[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Discuss-gnuradio] OFDM behaviour of recent UHDs
From: |
Josh Blum |
Subject: |
Re: [Discuss-gnuradio] OFDM behaviour of recent UHDs |
Date: |
Mon, 15 Apr 2013 16:02:32 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 |
On 04/15/2013 03:39 PM, Vincenzo Pellegrini wrote:
> Hi everybody,
>
> I have been experiencing some difficulties in obtaining
> the same "signal clarity" performance that I used to have with
>
> uhd_003.004.000-f500b92
>
> when I tried to transmit the same samples of the same signal
> (also same usrp B100, same XCVR2450 front-end, same frequency =5.8GHz, same
> receiving device, same tx/rx antenna positions)
> with both:
>
> uhd_003.005.001
> and
> uhd_003.005.002
>
> at the following links you can find images of a DVB-T modulation analyzer
> exposed to both transmissions.
>
> www.pellegrini-radio.it/uhd_003.004.000-f500b92.jpg
> www.pellegrini-radio.it/uhd_003.005.002.jpg
>
> If you look at the MER value, a much poorer constellation quality is
> evident when operating with the newer UHD and its matched images.
> (no performance difference was noticed in this respect between
> uhd_003.005.001 and uhd_003.005.002).
>
> Has this been experienced before?
> As somethin changed in between that I should be aware of?
>
If 3.4.0 worked, I would definitely give 3.4.5 a try to see if any of
the patches or fixes could have inadvertently caused the issue. That
will at least narrow down which versions are causing the difference.
There was a fix to DSP scaling to prevent clipping. Its possible that
the power level is simply lower? What signal amplitude are you using,
and does doubling it solve the issue?
http://code.ettus.com/redmine/ettus/projects/uhd/wiki/ChangeLog#003004005
-josh
> my best regards to everybody
>
> vince
>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>