Tx-gain in gr-digital/ofdm/example/benchmark_tx.py


Does anyone here know what is the transmission power for USRP N210? I
searched the datasheet, it seems the maximum is about 20 dbm. But when I
run the code in gr-digital/ofdm/example/benchmark_tx.py, the tx-gain
range is from 0 db to 31.5 db.
I think it apparently could not be as high as 31.5 db, which is 1000w.
So anyone here know how to figure out the transmission power here? for
example , when I choose --tx-gain to be 30 db.

Thank you!