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

[Eric Blossom]

On Mon, Jul 07, 2008 at 05:27:40PM -0700, Eric Blossom wrote:
> 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


I note that you're not specifying -d 4 to set the decimation rate.


> >  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