Hi, I'm using gnuradio 3.7.12 and rfnoc-devel commit 1908672.
I'm trying to use both daughter boards on the x310 each at full duplex (that is, I will have 2 independent tx paths and 2 independent rx paths). So far I have accomplished this by using the UHD: USRP Sink/Source blocks and setting them to 2 channels, selecting the appropriate antennas, and specifying a subdev spec of A:0 B:0. The flowgraph works perfectly sending and receiving 2 sets of data simultaneously. However, I need to have the same capability when using the RFNoC blocks. I've attempted to use 2 RFNoC radio blocks, one set to Tx, 2 channels, and the other set to Rx, 2 channels, however the block's parameters have only a radio select of A or B unlike the usrp source's subdev spec, so this setup does not appear to work no matter what configurations I try. Am I mistaken about what the 2 channels refers to here? I did finally get an RFNoC setup that works by using 4 RFNoC radio blocks (2 for transmit with radio select A, B respectively, and 2 for receive with radio select A, B respectively). However, with this setup I get tons of underflow "U" in the console. Curiously this happens even when using the DMAFIFO as ettus recommends so I'm not sure what's going on. My flowgraph is attached showing this setup. (A quick note on why I want to use the rfnoc blocks, apparently the uhd usrp sink block now automatically includes a DMAFIFO in the tx chain to deal with the underflow issue caused by tcp flow control, however for my application the depth/size of this fifo is much too large and causing massive delays, I've found that by reducing the depth I can minimize my delay and I'll only get underflows on flowgraph startup which I assume is due to the tcp slow start phase before backoff occurs. All this to say, if there is a way to adjust the dma fifo depth from the usrp sink blocks I'd gladly use that instead). Thanks, Mike
test_dual_fullduplex_x310.grc
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