Hi, I realized that in my packet loopback example, I didn't connect any of the QT GUI sinks after the USRP source. The updated flow graph is attached in screenshot0. After I connected them, I ran the packet loopback example on my MacBook Air using one B210 board with TX/RX and RX2 antennas attached and got the results attached in screenshot1, but still received underruns as printed out in the terminal in the bottom left corner. I also ran the example with two B210 boards with a TX/RX antenna on one and a RX2 antenna on the other and got slightly different results. Instead, the third graph was just a straight horizontal line and still ran into underruns. I also ran the same program with a Raspberry Pi 4 with one B210 board and got similar results. So I don't think it's an issue concerning computer power.
Also, I was wondering what you meant by "for a loopback flow at low rates you may need to alter the internal buffer sizes in your flow-graph to prevent TX starving for samples because the RX buffers are still filling. But this is not a distinctly USRP problem and has more to do with GnuRadio". How would I alter the internal buffer sizes and what would I need to change it to?
Are there any other suggestions you have for me to successfully get this loopback example running?
Thanks!