I did a test to control the radio transmission power of the raspberry pie that installed OpenWRT.
[How to test]
- Raspberry Pi (client) - Raspberry Pi (server)
- Upload files from client to server via scp command
- Change txpower through the command "iw dev wlan0 set txpower fixed xxx" (uci did not work, so we replaced it with a command.)
- Check the txpower set through the iwinfo command.
- The input cable was connected to the Spectrum Analyzer (8595E) and the other end of the cable was secured around the Raspberry Pi antenna chipset to measure the frequency.
Result : Frequency does not change significantly. For 0dbm -> 31dbm, the signal increased by 5dbm.
Usually, I think the signal should increase by 1 dBm every time txpower increases by 1 dBm, but it seems too small.
Is there another command or actual maximum txpower on Raspberry Pi4 that controls txpower?
please advice