[Discuss-gnuradio] Multiple USRP1 and UHD

[Chadwick, Andrew]

Hello list,

I have two USRP1s and four DBSRX2 daughterboards. I would like to synchronise the USRPs, to build a coherent, sample aligned, four channel receiver (inputs from four separate antennas). I had hoped I could do this by modifying and connecting the boards as described here:

http://gnuradio.org/redmine/wiki/1/USRPClockingNotes

http://gnuradio.org/redmine/wiki/1/MultiUsrp

And then modifying the usrp_multi code to work with UHD. If this approach works, it looks like I have to replace the lines (amongst others):

u1 = usrp.source_s (1, decim, nchan, gru.hexint(mux), mode,fpga_filename="multi_2rxhb_2tx.rbf" )

u0 = usrp.source_s (0, decim, nchan, gru.hexint(mux), mode,fpga_filename="multi_2rxhb_2tx.rbf" )

But, how do I set the mux and mode values if I replace these with instances of uhd.single_usrp_source? And is the multi_2rxhb_2tx.rbf image likely to work still with UHD? I'm pretty new to this so any pointers, or suggestions for a better approach, appreciated...

I'm also having problems with the UHD multi_usrp_source, trying to use this in GRC for some initial experiments with the boards unsynced. With Num Mboards = 2, device addresses of either “serial=XXXXXXXX, serial=YYYYYYYY” or “name=usrp_master, name=usrp_slave” (either way round) and the same subdev spec “A:0 B:0” for both, I can find the first board but not the second. Maybe I’ve just got the syntax wrong or is there another problem?

  File "/home/ac2/grc/top_block.py", line 70, in <module>

    tb = top_block()

  File "/home/ac2/grc/top_block.py", line 40, in __init__

    self.uhd_multi_usrp_source_0.set_subdev_spec("A:0 B:0", 1)

  File "/usr/local/lib/python2.6/dist-packages/gnuradio/uhd/uhd_swig.py", line 887, in set_subdev_spec

    return _uhd_swig.uhd_multi_usrp_source_sptr_set_subdev_spec(*args, **kwargs)

RuntimeError: vector::_M_range_check

With Num Mboards = 1, I get past this point but not much further:

thread[thread-per-block[0]: <gr_block uhd multi_usrp source (3)>]: cannot get this property

  in void usrp1_impl::mboard_get(const wax::obj&, wax::obj&)

  at /home/ac2/gnuradio-uhd/uhd/host/lib/usrp/usrp1/mboard_impl.cpp:329

What's going wrong here? Two separate single sources works fine. I’m using a fairly recent build, source downloaded from git on 3^rd Jan, and Ubuntu 9.04 for what that’s worth.

Thanks,

Andy

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