# Sampling Bandpass Signals With less than Nyquist frequency

Started by March 28, 2001
 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
 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