Re: [Discuss-gnuradio] ADC questions

[Eric Blossom]

On Tue, Sep 23, 2008 at 05:04:54PM +0200, Sebastiaan Heunis wrote:
> Hi
> 
> I have a few questions to ask about the ADC if anyone could please
> help me?  I know that it has a 12-bit output, so our output is between
> 0 and 4095.  I would just like to know how this ADC input gets
> converted after leaving the adc_interface block in the FPGA.  In other
> words, how are positive and negative numbers represented, etc?  The
> FPGA converts the 12bit input to a 16bit output.  What is done to get
> it from the 0-4095 input to a 16bit output with + and - numbers?
> 
> Thank you very much.
> 
> Sebastiaan

See especially pages 8 and 9 of

  http://gnuradio.org/trac/attachment/wiki/UsrpFAQ/USRP_Documentation.pdf


Negative numbers are 2's complement.

Eric