How to set BLE tx power

[Hendrik]

For a school project I need some BLE beacons to advertise in the background.
I'm currently using this example project: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.3.0/zephyr/samples/bluetooth/beacon/README.html

I believe it's only transmitting with 0 dBm. I'd like to change this to the maximum of 8 dBm.

Adding the line "CONFIG_BT_CTLR_TX_PWR_ANTENNA=8" in my config didn't seem to have any impact.
Another option I saw was adding some params to the "bt_le_adv_start()" method but I'm not sure how to structure these params.

Any other solutions are welcome. At the end of the day I just want to advertise to the 3 BLE adv. channels with as much tx power as possible.

[Hung Bui]

Hi Hendrik, 

It should work. I did a quick test here with peripheral_lbs example and when I add 

CONFIG_BT_CTLR_TX_PWR_ANTENNA=8

I can see on the phone (via NRF Connect app) that the RSSI increased quite a lot (-33dBm at 0dBm txpower and -22dBM at 8dBm txPower)

Also I can see the current consumption increased when I use 8dBm 

Another thing you can try is to control the tx power dynamically. See here: 

How to set TX power to maximum +8dbm for advertising as well as when connected

[Hendrik]

I tried changing it through Kconfig which edits zephyr/config and manually by putting it in my proj.conf. Neither seem to have any impact. When creating a new build configuration, should I select a particular option (system default vs proj.conf)? 

Edit: it seems like my signal strength varies a lot but I do see a difference between -8 and +8 dBm

[Hung Bui]

Hi Hendrik, 

I assume the problem is solved ? 
You should be able to clearly see the difference in the range when you do -8 and +8dBm. You can just use a phone to verify that. 

[Mariano]

Hi, I'm testing this feature. What is the maximum value I can setup for CONFIG_BT_CTLR_TX_PWR_ANTENNA. I can't find any reference in the documentation

[Hung Bui]

Hi Mariano, 
Please create a new ticket if you have follow up question as it's a closed ticket. 
The maximum value of CONFIG_BT_CTLR_TX_PWR_ANTENNA should be the maximum value of TX Power of the chip. You can find this in the specification of the chip. Here maximum TX Power of nRF52840 is +8dBm.