Usrp rev 4.1 question

Hello,

I’m still new at this. Please be patient with me.

I’m getting confused by the variances in docs and articles I can find on
the internet. I’m confused about the exact capabilities of the usrp,
and the Basic RXs that I have. I have a usrp rev 4.1 and two basic RX
boards (not sure about the rev), that were all purchased around June of
2006. My question is: is one of my Basic RXs capable of implementing
two receivers and outputting two complex signals, or is it only capable
of outputting one complex, or two real signals?

Thanks,
Hans

On Mon, Feb 12, 2007 at 05:52:43PM -0800, Hans G. wrote:

Hello,

I’m still new at this. Please be patient with me.

No problem :wink:

I’m getting confused by the variances in docs and articles I can
find on the internet.

Best bet is the list, the wiki, the doxygen documents, and the .h files.
We control the documents on gnuradio.org and gnu.org, but not those on
any other web site. YMMV.

I’m confused about the exact capabilities of
the usrp, and the Basic RXs that I have. I have a usrp rev 4.1 and
two basic RX boards (not sure about the rev), that were all
purchased around June of 2006. My question is: is one of my Basic
RXs capable of implementing two receivers and outputting two complex
signals, or is it only capable of outputting one complex, or two
real signals?

Each Basic Rx daughterboard can output two streams of complex.

What happens is that thought the DDC in the FPGA takes an I and a Q
input, and produces I & Q output, when used with the basic rx, we
configure the Rx Mux such that a constant zero is fed into the Q
inputs.

Most applications (such as usrp_oscope or usrp_fft) take a
-R command line option. Use -R A:0 for one of the
inputs, -R A:1

To use all 4 inputs simultanenously, look at the code in
look gnuradio-examples/python/multi-antenna/*.py

You’ll also probably want to take a look at the docs on the Rx Mux to
see how we’re routing stuff. See usrp_standard.h or
http://gnuradio.org/doc/doxygen/classusrp__standard__rx.html

/*!

  • \brief Set input mux configuration.
  • This determines which ADC (or constant zero) is connected to
  • each DDC input. There are 4 DDCs. Each has two inputs.
  • 
    
  • Mux value:
  • 3 2 1
  • 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
  • ±------±------±------±------±------±------±------±------+
  • | Q3 | I3 | Q2 | I2 | Q1 | I1 | Q0 | I0 |
  • ±------±------±------±------±------±------±------±------+
  • Each 4-bit I field is either 0,1,2,3
  • Each 4-bit Q field is either 0,1,2,3 or 0xf (input is const zero)
  • All Q’s must be 0xf or none of them may be 0xf

*/

Eric

Hans G. wrote:

is it only capable of outputting one complex, or two real signals?
The BasicRX has 2 analog signals coming in. You can use 1 as I and 1 as
Q, in which case you get 1 IQ signal going into the host. You can also
use them as individual real signals. In that case, each real signal
would be downconverted into an IQ signal, thus sending 2 IQ signals back
to the host machine.

Matt

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