On Wed, Jun 28, 2006 at 06:00:13AM +0000, paul munro wrote:
I have updated from CVS and re-recorded a new file using complex types and
the gain set to 20.
LabView is able to read in any type, so I have defined it to read single
precision floats (assuming the first 32 bits are I and the second 32 bits
are Q). I have also read straight into a complex type and obtain the
I now have I and Q values as I should. The values are in the range of
10^-41. Has anyone looked at the sampled values from the USRP before??
Why don’t you start with something like
gnuradio-examples/python/usrp/usrp_oscope.py which will show you what
we think the values are. [Sorry, no experience with LABVIEW.]
./usrp_oscope.py -g 20
Or if you’ve got octave or matlab installed, set the path for that
tool to include gnuradio-core/src/utils (take a look in that
directory). For octave edit ~/.octaverc and put this line in it:
octave:1> d = read_complex_binary(‘name_of_file.dat’, 1e6);
I am using the basic daughter board with no front end. I want to check that
these values are reasonable.
If you’ve got a signal generator, try connecting a 10 MHz signal with
a peak to peak amplitude of about 0.5V to the RX-A or RX-B inputs on
the Basic Rx daughterboard.
Then try one or both of these:
./usrp_fft.py -f 10M -g 20
./usrp_oscope.py -f 10M -g 20
D Shens tutorial mentions the PGA amplifies
the signal to a dynamic range of ±1???
I want to make sure the values are ok before moving on the next stage.
The values that you’ll see from usrp.souce_c(…) are in (-1.0, +1.0).
The smallest value you’ll see is about +/- 3e-5 (== 1.0/32768).
If you’re seeing 1e-41 I think you’ve still got a problem with
LABVIEW’s handling of binary input values.
The -g option sets the gain of the PGA. On the Basic Rx
daughterboard, the gain ranges from 0dB to 20dB by 0.1 dB steps.