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

WuHaoyang wuhaoyang at bupt.edu.cn
Tue Dec 2 02:03:10 EST 2014


‍ I'm doing this on a naked hardware machine, not VM. In  single antenna mode (using gigabit ethernet port), we can set the sample rate up to 20MHz. but when we try to use MIMO, we can see the "L" & "S" even when we set the sample rate under 1MHz.


 




------------------ Original ------------------
From:  "usrp-users";<usrp-users at lists.ettus.com>;
Date:  Tue, Dec 2, 2014 02:42 PM
To:  "usrp-users"<usrp-users at lists.ettus.com>; 

Subject:  Re: [USRP-users] Can USRP X300 support 2*2 MIMO



                   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]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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