Reply by Emerson Tan 95-28046 ●March 30, 20012001-03-30

Hi! What you like to do is similar to what AM radios do. AM music are
located somewhere between Fmin and Fmax. The radio "tunes" or shifts the
bandpass signal to baseband so that it can send it to the speaker. To
move it back to Fmin and Fmax, the radio "modulates" the signal.
Regarding your filtering operation, it would be similar except for
errors. You have to watch out for those errors.

--emer

On Wed, 28 Mar 2001, Kiran Gunnam wrote:

> Hello,
> I have some questions on sampling the bandpass signals.
>
> If I have a analog band pass signal with the frequncy range Fmin to
> Fmax,is it possible to sample with 2*(Fmax-Fmin) instead of The
> Nyquist frequncy ,2*Fmax?
>
> Is it sufficient to use a bandpass filter to reconstruct the analog
> signal from the sampled signal?
>
> If I use a filtering operation on the sampled signal,is it equivalent
> to the same operation on a signal sampled with Nyquist frequncy?
>
> Is there any difference in sampling narrowband pass signals and wide
> band pass signals?
>
> And can some one point out the resources on this topic which give the
> details of system design and mathematical details?
>
> Thanks in advance.
>
> Regards
> Kiran >
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Reply by Bill Zimmerman ●March 29, 20012001-03-29
Kiran > Hello,
> I have some questions on sampling the bandpass signals.
>
> If I have a analog band pass signal with the frequncy range Fmin to
> Fmax,is it possible to sample with 2*(Fmax-Fmin) instead of The
> Nyquist frequncy ,2*Fmax?
>
Yes, this will translate the down to baseband. Normally people perform
complex sampling (in-phase and quadrature) to ensure an accurate
representation.
> Is it sufficient to use a bandpass filter to reconstruct the analog
> signal from the sampled signal?
>
Once you sample the data, it no longer has the original freq content. In order
to reconstruct the signal, you would need to bandshift the data.
> If I use a filtering operation on the sampled signal,is it equivalent
> to the same operation on a signal sampled with Nyquist frequncy?
>
No, the frequency content has been shifted. However, it is usually easier to
design an equivalent filter that can be applied to the basebanded signal.
> Is there any difference in sampling narrowband pass signals and wide
> band pass signals?
>
Don't think so.
> And can some one point out the resources on this topic which give the
> details of system design and mathematical details?
>
You probably want a book on communication theory and one on spectral
analysis.

Ex.
An Introduction to Random Signals and Communication Theory, B.P. Lathi,
Int'l Textbook Company

Discrete-Time Signal Processing, Alan Oppenheim & Ronald Schafer,
Prentice Hall
> Thanks in advance.
>
> Regards
> Kiran
Bill Zimmerman
Good mathematics promotes Intellectual Economy by helping us
understand more while obliging us to memorize less without violating .
Einstein's Dictum: "Everything should be as simple as possible,
but no simpler." - W. Kahan

ManTech (954)929-8604 Voice
One Oakwood Blvd. Suite 180 (954)925-0205 FAX
Hollywood, FL 33020


Reply by Kiran Gunnam ●March 28, 20012001-03-28
Hello,
I have some questions on sampling the bandpass signals.

If I have a analog band pass signal with the frequncy range Fmin to
Fmax,is it possible to sample with 2*(Fmax-Fmin) instead of The
Nyquist frequncy ,2*Fmax?

Is it sufficient to use a bandpass filter to reconstruct the analog
signal from the sampled signal?

If I use a filtering operation on the sampled signal,is it equivalent
to the same operation on a signal sampled with Nyquist frequncy?

Is there any difference in sampling narrowband pass signals and wide
band pass signals?

And can some one point out the resources on this topic which give the
details of system design and mathematical details?

Thanks in advance.

Regards
Kiran