B11 Tx Power settings Total vs per channel/polarity


#1

If my license allows for 20 dB of Tx power (56 total EIRP and a 36 dBi antenna), then what do I make the Tx Power setting in the radio?

If I make the Tx power setting equal to 20 dBm, then on the dashboard I see each chain at 6 dB less.

If I move the Tx power setting up to 26 dBm, then I see 20 dBm per polarity on the dashboard, again 6 dB less.

What’s the correct and legal answer? I understand you essentially add 3 dB when you add a second antenna for MIMO, but how does it work in this situation? For this question, I’m using 2x 80 MHz channels running 1.4.6 firmware.

Thanks for the clarification,
Kevin


#2

So when you’re using 2xXX channels, your TX power is split between the two chains – 1 and 2 or 3 and 4. So on 2xXX you subtract 3 per chain.

Here is some additional information that helps explain this:

http://backhaul.help.mimosa.co/backhaul-faq-maximum-tx-power
http://backhaul.help.mimosa.co/backhaul-faq-maximum-tx-power-details


#3

So the Tx Power should be set to the license level and then the radio will power each chain at 6 dBm less so that the overall power will be at the license level?

Sorry for my ignorance, but that is my reading of your two links.


#4

If the transmit power is split when in dual channel mode, then maybe you set the Tx power to be 3 more than what you are licensed for?

An example under the B11 section in the first link above would be really helpful.


#5

Sorry for the confusion on this guys! I’ll make sure that we add additional information for this.

As for your TX power settings, you should set your radio to the correct TX power that is sent on your coordination form. So if you are supposed to be set at 20TX power, your Channel and Power page should also be set to 20TX power.