[USRP-users] Can USRP X300 support 2*2 MIMO

Marcus D. Leech mleech at ripnet.com
Tue Dec 2 01:42:45 EST 2014


On 12/02/2014 01:35 AM, WuHaoyang via USRP-users wrote:
> Hello, thanks for your comments!
>
> 1. I'm very sure I've saved the correct complex data in a .txt file. 
> the complex data use "float32" format, each complex data has 64bits. I 
> did a lot of similar experiment with single antenna mode, so I'm sure 
> the file data is correct.
>
> 2. How can I specify the subdev spec accordingly (A:0 B:0), just add 
> "(A:0 B:0)" following the "Mb0: Subdev Spec"?
Just use:

A:0 B:0

In the subdev spec.

>
> 3. What does "L" & "S" mean exactly?
L = Late packet.   The packet arrived with a time-spec on it, but that 
time had already come-and-gone when the packet arrived at the USRP
S = Sequence error.  usually because the network interface is dropping 
packets

Are you doing this on a VM, rather than a naked hardware machine?


>
> ------------------
> Wu Haoyang
>
>
> ------------------ Original ------------------
> *From: * "usrp-users";<usrp-users at lists.ettus.com>;
> *Date: * Thu, Nov 27, 2014 06:46 PM
> *To: * "usrp-users"<usrp-users at lists.ettus.com>;
> *Subject: * Re: [USRP-users]??: Can USRP X300 support 2*2 MIMO
>
> A couple of comments:
>
> - Are you truly saving complex data in a .txt file? Usually .txt
> indicates something else. The same file->throttle->Freq Sink will show
> the correct spectrum, right?
>
> On 11/27/2014 04:05 AM, WuHaoyang via USRP-users wrote:
> > version information:
> > UHD version: 003.007.000
>
> - For X300 in particular, we have fixed a lot of things since 3.7.0. I
> recommend an update.
>
> > This is our flowgraph, Two "File Sources" include different time domain
> > waveforms that generated by ourselves. We try to send different signal
> > with two TX antennas simultaneously.
>
> To reiterate, please make sure the file data is correct.
>
> > Following picture is the configuration of USRP Sink module.
>
> - You shouldn't need to, but you might want to specify the subdev spec
> accordingly (A:0 B:0).
>
> > when this test case is executed, we can not see the correct wave in RX
> > end. It seems that only the signal in Channel0 has been send out.(we use
> > single RX antenna, not MIMO mode, to receive and save the TX wave, and
> > print the waveform using MATLAB).
> >
> > The following picture shows the front panel of X300,
> >
> > We can see the LED behave like this:
> > TX/RX: Red
>
> - Red means 'TX', so according to your pic, you *are* tx'ing on both
> channels.
>
> > REF: Green
> > PPS: Green, twinkle
> > LINK: sometimes Red, sometimes Green
>
> These are fine.
>
> > Also we can see a lot of characters "L" and "S" in GNU Radio control 
> panel.
>
> These are not good. I wonder if the MIMO setup is too fast... Is there a
> chance you could try running GNU Radio master branch?
>
> Cheers,
> M
>
>
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>
> ------------------
> ??? ????
> ??????????
> 2013? ???? ??
> ??:+86 15210831011
>
> Haoyang Wu
> PhD Candidate , Center for Energy-Efficient Computing and 
> Applications(CECA)
> School of EECS, Peking University
> TEL:+86 15210831011
>
>
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