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Re: [Discuss-gnuradio] bandwidths< 400Khz no longer work with USRP2

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] bandwidths< 400Khz no longer work with USRP2
Date: Tue, 16 Nov 2010 21:13:27 -0500
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20101103 Fedora/1.0-0.33.b2pre.fc14 Thunderbird/3.1.6

On 11/14/2010 02:28 PM, Marcus D. Leech wrote:
I did a "git pull" for both UHD GnuRadio yesterday.  I'm on the "next"
branch for gnuradio, and on
  "master" for UHD.

Since doing a rebuild yesterday, bandwidths below 400KHz no longer work
on the USRP2.

I did a test with a dead-simple flowgraph:

UHD single source-->multi-const x 32767-->FFT

For bandwidths>= 400KHz, the resulting FFT, with my existing RF
front-end with 40dB gain feeding
   the BASIC_RX on my USRP2, the FFT looks just fine (showing a level
around -40dB).

But anything below 400KHz bandwidth (I tried various bandwidths between
200KHz and 400KHz),
   produces an FFT with nothing useful in it, and a "level" around -400dB.

This used to work just fine below 400KHz. What happened?

So, nobody has answered my question yet.

Even with the "latest and freshest UHD (master) and GnuRadio (next)", Rx bandwidths below 400KHz don't appear to work correctly on a USRP2
  with UHD, giving a flat-line at -410dB in the FFT display.

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