Windowing before FFT in SciPy - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Hann window function from scipy.signal.

SciPy

from scipy.signal import [1]

Drag options to blanks, or click blank then click option'

Ahamming

Bblackman

Chann

Dbartlett

Attempts:

3 left

💡 Hint

Common Mistakes

Importing the wrong window function like hamming or blackman.

Misspelling the function name.

The Hann window is imported from scipy.signal as hann.

2fill in blank

medium

Complete the code to create a Hann window of length 256.

SciPy

window = hann([1])

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A128

B1024

C512

D256

Attempts:

3 left

💡 Hint

Common Mistakes

Using a window length different from the signal length.

Confusing window length with FFT length.

The window length should match the signal length, here 256.

3fill in blank

hard

Fix the error in applying the window to the signal array named 'signal'.

SciPy

windowed_signal = signal [1] window

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A+

B*

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Adding or subtracting the window instead of multiplying.

Dividing the signal by the window.

Windowing is done by multiplying the signal by the window element-wise.

4fill in blank

hard

Fill the blank to compute the FFT of the windowed signal and get its magnitude.

SciPy

fft_result = np.fft.[1](windowed_signal)
magnitude = np.abs(fft_result)

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Afft

Bifft

Creal

Dimag

Attempts:

3 left

💡 Hint

Common Mistakes

Using inverse FFT instead of FFT.

Trying to get magnitude by accessing .real or .imag.

Use np.fft.fft to compute the FFT and np.abs to get the magnitude.

5fill in blank

hard

Fill all three blanks to create a windowed signal, compute its FFT, and plot the magnitude spectrum.

SciPy

import matplotlib.pyplot as plt

window = hann([1])
signal = np.sin(2 * np.pi * 5 * np.arange([2]) / [3])
windowed_signal = signal * window
fft_result = np.fft.fft(windowed_signal)
magnitude = np.abs(fft_result)
plt.plot(magnitude)
plt.title('Magnitude Spectrum')
plt.xlabel('Frequency Bin')
plt.ylabel('Magnitude')
plt.show()

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A256

B100

D512

Attempts:

3 left

💡 Hint

Common Mistakes

Using different lengths for window and signal.

Not matching the range length with window length.

The window length and signal length must match (256). The signal is created with 256 points.