Re: [Discuss-gnuradio] About the -ve represenation on FFT graph.

[Howard Wong]

Thanks for your kindly reply.

Can you explain more that, both sides from the center frequency of the 
input frequency has been cut by a low pass filter.

Doesn't a low pass filter allow the lower frequency to pass?

Thanks,
Rono




On 28/02/11 12:22, Josh Blum wrote:
> On 02/27/2011 07:57 PM, rono wrote:
> > Sorry if the question was re-posted.
> >
> >
> > Can anyone reply this entry level question?
> >
> >
> > In complex data representation such as the attached image by grc,
> > the LPF cut the frequency in both direction(+/- freq)
> > which the center frequency is 0Hz
> >
> > http://www.fungkai.com/~howie/sdr/complex_1_basefreq0.gif
> >
> > When I set the base frequency to a large positive value such as 10MHz,
> > the cutoff shows on both side apart from the center frequency too.
> The baseband frequency parameter only changes the value printed on the x
> axis. For example: If you had a usrp source tuned to frequency X, you
> would also set the baseband frequency to X ->  for display purposes.
>
> -josh
>
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