[Discuss-gnuradio] Gain Range error

[amarnath alapati]

hi friends, 
 When I tried to print the Transmitter gain range by the following commands, The output is as followss,

address@hidden digital]# python benchmark_tx.py -f 2412M --show-tx-gain-range
>>> gr_fir_fff: using SSE
Tx Gain Range: minimum = 0, maximum = 0, step size = 1

1) Why is the gain Minimum and Maximum showing the same 0?
2) How to control the transmit power ? Should I use the --amplitude command?
3) can some one breif me on the controlling of transmitter power issue?

Thanks,
Amarnath