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

Marcus D. Leech mleech at ripnet.com
Tue Dec 2 08:59:02 EST 2014


On 12/02/2014 02:03 AM, WuHaoyang wrote:
> ‍ 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.
>
That absolute maximum aggregate sample-rate that can be supported over a 
single 1GiGe link is 25Msps, so if you're trying to stream two channels
   at those rates, it won't work.  This is just straight 1GiGe link 
occupancy.


>
>
> ------------------ 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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>>
>>
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>
>

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