Finding a specific amplitude-frequency in the time domain

In summary, The conversation discusses the use of FFT results on a signal to find specific frequencies and their corresponding time zones. The MATLAB code for applying FFT on a CSV file is also provided. The individual is seeking advice on how to specify the time when a specific low frequency with high amplitude occurs. The Short-time Fourier transform is mentioned as a potential method for this purpose.
  • #1
Behrouz
21
0
Hello,

I have a signal and got the FFT result of that. I have shown them both below along with the MATLAB code.

May I ask if there is any method to find the time zone(s) in the signal that a specific frequency has(have) happened?

The reason I'm asking this is that I want to specify the time that I had a (specific) low frequency with a (specific) high amplitude.
Code: 
%% apply fft on the csv and plot the result

nfft = length(M);

nfft2 = 2^nextpow2(nfft);

ff = fft(M, nfft2);

fff = ff(1:nfft2/2);

stem(abs(fff));

uc?id=1Ps_ewvEN6HIb2z9CS7gGiEnNI3GP4mts.png

uc?id=1W-38kvWD1hDHxxsU9rRDILzKHH8Wb8bP.png


Any advice would be greatly appreciatd.

Regards,
Behrouz
 

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Physics news on Phys.org

1. What is the relationship between amplitude, frequency, and time in the time domain?

In the time domain, amplitude refers to the magnitude of a signal at a specific point in time, while frequency refers to the number of cycles of the signal that occur in one second. The relationship between amplitude and frequency is inverse, meaning that as the frequency of a signal increases, its amplitude decreases.

2. How can I find a specific amplitude-frequency in the time domain?

To find a specific amplitude-frequency in the time domain, you can use a tool called a spectrum analyzer. This device measures the amplitude and frequency of a signal and displays it on a graph, allowing you to easily identify the desired amplitude-frequency.

3. What factors can affect the accuracy of finding a specific amplitude-frequency in the time domain?

There are several factors that can affect the accuracy of finding a specific amplitude-frequency in the time domain. These include noise interference, signal distortion, and the limitations of the measuring device. It is important to carefully calibrate and troubleshoot these factors in order to obtain accurate results.

4. How can I use the information from finding a specific amplitude-frequency in the time domain?

The information obtained from finding a specific amplitude-frequency in the time domain can be used in a variety of applications, such as audio and video signal processing, wireless communication, and medical imaging. It can also help in analyzing and troubleshooting signal quality issues.

5. What are some common methods for finding a specific amplitude-frequency in the time domain?

Some common methods for finding a specific amplitude-frequency in the time domain include Fourier analysis, which decomposes a signal into its individual frequencies, and autocorrelation, which measures the similarity of a signal to itself at different time intervals. Other methods include wavelet analysis and digital filtering techniques.

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