wireless-regdb: Wrong ETSI tranmit power without TPC

Alexander Wilhelm
2025-05-06T13:38:55Z

Hello devs,

please correct me if I'm wrong. Since TPC is not used, the EU Rules dictates to
decrease the transmit power by 3 dBm on some sub-bands. For the most of the EU
countries the mW instead of dBm is used. Therefore they are halved (e.g for
Germany (DE) in commit 81d251dda3985e1088bd89f5d9f565e63ba5a30f). The problem is
that the values are then converted to dBm and rounded down and result in a wrong
supported value. Take a look at example (Germany again):

country DE: DFS-ETSI
(2400 - 2483.5 @ 40), (100 mW)
(5150 - 5250 @ 80), (200 mW), NO-OUTDOOR, AUTO-BW, wmmrule=ETSI
(5250 - 5350 @ 80), (100 mW), NO-OUTDOOR, DFS, AUTO-BW, wmmrule=ETSI
(5470 - 5725 @ 160), (500 mW), DFS, wmmrule=ETSI
# short range devices (ETSI EN 300 440-1)
(5725 - 5875 @ 80), (25 mW)
# WiFi 6E
(5945 - 6425 @ 320), (23), NO-OUTDOOR, wmmrule=ETSI
# 60 GHz band channels 1-4 (ETSI EN 302 567)
(57000 - 66000 @ 2160), (40)

For the frequencies 5250 - 5350 the power of 100 mW results it 20 dBm. Correct.
The frequencies 5470 - 5725 have a power of 500 mW. It results in 26 dBm. But I
believe 27 dBm are allowed. For the frequncies 5725 - 5875 the value of 25 mW is
also dictated. I'm not sure if I should expect 14 dBm, but I get 13 dBm.

Is there inconsistencies between dBm/mW conversions? Please give me a feedback.

Best regards
Alexander Wilhelm