I'm trying to run gr radar on Ubuntu 18.04 using Gnuradio 3.8.2 and keep getting the following error when using the echotimer block with two USRP N210s:
Generating: '/home/user/Documents/tests/test_usrp_echotimer_cc.py'
>>> Warning: This flow graph may not have flow control: no audio or RF hardware blocks found. Add a Misc->Throttle block to your flow graph to avoid CPU congestion.
Executing: /usr/bin/python3.6 -u /home/user/Documents/tests/test_usrp_echotimer_cc.py
[INFO] [UHD] linux; GNU C++ version 7.5.0; Boost_106501; UHD_3.15.0.0-62-g7a3f1516
[INFO] [USRP2] Opening a USRP2/N-Series device...
[INFO] [USRP2] Current recv frame size: 1472 bytes
[INFO] [USRP2] Current send frame size: 1472 bytes
Using USRP Device (TX):
Single USRP:
Device: USRP2 / N-Series Device
Mboard 0: N210r4
RX Channel: 0
RX DSP: 0
RX Dboard: A
RX Subdev: WBXv3 RX+GDB
TX Channel: 0
TX DSP: 0
TX Dboard: A
TX Subdev: WBXv3 TX+GDBERROR_CODE_LATE_COMMAND
Setting TX Rate: 1000000
Actual TX Rate: 1e+06
[INFO] [USRP2] Opening a USRP2/N-Series device...
[INFO] [USRP2] Current recv frame size: 1472 bytes
[INFO] [USRP2] Current send frame size: 1472 bytes
Using USRP Device (RX):
Single USRP:
Device: USRP2 / N-Series Device
Mboard 0: N210r4
RX Channel: 0
RX DSP: 0
RX Dboard: A
RX Subdev: UBX RX
TX Channel: 0
TX DSP: 0
TX Dboard: A
TX Subdev: UBX TX
Setting RX Rate: 1000000
Actual RX Rate: 1e+06
set_min_output_buffer on block 3 to 524288
set_min_output_buffer on block 4 to 524288
set_min_output_buffer on block 5 to 524288
gr::fft: can't import wisdom from /home/user/.gr_fftw_wisdom
set_min_output_buffer on block 7 to 524288
set_min_output_buffer on block 8 to 524288
terminate called after throwing an instance of 'std::runtime_error'
what(): Receiver error ERROR_CODE_LATE_COMMAND
>>> Done (return code -6)
This happens when I use 2 USRPs transmit and receiving when using the gr-radar test_usrp_echotimer_cc.grc file (or any other grc file that uses the echotimer block for that matter). The grc file seems to work fine with one USRP in loopback. I'm guessing the "ERROR_CODE_LATE_COMMAND" happens when the receiver USRP needs a different waiting time to start. Any idea how to fix this? Any help is appreciated. Thanks
