Bluetooth Tx power level


Hi all,
need help on this
when i enquire tx power level initially with
hciconfig hci0 inqtpl it returning 8.

But if enable scan giving hciconfig hci0 piscan then tx power level changing to 4

why is it so?



Debian or OE/RPB ?

This is weird, on db410c rpb console image, Bluetooth always report 2dBm for inquiry transmit power level.
Could you run btmon in parallel of your commands ?

It’s possible that depending the environment, firmware adjusts its power (automatic power control algorithm).


This is on debian 4.9.27.

what actually the btmon will do?

i did run both then got this info

hciconfig hci0 inqtpl

@ RAW Open: hciconfig (privileged) version 2.22 {0x0003} 16.495925
@ RAW Open: hciconfig (privileged) version 2.22 {0x0004} [hci0] 16.496535
< HCI C {0x0003} 16.507310



bmon for btmonitor dump all HCI data traffic between the host and controller (bt-chip), to run before running your hciconfig/tool commands.


Thanks for providing the info.Now i can analyze on it.