Re: [Discuss-gnuradio] Question on FFT (Josh Blum)

2012-08-20 Thread Josh Blum 


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

 
 
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Re: [Discuss-gnuradio] Question on FFT

2012-08-17 Thread Josh Blum 


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

 Best Regards,
 Sam
 
 
 
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Re: [Discuss-gnuradio] Question on FFT

2012-08-17 Thread mleech 
 

On 17 Aug 2012 14:45, 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. 


 Best Regards,
 Sam

Because there's no negative frequency component
in your sample stream. 

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