Re: [Discuss-gnuradio] USRP producing samples larger than 2^8

[Martin Dvh]

Chris Stankevitz 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
> 
> 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
> 
> 
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