[USRP-users] Rx/Tx Loopback

Rob Kossler rkossler at nd.edu
Wed Apr 1 23:41:12 EDT 2015


On Wed, Apr 1, 2015 at 11:38 PM, Marcus D. Leech <mleech at ripnet.com> wrote:

>  On 04/01/2015 11:35 PM, Rob Kossler wrote:
>
>  ok.  I'll try that.  Thanks.
>
>
>  Yes, the streams are going to the same physical device.  But no 1 PPS
> input.  My intention is to use X310 internal PPS.  I think the GRC UHD
> sink/source setting for clock source is "default".  I'm assuming that means
> internal PPS.
>
>
> On Wed, Apr 1, 2015 at 11:04 PM, Marcus D. Leech <mleech at ripnet.com>
> wrote:
>
>>  On 04/01/2015 11:00 PM, Rob Kossler wrote:
>>
>>  I don't recall any error message with the low sample rate.  But, I was
>> also using higher rates like 1 MS/s and 10 MS/s also.
>>  Rob
>>
>>   May just be a buffering elasticity issue.
>>
>> Try putting something like a multiply-const block between them, with a
>> constant of 1.0.  Just to put some buffering in place.
>>
>> These streams are going to the same physical device, yes?  And it has a
>> 1PPS input?
>>
>>
>>
>>  On Wed, Apr 1, 2015 at 10:58 PM, Marcus D. Leech via USRP-users <
>> usrp-users at lists.ettus.com> wrote:
>>
>>>   On 04/01/2015 05:57 PM, Rob Kossler via USRP-users wrote:
>>>
>>>   I would like to run a simple Rx to Tx loopback using gnuradio
>>> companion with my X310.  The attached flowgraph contains two blocks, a UHD
>>> source and UHD sink, which are directly connected to each other on each of
>>> the 2 channels.
>>>
>>> When I run it, I get numerous "L" indications.  To me, this indicates
>>> that I'm not delivering the samples to the Tx Streamer when it wants them.
>>> Perhaps the start times for RX streaming and TX streaming need to be
>>> specified?  If so, can this be done from GRC?
>>>
>>>  Thanks.
>>>  Rob
>>>
>>>
>>>   _______________________________________________
>>> USRP-users mailing listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>>  The only thing I notice is that you've specified a really-low sample
>>> rate, one which I'm thinking the X310 cannot support, did you get any error
>>> messages
>>>   to that effect when it's running.
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users at lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>>
>>
>>
>  YOu have "don't sync" on the sink, and "unknown PPS" on the source.
>
>
>  Yes, those are the sync options.  Since there is only one device, I only
selected "unknown PPS" for one of the two streamers.  Is that correct?
Rob
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