Re: How to shift frequencies in a non-flat manner

Michel Rouzic wrote:
> Following somebody's advice, I'm making a topic to expose my problem
> without talking about possible solutions.
>
> But first of all I'd like to restrict this topic to solutions on how to
> implement frequency shifting (that doesn't involve performing a DFT and
> shifting bins), I don't want to hear about performing a time-domain
> convolution with a kernel that changes through time, or doing some
> stuff I don't understand to get my signal in the DC and the noise in
> the AC (although I'm sure it would be a very good solution), my goal is
> not only to find a solution to my problem but also to know at last how
> to do that precise thing.
>
> So here's the problem : I got a signal of about 10,000,000 samples of a
> chirp going from frequencies 0 to 0.5 (1 being the sampling frequency),
> surrounded by lots of noise. I want to flatten that chirp at some
> frequency, so I can bandpass filter it to get rid of the noise.
>
> Right now I got a lil problem with understanding negative frequencies
> and the Hilbert Transform, so that would be cool if we could keep those
> two concepts out of this topic, if possible. Thanks.

I saw an episode of 60 Minutes one time about fraudulent professional
schools. One of their producers carried a hidden camera into an
interview for a position at a nursing school. In the interview, the
"candidate" confessed to a horrible fear of blood and needles. The
school administrator smiled and said that would not be a problem!

Back to the subject, though. Please describe what you mean by "flatten
that chirp at some frequency", and then we might spare you the blood
and needles, if we can.

John

.

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