Fourier Transform Graph Calculator

Enter signal settings and graph spectra instantly. View magnitude, phase, power, and bins clearly together. Download results for lessons, reports, and signal checks today.

Calculator

Example Data Table

Signal Amplitude Frequency Sample Rate Duration Expected Strong Bin
Sine 1 5 Hz 128 Hz 1 s 5 Hz
Square 1 8 Hz 256 Hz 1 s 8 Hz and odd harmonics
Custom Sample based From data 100 Hz Sample count divided by rate Depends on samples

Formula Used

The calculator uses the discrete Fourier transform for sampled data.

X[k] = Σ x[n] w[n] e-j2πkn/M

Here, x[n] is the sample, w[n] is the window value, M is the transform length, and k is the bin number.

Frequency bin = k × sample rate / M

Magnitude = √(real² + imaginary²)

Phase = atan2(imaginary, real)

Power = magnitude²

How To Use This Calculator

Choose a signal type or paste custom sample values.

Enter amplitude, frequency, phase, offset, sample rate, and duration.

Select DFT points, window type, and normalization style.

Press the calculate button to show the result above the form.

Review the time graph, magnitude graph, phase graph, and bin table.

Use the CSV or PDF buttons to save the calculated data.

Understanding Fourier Transform Graphs

A Fourier transform graph changes a time signal into a frequency view. This view shows which waves build the signal. It is useful in maths, audio, vibration, electronics, and data science. A plain waveform can look crowded. A spectrum separates the same data into clear frequency bins.

Time Domain And Frequency Domain

The time graph shows sample value against time. It helps you see peaks, cycles, offsets, and sudden changes. The frequency graph shows magnitude against frequency. Large bars mark strong repeating parts. Phase shows where each wave starts. Power shows the energy share of each bin.

Why Windowing Helps

Real samples are finite. A short record can end between two cycles. That mismatch spreads energy across nearby bins. This effect is called leakage. A window tapers the edges before the transform. Hann, Hamming, and Blackman windows reduce leakage. Rectangular keeps raw data unchanged.

Sampling And Resolution

Sample rate controls the highest useful frequency. The limit is half the sample rate. Duration controls frequency spacing. A longer record gives closer bins. More transform points can add smooth zero padded bins. It does not create new information. It only makes the plotted curve easier to inspect.

Using This Calculator

Choose a standard signal or paste custom samples. Set amplitude, frequency, phase, offset, and harmonics. Select sample rate and duration. Pick a window and normalization style. Then calculate the graph. Review the strongest bins first. Compare them with the expected signal frequency.

Reading Results Carefully

Magnitude values depend on scaling. Single sided scaling is often best for real signals. Phase can jump near weak bins, because tiny magnitudes have unstable angles. Noise, short records, and wrong sample rates can hide details. Use clean inputs when learning. Use longer durations when close frequencies must be separated.

Practical Uses

Students can test sine, square, triangle, and saw waves. Teachers can demonstrate harmonics. Engineers can inspect vibration tones. Audio users can find dominant pitch areas. Analysts can export samples for reports. The graph gives a fast bridge between formulas and real signals.

It also supports quick checks during homework and lab work. Repeating the same signal with different options shows how each setting changes the final spectrum clearly in useful ways.

FAQs

What does this calculator graph?

It graphs the time signal, magnitude spectrum, and phase spectrum. It also lists frequency bins with magnitude, phase, power, real part, and imaginary part.

Can I enter my own samples?

Yes. Select custom samples and paste numbers separated by commas, spaces, semicolons, or new lines. The calculator uses up to 512 samples.

What is the best window option?

Hann is a good general choice. Hamming is also smooth. Blackman reduces leakage more. Rectangular keeps the original data but may show stronger leakage.

What does DFT points mean?

It is the transform length. More points can create a smoother plotted spectrum. It does not add new signal information by itself.

Why is my dominant frequency not exact?

The frequency may fall between bins. Short duration, low sample rate, leakage, or window choice can shift the strongest displayed bin.

What is single sided amplitude?

It scales real signal magnitudes for the positive frequency spectrum. It is useful when you want amplitudes to match common sine wave expectations.

Can I export the graph results?

Yes. The CSV export includes all samples and frequency bins. The PDF export includes the main result and strongest bins.

Is this calculator suitable for lessons?

Yes. It is useful for classroom demos, homework checks, lab reports, and quick signal experiments with common waveforms.


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