How many ways to determine signal frequency?

[TimMiller]

Hi,

Does anyone have idea on how to determine signal frequency?

I am a first year graduate student in biomedicine and previously studied some general engineering, not really very versed in mathematics. We have lots of data measured from human to analysis, including EEG, heart pulse and others.

I would like to know what is the appropriate method to determine the frequency of a signal? For example, if you know a person’s heart is beating regularly which a man could count, how to count it with machine?

Since I just started working in this area, I would like to gather as much information as possible to do a comparison. For example, I heard from people that Discrete Fourier Transform might be used to determine frequency. DFT is of course in the undergraduate curriculum, but how to do that?

What about wavelet transform? I frequently saw its name associated with image processing, but most of the signals we process, such as EEG, are 1-D rather than 2-D image data. Does wavelet also apply to 1-D data? Can it be used for frequency determination?

And what about other types of transforms such as discrete cosine transform and Hankel transform? I would very much like to know how many methods already exist there.

Sincerely wish someone could give a survey on this topic, particularly for 1-D data.



Tim

 

[decepticon]

I am sure there are biomedical instruments for this purpose.

As you may know, a signal (say a man's heart beat) will be composed of a number of sinusoids of harmonic frequencies with different weights to each frequency. To measure this we may connect the instrument measuring the heart beat to an appropriate transducer to convert the analog signal to analog voltage signal. Then we sample this signal using an ADC. Next we calculate the DFT using an FFT algorithm on the computer and (voila !) we will have our required frequency components.....

But as I said, there should be an instrument that performs these operations in a single step.