Check results related with change TX power and RSSI values.

[sotillo2409]

Hi everybody,

I am working with two custom boards with nrf52840 chip, using the examples of UART central/peripheral.

I set power TX of connection exactly as the example shows: https://github.com/nrfconnect/sdk-zephyr/blob/master/samples/bluetooth/hci_pwr_ctrl/src/main.c

I set this power on centran andperipheral, when connected function is triggered.

With the minimum db=-40:   

My values of RSSI every ten seconds: 

With the max db=+8:   

My values of RSSI every ten seconds:

My questions are:

Is it normal this results? this meassure of RSSI make sense? Is it possible put up the tx power more than +8db??

I am on indoor location, with both devices near one each other

Thank you, 

regards.

[Jared]

Hi,

Is it possible put up the tx power more than +8db??

 No, that is the maximum tx power for the nRF52840.

Is it normal this results? this meassure of RSSI make sense?

 It's difficult to say, RSSI is not an accurate estimate and depends on several external factors. You also mentioned that you use a custom board, have the board been properly tuned? Try flashing your example to a nRF52840 development kit and see what RSSI you get in the same environment. 

regards

Jared 

[sotillo2409]

That is a cool idea, i tried it with nrf53 with default tx settings connecting with my custom board and i get around  -35dB. 

My custom board is a fanstel bc840 with an external ANT.

I am not so convinced about the results.

All of this is to try a long range test, and until now my maximum distance was on 600 meters aprox on free obstacles line, using coded PHY between 2 custom boards. The test was on a industrial area with considerable noise.

[Jared]

Hi,

Have you tuned your custom board? 

Preferably I would like you to compare it with a nRF52840 DK not a nRF5340 DK. Nevertheless you get somewhat a similar result, maybe that indicates that your result is the expected for your environment. 

regards

Jared

[sotillo2409]

Hi,

Jared said:

Have you tuned your custom board? 

No, i didn't tunned, i don't have a nrf52840 DK , because of that i compared with nrf5340 DK.

Yes more or less the data between devices makes sense so I conform with it.

Thank you for check,

regards.