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Re: [Discuss-gnuradio] New to gnuradio - Complex sampling question - urg
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] New to gnuradio - Complex sampling question - urgent |
Date: |
Sat, 13 Jun 2009 15:23:03 -0700 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Sat, Jun 13, 2009 at 02:31:59AM +0200, Sebastiaan Heunis wrote:
> Jason
>
> From what I've picked up, you need two external sampled signals to get
> an I-Q signal. With the TV tuner daughterboard, you automatically get
> two signals. You just need to set the mux accordingly. When you use
> a BasicRX, you need to feed the same signal to both inputs and use a
> mux value of 0x32103210.
If you use the standard interfaces, you don't have to do anything. You
always get a valid complex baseband signal.
The daughterboard code knows which boards have a single real output
and which have quadrature inputs. In the single real case (e.g.,
TVRX), the library configures the mux such that it feeds the single
input into the I side of the DDC and connects a constant zero into the
Q side. The output of the DDC is always complex. In the case of
daughterboards with quadrature output, one input is connected to the
I input of the DDC and the other is connected to the Q input.
See http://gnuradio.org/trac/wiki/UsrpRfxDiagrams
Eric