Re: [Discuss-gnuradio] Spectrum Analysis with FFT plotting

[Ujala Qasim]

Hi,

I am now getting the following plot, when I set my target_freq to 89MHz (another radio station), with center_freq in set_rx_freq() function to -5.75:

http://i695.photobucket.com/albums/vv318/ujalaqasim/bell.jpg

The decimation rate is 250 and the sampling frequency is at 256ksps.

I am getting a bell shape but it is not taking the entire length of the plot. What could be wrong?

On Mon, Jun 1, 2009 at 2:11 AM, Sebastiaan Heunis <address@hidden> wrote:

Ujala

I've never worked with the C++ interface to Gnuradio.  I considered
using it a year ago, but was warned not to since a lot of
functionality still lacked at that time.

You need to tell the TVRX db to mix your signal down from 106.2MHz.
So you have the TVRX db with an IF of 5.75MHz?  In that case you will
need to set your DDC to -5.75MHz.  This will mix everything down by
5.75MHz resulting in your signal sitting at DC.  You can decimate by
250 and you should have your FM signal at DC and sampled at 256ksps.

Sebastiaan