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

WuHaoyang wuhaoyang at bupt.edu.cn
Tue Dec 2 01:35:40 EST 2014


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"?

3. What does "L" & "S" mean exactly?

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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]回复:  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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------------------
吴浩洋 北京大学
高能效计算与应用中心
2013级 计算机系 博士
电话:+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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