Learn Basic Signal Processing using Python

 

To plot both sine and cosine waves,

you can define and plot both functions together

Code that plots the sine and cosine waves on the same graph.

If you're using VS Code and not seeing the plot, there are a few things 

you can check to make sure the plot is displayed properly:

1. Install Necessary Libraries

Ensure that you have both numpy and matplotlib installed. If not, you can install them using the following commands in your terminal.

pip install numpy matplotlib

2. Check VS Code Python Interactive Mode

Ensure you are running your code in a Python Interactive window. 

In VS Code, you can run your script in the Python Interactive window by 

right-clicking your script and selecting "Run Python File in Terminal" or 

by running individual cells if you are using a .ipynb (Jupyter Notebook) file.

3. Check Output in Terminal

If you are running the script in the VS Code terminal, 

try explicitly calling plt.show() at the end of your script to ensure the plot is rendered:

Simple Python code:

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# to plot sine and cos wave

#import libraries

import numpy as np

import matplotlib.pyplot as plt

# to define independent and dependent variable

t = np.arange(0,1, 0.01)

xt= np.sin(2*np.pi*3*t)

#to plot the signal

plt.plot(t,xt) #till here write and run and the output terminal

plt.show() #write this to show the plot

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Code with Legend: 

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import numpy as np

import matplotlib.pyplot as plt

# define independent variable (time)

t = np.arange(0, 1, 0.01)

# define dependent variables (sine and cosine waves)

sine_wave = np.sin(2 * np.pi * 3 * t)

cosine_wave = np.cos(2 * np.pi * 3 * t)

# plot the signals

plt.plot(t, sine_wave, label='Sine Wave')

plt.plot(t, cosine_wave, label='Cosine Wave')

# add labels and title

plt.xlabel('Time (s)')

plt.ylabel('Amplitude')

plt.title('Sine and Cosine Waves')

# add a legend

plt.legend()

# display the plot

plt.show()  # ensure this is included to display the plot in VS Code

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Output:

Explanation:

The expression sin(2 * np.pi * 3 * t) represents a

sine wave with the following characteristics: Amplitude: The sine function typically has an

amplitude of 1 unless it's scaled by a factor. Frequency: The term 3 indicates that the sine wave

completes 3 full cycles per second.

This is the frequency in Hertz (Hz). Angular frequency: The factor 2 * np.pi * 3 is the

angular frequency in radians per second.

In general, angular frequency is related to

frequency 𝑓 by ω=2πf. Time variable: The variable t is typically time and determines

the phase of the sine wave at any given moment.

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#To plot sampled sine (and cosine signal)

import numpy as np

import matplotlib.pyplot as plt

n= np.arange(0,1,0.01)

xn= np.sin(2*np.pi*3*n)

#xn1= np.cos(2*np.pi*3*n)

#plot the signal

plt.stem(n,xn, label= "sine wave")

#plt.stem(n,xn1, label= "cosine wave")

plt.title("hello pradeep bhai, its sine # (and cosine sampled )signal")

plt.xlabel("---> n ")

plt.ylabel("Amplitude in volts")

plt.legend()

plt.show()

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note : 1.Select Sample spacing 0.01 wisely for display in line 3

so select resolution accordingly.

2. stem used for discrete time sequence in place

of plot for continuous time signal.

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