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Re: [Discuss-gnuradio] reading two rx channels on usrp2
From: |
Johnathan Corgan |
Subject: |
Re: [Discuss-gnuradio] reading two rx channels on usrp2 |
Date: |
Wed, 27 Jan 2010 11:07:37 -0800 |
On Wed, Jan 27, 2010 at 10:54, Tom Gross <address@hidden> wrote:
> Johnathan, the custom FPGA firmware you describe sounds like it might
> be perfect for what we want to do, provided it's not impossible to
> demux the data stream.
It's straightforward. Just use gr.deinterleave(gr.sizeof_gr_complex)
after the usrp2.source_32fc block, and attach two separate complex
input block chains to outputs 0 and 1 of the deinterleaver. Also, the
minimum decimation rate becomes 8 instead of 4 (this isn't checked
for.)
> I haven't seen any usrp2 FPGA sources (they
> don't appear to be in either the 3.2.2 or 3.3.3 tarballs) - I guess
> this means I need to figure out the new "git" stuff...
The FPGA code is not distributed as part of GNU Radio (it's a product
of Ettus Research). It's currently hosted inside the gnuradio.org
repository, though that will be changing. For now, though, the only
git fu you need to know is:
$ git clone git://gnuradio.org/gnuradio
...to create your own complete repository (assuming you already have
git installed.)
> it sounds like I will need to get a Xilinx compiler to build them,
> once I find them.
Yes. FYI, the USRP2 FPGA requires the full version of the Xilinx ISE
tools; the free version won't work. Also, you specifically need
release 10.1 with SP3. There are currently problems synthesizing even
the standard image with newer versions of the tools.
Johnathan