nrf52832 RSSI varitaion

[guma]

Hi,

We are using nRF52832(lairdBL652) module for indoor application for the prototype version.

We are using nrf52832  for both central and Beacon device.

We have made a setup as per the attached document for testing,

We are able to read the RSSI of the beacon from the Central device,

For our project we want to get the RSSI of around -85 dBm at 3m at TX power level of -12dBm.

When the peripheral device is moved closer or farther to the central module, the RSSI variation can be observed respectively,But the variation in RSSI is very abnormal.

This is the test case.

1) when the reader and the beacon are placed as per the above diagram in the same orientation, at different time interval the RSSI values varies.(not obtaining equivalent or similar values for each time we test)

for instance in one trial at 3mtr we are getting the values of around -85dBm,

in another trial we get around -92dBm.

2) when the reader orientation is changed, We observed change in the Beacon RSSI of about 2 to 3 dbm, but the RSSI values obtained in one trail of testing , is not obtained again.

Is this module suitable for indoor asset tracking and not just for proximity?

Kindly support on this ASAP.

Regards,

Uma

[awneil]

guma said:

the variation in RSSI is very abnormal

Why do you say that?

There's a huge number of things that affect RSSI - especially indoors where you have loads of reflections, multipath, interference, etc.

People moving about will affect it.

IME, it is perfectly normal to see quite large variations in RSSI even when the receiver & broadcaster are static.

This is exactly why precise location using RSSI alone is impossible - it keeps coming up all the time on the forum!

[guma]

Hi awneil,

We understood what you mentioned.

We have tested and observed as per what you said about people moving about will affect, large varitaions in RSSI when the receiver and the broadcaster are static, also when the receiver is at a height from the broadcaster.

But what do you suggest or recommend ,other than RSSI for indoor application on nrf52832 using BLE technology.

Thanks

[BeepBeepImAJeep]

Bluetooth 5.1 introduced AoA (angle of arrival) and AoD (angle of departure) functionality which should improve the possibilities for asset tracking. Nordic has a blog about it here https://blog.nordicsemi.com/getconnected/bluetooth-5.1-puts-bluetooth-in-its-place

Though it seems it would require nRF52811

[awneil]

BeepBeepImAJeep said:

it would require nRF52811

Indeed.

And the support for that is not yet available.