSI to get a sense of the distance, but the RSSI (received signal strength indicator) depends on the antennas, the output power, the orientation of the antennas, reflections, background noise and so on. So while you can use it to detect whether you are close or far away, it is not really a good measure of distance in meters or centimeters.

Best regards,

Edvin

[liuluan1984]

is there any suggestion to use the AOA or DoA method to measure the distance from the nrf52833 side with the SDK17.0.2?

[Edvin]

The short answer is "no". The long answer:

1. It is not trivial to add AoA or AoD, and it requires a significant Hardware change. Your scanning device needs to have an antenna array of roughly 20x20cm. 

2. AoA/AoD will not give the distance. Only the direction, so this can not be used for distance measurement.

Best regards,

Edvin

[liuluan1984]

thank you for your reply, seems the size 20*20cm is too big for our system