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Re: [Discuss-gnuradio] GRC+USRPx file sink problem
From: |
Marcus D. Leech |
Subject: |
Re: [Discuss-gnuradio] GRC+USRPx file sink problem |
Date: |
Wed, 18 Aug 2010 15:26:38 -0400 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.11) Gecko/20100720 Fedora/3.0.6-1.fc12 Thunderbird/3.0.6 |
On 08/18/2010 01:41 PM, David Evans wrote:
> Hi,
>
> GRC Setup (used with RFX and WBX cards)...
>
> USRP1 ---to---> FFT Graphical sink (shows signal spectrum as expected)
> and ---to---> Complex to IShort -----to----> File Sink (signals are
> dumped
> to disk as expected)
>
> USRP2 ---to---> FFT Graphical sink (shows signal spectrum as expected)
> and ---to---> Complex to IShort ----to----> File Sink (******file is
> all
> zeros******)
>
> Tried with 3.3.0 and git 3.3.1, and on three different installations/USRPs.
> Basically zero output with USRP2.
> USRP2 works fine with python scripts eg, usrp2_fft.py with --output-shorts.
>
> Any ideas please?
>
> Dave
>
>
My guess is that with USRP2, samples are scaled -1.0 to 1.0. Which
means that a straight conversion to
a short integer is going to yield zero most of the time. Try putting
a multiplier block in front of your
file sink--maybe scale those -1.0 to +1.0 to +/- 32767.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org