USRP producing samples larger than 2^8

GNU Radio
1

Hi,

Should I get samples with a magnitude > 128 from the USRP no FPGA gain?
I believe the answer is no. Take a look at these plots of the data I
am getting (plot of real portion only):

http://img157.imageshack.us/img157/8648/plot1gi6.gif

http://img245.imageshack.us/img245/8528/plot2fp1.gif

I collected the data using this method:

./usrp_rx_cfile.py -d 16 -f 1575420000 -g 0 -N 4000000 file.dat

Furthermore, I created a test jig which wrote USRP output to stdout and
verified these spikes are not in the binary file or the binary file
reader. I’m using the DBSRX with a GPS antenna and a low noise
amplifier.

Thank you!

Chris

2

Chris S. wrote:

Hi,

Should I get samples with a magnitude > 128 from the USRP no FPGA gain?
I believe the answer is no. Take a look at these plots of the data I
am getting (plot of real portion only):
ADC is 12 bit => +/- 2^11
all processing blocks are 16 bit
So if there is any fpga gain (for example in the DDCs)
You can get +/- 2^15 values

Greetings,
Martin