Hello,

the status of my OmniTIK 5ac is:
Channel: 5660/20/a/DP(19dBm)

My wireless settings are:
Frequency Mode: regulatory-domain
Country: germany
Installation: outdoor
and Tx Power Mode: default

Why is there a limit (or a default setting) of 19dBm? Maximum legal power for Outdoor devices at channels 100-140 or 5.5 to 5.7GHz with DFS in Europe is 1 Watt or 30dBm.

The antenna gain of this device is 7.5dBi.

30 - 7.5 = 22.5

So legal limit of TX power should be at least 22dBm, not 19? Twice as much...

It´s not a technical reason, the maxium transmit power for 54MBit/s can be set up to 27dBm.

Hi,

I'l try to do the math....

For Germany the EIRP limit is: .... 27dBm

/interface wireless info> country-info germany
ranges: 2402-2482/b,g,gn20,gn40(20dBm)
2417-2457/g-turbo(20dBm)
5170-5250/a,an20,an40,ac20,ac40,ac80,ac160,ac80+80(23dBm)/passive,indoor
5250-5330/a,an20,an40,ac20,ac40,ac80,ac160,ac80+80(20dBm)/dfs,passive,indoor
5490-5710/a,an20,an40,ac20,ac40,ac80,ac160,ac80+80(27dBm)/dfs,passive

Subtracting the antenna gain 7.5dBi to find the radio TX power, counted as 8 dBi (we lose 0.5 dBi because RouterOS only accepts whole numbers!) gives 27dBm-8 dBi= 19dBm
The real transmitted total EIRP is 19dBm+7.5dBi= 26.5 dBm
Setting the TX power on the radio above 19dBm is illegal in Europe.

30 dBm limit in Europe is for devices that comply with TPC only!
"Transmit power / Power density: Max. 1 W e.i.r.p. Max. 50 mW/MHz e.i.r.p. density in any 1 MHz band. WAS/RLANs operating in the band 5470 - 5725 MHz shall either employ transmitter power control (TPC), which provides, on average, a mitigation factor of at least 3 dB on the maximum permitted output power of the systems; or if transmitter power control is not in use, the maximum permitted e.i.r.p. and the corresponding e.i.r.p. density limits shall be reduced by 3 dB. "
https://en.wikipedia.org/wiki/List_of_WLAN_channels

Thanks for the detailed information. Then everything is correct. I overlooked the TPC requirement.