[USRP-users] X310 + 2 CBX daughtercards strange behaviour

Ian Buckley ianb at ionconcepts.com
Tue Sep 23 11:00:00 EDT 2014


Herve,
Your configuration is quite a common one (that generally works well) so there's something more specific than just that collection of hardware going on here.

I think at this point it would be very helpful if you can attach your GRC flowgraph to a post and also describe in some detail how you have cabled your X300 to the signal source so that the chances of reproducing this independently are maximized.

-Ian


On Sep 23, 2014, at 6:07 AM, boeglen herve via USRP-users <usrp-users at lists.ettus.com> wrote:

> Hi all,
> 
> I didn't get any answer to this email so I send it again :-)
> 
> Does anybody on the list use a X300 or X310 equipped with 2 radio boards and 10Gbit interface ? If so, have they already tested a simultaneous TX or RX?
> 
> This problem looks to me as if the second daughter card is not configured properly.
> 
> Thank you for your answers.
> 
> Best regards
> 
> Hervé
> 
> -------- Original Message --------
> 
> Subject:	Re: [USRP-users] X310 + 2 CBX daughtercards strange behaviour
> Date:	Sat, 20 Sep 2014 09:35:19 +0200
> From:	boeglen herve <herve.boeglen at univ-poitiers.fr>
> To:	"Marcus D. Leech" <mleech at ripnet.com>
> Cc:	Mike Jameson <mike.jameson at ettus.com>, <usrp-users at lists.ettus.com>
>  
> Hi,
> 
> I know pretty well the throughput limit of the 1Gbit interface, that's why I  use a 10 Gbit one :-) It's really impressive since it holds the 100Ms/s using both channels. My machine runs a Core I7 2600k + 12 Gbyte RAM on Ubuntu 14.04 64 bit (3.13 kernel, MTU set to 9000!). I use the latest firmware with GNURadio 3.7.5.
> 
> Concerning my problem, RF 0 channel (first CBX) has a noise floor around -100 dB on the spectum scope whereas RF 1 (second CBX) goes up to -60 dB. However my settings are the same for both channels.
> 
> When mentioning the bandwidth, It was to describe the behaviour of the signal on RF 1 (wider noise bandwidth).
> 
> Another noticeable difference between the two channels is that you get a -55dB spike at 0Hz on RF 1. When performing the Wifi test, everytime a packet enters, RF 1 channel's noise floor increases around -60dB (over the 50MHz bandwidth). Really weird...
> 
> Best regards
> 
> Hervé
> 
>  
> On Fri, 19 Sep 2014 17:16:20 -0400, Marcus D. Leech wrote:
> 
> Hi Markus and Mike, Thank you for your answers. It does not change anything whether you specify the subdev or not. Markus: yes everything is wired properly. Concerning the last email, I used a BladeRF as a generator (0dBm + 30dB attenuator). Here is another test with Wifi and as you can see from the two spectrum scopes (upper is RF 1, lower RF 0), RF 1 reception bandwith seems to be larger than for RF 0 (however it's set to 20MHz for both channels). I have a second X310 with the same daugthercards and I get the same behaviour... Is there a way to use just RF 1? I hope that going to sleep is going to help me to find an idea to solve the problem :-) Best regards Hervé
> The bandwidth setting doesn't do anything on the CBX card--it's only 
> used to set the analog bandwidth between the cards baseband/IF output, and
>    the ADC.
> 
> The bandwidth delivered to the host depends, in this case, on the 
> specified sample rate.
> 
> What type of host interface are you using in this case?  From the 
> spectrum plots, it looks like you're asking for two channels of 25Msps 
> each, which
>    will not "fit" over 1GiGe at 16-bit samples.
> 
> Do you get any 'O' being output while you run this flow-graph?  What 
> type of computer?
> 
> 
> 
>  
>  
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20140923/6a0beb26/attachment-0002.html>


More information about the USRP-users mailing list