Direction Finding Tx transmit power

RE: Direction Finding Tx transmit power

Edvin — Fri, 25 Mar 2022 09:44:16 GMT

Hello Marcous,

I believe this is what you are looking for:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/softdevice_controller/doc/api.html#c.sdc_hci_cmd_vs_zephyr_write_tx_power

[quote user="Marcous"]Only not to find the parameter of tx power[/quote]

I am not familiar with direction finding particularly, but I would not be surprised if the TX power is not part of the advertisement packet. There have been a few attempts of standardizing beacons the past decade, including iBeacon and eddystone, and there one option was to include the TX power in the advertisement packet, to give some sense of idea of how close you were when you receive the advertisement, and compare the RSSI and TX power. However, the RSSI is a very bad indicator of distance, so it may very well be that the TX power is not part of the advertisement packet in direction finding.

Best regards,

Edvin

RE: Direction Finding Tx transmit power

Marcous — Thu, 24 Mar 2022 14:49:49 GMT

Actually I do not need to change it dynamically while running. Obviously, with a higher Tx power, rx side would get the signal with a higher rssi value. I'd like to conduct an experiment to find out the relationship between BLE AoA direction finding performance and Rssi value ( in other word, tx power).

Besides, in the direction finding rx side, I can obtain some cte information like intervals, cte type, rssi value and so on. Only not to find the parameter of tx power. So I wondering is this Tx power feature available in the direction finding ? Maybe I have missed something in the whilepaper of ble direction finding?

Best regards,

Marcous

RE: Direction Finding Tx transmit power

Edvin — Thu, 24 Mar 2022 14:39:14 GMT

Hello,

You can't use the "old" softdevice (Bluetooth stack) API sd_ble_gap_tx_power_set() as this is not defined in NCS. That being said, it is actually a good question how to set the TX power during runtime.

I remember seeing some TX power configurations that you can set in the prj.conf file, but is that something that would work for you, or do you need to be able to change it dynamically during runtime?

Best regards,

Edvin