TX gain control doesn't work on WBX+USRP2

GNU Radio
1

Hi all,

I got this issue when I test my own code. So I measured the transmit
power using a spectrum analyzer and ‘uhd_siggen_gui’ example in UHD.

I tested the following settings:

sudo uhd_siggen_gui -x 100k -g 0 -f 904M
sudo uhd_siggen_gui -x 100k -g 20 -f 904M

But the transmit power does not change over these changes.
Is there any clue on this issue?

FYI, I’m using the UHD version of 003.005.001.

I’m so looking forward to any help!

Thanks,
Yong