Switching between RX and TX - N210

[Summer 2021]

Hello everyone, 

I’m currently using an N210 with the Basic RX/TX cards and trying to send and receive FT8 messages using gnuradio and wsjt-x. I have successfully completed this but have noticed some issues that I haven’t been able to figure out. 

First, I’m having trouble figuring out how to use the SDR in half-duplex mode. Currently both the usrp sink/source blocks are set to TX/RX mode in gnuradio, however when I switch from receiving to transmitting I have verified that the SDR is still receiving signals and in fact I’m receiving the signal I’m putting out. What I’m trying to accomplish is that when I go to transmit, the receiver turns off and no data comes through on the RX side. 

Second, I’m having some issues with the timing of the audio being sent from wsjt-x to my SDR through gnuradio. I have found that when using rational resamplers and selector blocks in my GRC set up that the audio will be delayed and cut off when sending it from wsjt-x to the SDR. Additionally after successfully transmitting for some time and then turning off the transmit option and waiting a while, when I try to transmit again the audio is delayed and cut off in getting to the SDR. 

Thanks in advance.