Universal Software Radio Peripheral (USRP) |
"uO" stands for "USRP overrun" and means that the host PC could not receive data from the USRP as fast as new samples were captured off the air. This message is produced by usrp_source blocks.
"uU" stands for "USRP underrun" and means that the host PC could not produce new samples as fast as the USRP sended them out. This message is produced by usrp_sink blocks.
In both cases, these messages mean that data was lost and discontinuitites were introduced into the signal. The following options reduce the overruns/underruns:
If the "uO" or "uU" messages appear right away when the simulation is started, but no new overruns occur, it is highly likely that these messages are incorrect and no overrun occured at all. This is a known bug in the USRP.
This happens when a USRP board with empty daughterboard slots is connected to the computer. Put a daughterboard into every slot or ignore this message.
This is a known bug, the cause has not been found yet. This seems to happen most often when we are dealing with unconfigured USRPs without firmware/bitstream. Disconnecting and reconnecting the USB cable of the USRP and issuing clear mex; on the MATLAB command promt often helps.
libusrp, the library which is used to talk to the USRP, configure its daughterboards etc., is released by the Free Software Foundation/GNU Radio under the GNU General Public License (GPL). Speaking simplified, it may therefore not be linked with any binary libraries for which the source code is not freely available to everyone. Since Simulink-USRP links against MATLAB libraries, which are only available in binary format, we are not allowed to give out binary files for Simulink-USRP.
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