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Re: [Discuss-gnuradio] problem with simple test of USRP2+WBX

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] problem with simple test of USRP2+WBX
Date: Fri, 19 Nov 2010 10:03:36 -0500
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10

On 11/19/2010 03:13 AM, Steve Mcmahon wrote:
> Hello:
> I'm stuck, and I need some help.
> I'm running GNU Radio 3.3.0 on openSUSE 11.2. I have two USRP2 boards, each 
> with a WBX daughterboard, connected to two Intel PRO/1000 GT NICs, on eth1 
> and eth2. I'm using the "txrx_wbx_raw_eth_20100608.bin" firmware, not the 
> from-the-factory firmware. I made a simple flowgraph which connects an FFT 
> window to a USRP2 Source, tuned to 900 MHz at a sample rate of 3.125 MHz 
> (decimation factor 32). I input a 901 MHz sine from an HP signal generator 
> into the TX/RX connector on the WBX daughterboard. When I run the flowgraph 
> with the USRP2 Source set to eth1 (for the first USRP2), it runs fine, and I 
> see a nice clear tall spike in the FFT at 1 MHz. However, when I set the 
> USRP2 Source to eth2 (for the second USRP2) and re-run the flowgraph, I get a 
> spike at 901 MHz that is barely noticeable and greatly attenuated. What's 
> going wrong here? I used that second USRP2 a few weeks ago with a different 
> daughterboard and it ran fine, so I don't think that USRP2 is bad.
>  Is there something wrong with the WBX daughterboard? Am I doing something 
> wrong in GRC? Any ideas?
> Any help would be GREATLY appreciated.
> Thanks a lot!!
> Steve McMahon
What power level did you use for the signal generator?

The GaAs MMIC LNAs on these boards don't like high power input, and the
gate insulator
  will often go "phhhttttttt!" if you input more than -15dBm for any
length of time.

Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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