IIR filter design (butter, cheby1) in SciPy - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to design a Butterworth lowpass filter with cutoff frequency 0.3.

SciPy

from scipy.signal import [1]

b, a = [1](4, 0.3, btype='low')

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Afirwin

Bcheby1

Cbutter

Dlfilter

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cheby1' instead of 'butter' for Butterworth filter design.

Confusing filter design functions with filtering functions like 'lfilter'.

The butter function designs a Butterworth filter. Here, it creates a 4th order lowpass filter with cutoff 0.3.

2fill in blank

medium

Complete the code to design a Chebyshev type I highpass filter with 3 dB ripple and cutoff frequency 0.4.

SciPy

from scipy.signal import cheby1

b, a = cheby1(5, [1], 0.4, btype='high')

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A1

B3

C0.5

D0.1

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing the ripple parameter with cutoff frequency.

Using values less than 1 dB which might be too small for this example.

The second argument to cheby1 is the ripple in the passband in decibels. Here, 3 dB ripple is specified.

3fill in blank

hard

Fix the error in the code to design a Butterworth bandpass filter between 0.2 and 0.5.

SciPy

from scipy.signal import butter

b, a = butter(4, [1], btype='bandpass')

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A[0.2, 0.5]

B0.5

C0.35

D0.2, 0.5

Attempts:

3 left

💡 Hint

Common Mistakes

Passing two separate arguments instead of a list for cutoff frequencies.

Using a single float value for bandpass cutoff.

The cutoff frequencies for a bandpass filter must be given as a list or tuple of two values, e.g., [0.2, 0.5].

4fill in blank

hard

Fill both blanks to create a Chebyshev type I bandstop filter with order 3, ripple 2 dB, and cutoff frequencies 0.3 and 0.6.

SciPy

from scipy.signal import cheby1

b, a = cheby1([1], [2], [0.3, 0.6], btype='bandstop')

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A3

B2

C4

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping order and ripple values.

Using ripple values too large or too small.

The first argument is the filter order (3), and the second is the passband ripple in dB (2) for the Chebyshev type I filter.

5fill in blank

hard

Fill all three blanks to create a Butterworth lowpass filter of order 6 with cutoff 0.25 and design it using 'butter'.

SciPy

from scipy.signal import [1]

b, a = [1]([2], [3], btype='low')

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

Abutter

B6

C0.25

Dcheby1

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing 'butter' and 'cheby1' in the same code.

Using incorrect order or cutoff values.

The butter function is imported and called with order 6 and cutoff 0.25 to design a lowpass Butterworth filter.