Re: Question on FFT (Josh Blum)

GNU Radio
1

Hi Josh!

Thanks for reply. I change type from complex float to float but still I
found no negative frequency. I attached the GRC image. What should be
the
type of blocks to get both frequencies ?

–

Best Regards,

Sam

On 08/17/2012 11:45 AM, Sam mite wrote:

Hi All,

I wanted to work on FFT using gnuradio. I have a question. Why there is
only one frequency shown in plot ? why negative frequency is not being
displayed ? I have attached picture of GRC implementation and FFT plot as
well.

So, the blue color means complex floats. The signal source is not
producing sin(t), its producing e^jwt

-josh

2

On 08/18/2012 01:47 PM, Sam mite wrote:

Hi Josh!

Thanks for reply. I change type from complex float to float but still I
found no negative frequency. I attached the GRC image. What should be the
type of blocks to get both frequencies ?

The FFT plotter wont plot the negatives frequencies for a float stream.
Since the plot would be symmetric about 0, as Im{s(t)} == 0, it would
just be a waste of screen real estate.

-josh