[Discuss-gnuradio] Can I make USRP switch between speaking and muting?

[周崴]

 I want to send one ofdm symbol then mute during one symbol, and loop in that way.
I have tried to make the second symbol to be all 0+0j in baseband. But the output remains
an output noise which is not as low as requied. I think the RF always output something even
if the baseband gives him 0+0j.
Can I make the silent symbol as weak as background noise?