UHD: tx - sync via MIMO cable, rx - "We're marking it DONE"

Setup: Two USRP2 + WBX boards, one PC with Ubuntu 10.04, the latest gnruadio/next and uhd from the github. The PC hosts two PCI express GigEthernet cards, which are connected to the two USRP2s.

I'm using UHD to tx/tr with two boards simultaneously. I'm working with Multi USRP source and sink from the GRC. I have two problems in my examples:

1) The tx part works except for the synchronization. I have a MIMO cable and I though about using it for that. However, it seems that Multi USRP sink does not see the cable. Is it possible to use this cable for sync purposes? Alternatively, is there a way to get rid of the one of the GigE cards and get the data through the mimo cable to

the other device (I know that this is the original MIMO cable idea, it's just that I haven't heard about any successful attempts).

2) The receiver gives me this nasty "We're marking it DONE" error message, that a few people reported earlier. Before trying out some of the posted solutions, are there any solutions to the problem that do not require changing C code and recompiling the whole thing?

Thanks,

Veljko (By Veljko Pejovi)

Re: UHD: tx - sync via MIMO cable, rx - "We're marking it DONE"

The mimo cable has not been addressed in UHD ATM. To receive from multiple usrps in a synchronized manner, you will need to feed each PPS and reference input appropriately according to the following docs:

http://www.ettus.com/uhd_docs/manual/html/usrp2.html#hardware-setup-notes

In the flow graph, one of the blocks should be set to "sync on unknown pps". If the times across the usrps are not synchronized, then the stream request will probably fail and the usrps will not stream in unison.

-Josh ( Josh Blum)