Re: [Discuss-gnuradio] IF sampling in ISM band

[Eric Blossom]

On Tue, Jul 08, 2008 at 10:16:53AM +1000, Phaysal Khan wrote:
> 
> Hi List,
> Just re-stating the issues I am having with capturing IF samples of an RF 
> signal: I am trying to sample a 16MHz wide spectral content from a signal, 
> originally centered at 2.414 GHz. I am using RFX2400, gnuradio 3.1.2 and 
> using following command:
>  
> python usrp_rx_cfile.py -f 2404.5M -s --no-hb -8 -N 40000 data1.dat
>  using "-f 2404.5M" to get IF (downconverted) signal centered at 10MHz.
>  using "-s --no-hb -8" to be able to capture 16MHz wide bandwidth.
>  I am having following issues:
> 1. I am getting a downconverted signal centered at zero freq and not at 10MHz 
> which I expected.
> 2. I can see downconverted signal's spectrum to be only +/-4MHz wide, and not 
> +/-8MHz.


In the trunk (sorry, I didn't take time to build 3.1.2), when I do
this, I see 16MHz of spectrum:

  address@hidden ~]$ usrp_fft.py -8 -f 92.1 -d 4

How do you _know_ you're not getting +/- 8MHz?


How wide is the signal that you want offset by 10MHz?

Eric

16MHz-wide-fft.png
Description: PNG image