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File:Phase shifter using IQ modulator.gif

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Original file(842 × 380 pixels, file size: 1.57 MB, MIME type: image/gif, looped, 72 frames, 8.6 s)

Summary

Description
English: Phasor and wave diagram animation showing how phase change is achieved in I+Q signal by changing I (inphase cosine component) and Q (quadrature sine component) signals amplitude in IQ modulators. For Python code used to generate this image, go to the image file description page by clicking "More details" button.
Date
Source Own work
Author Vigneshdm1990

Source code Python Matplotlib

The following python code is used to generate 72 images used in this animation. Then using an online gif image maker "ezgif.com" these 72 images are combined to get gif image.

# Python code using matplotlib library to generate 72 images to create a gif file that shows
# how phase change is achieved by changing I and Q signals amplitude in IQ modulators
# 
# I- inphase Q-quadrature

# Physics concept : how by only changing the magnitude of I and Q signals amplitude
# one can change the phase of I+Q wave signal

import matplotlib.pyplot as plt
import numpy as np

# t is the current phase, and phase is changed from 0° to 355° in the steps of 5°

for t in range(0,356,5):

    # I) CREATING FUNCTION FOR PLOTTING

    # creating a blue circle in PHASOR DIAGRAM using parametric equation (radius=1, theta=s)
    s=np.linspace(0, 2 * np.pi, 400)
    x1=np.cos(s)
    y1=np.sin(s)

    # creating I and Q vectors magnitude (x=I, y=Q) in PHASOR DIAGRAM
    x = 1*np.cos(0.0174533*t)
    y = 1*np.sin(0.0174533*t)

    # creating I, Q, I+Q amplitude and Phase (0° to 720°) for WAVE DIAGRAM
    x2 = np.linspace(0, 721, 400) # Pahse from 0° to 720° divided into 400 points
    y2 = 1*np.sin(0.0174533*t)*np.sin(0.0174533*x2) # Q
    z2 = 1*np.cos(0.0174533*t)*np.cos(0.0174533*x2) # I
    q2 = (y2 + z2) # (I+Q)

    # creating text to show current phase t
    text1 = "phase = " + str(t)+'°'

    # II) CREATING THE PLOT (phasor and wave diagram in one plot arranged 1 x 2)

    # ax1 = Phasor diagram subplot and ax2 = Wave diagram subplot
    fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(9.5,4.1))
    ax1.title.set_text('Phasor diagram')
    ax2.title.set_text('Wave diagram')

    # Setting the position of the subplot title
    ax1.title.set_position([.5, 1.05])
    ax2.title.set_position([.5, 1.05])

    # II-A) PHASOR DIAGRAM

    # including the current phase inside the Phasor diagram subplot
    ax1.text(0.9, 0.9, text1, bbox=dict(boxstyle="square",facecolor='white', alpha=0.5))

    # setting the y axis limit
    ax1.set_ylim(-1, 1)

    # Plotting the blue outer circle of radius = 1
    ax1.plot(x1, y1, 'b')

    # Move left y-axis and bottom x-axis to centre, passing through (0,0)
    ax1.spines['left'].set_position('center')
    ax1.spines['bottom'].set_position('center')

    # Eliminate upper and right axes
    ax1.spines['right'].set_color('none')
    ax1.spines['top'].set_color('none')

    # Show ticks in the left and lower axes only
    ax1.xaxis.set_ticks_position('bottom')
    ax1.yaxis.set_ticks_position('left')

    # Setting the y axis ticks at (-1,-0.5,0,0.5,1)
    ax1.set_yticks([-1,-0.5,0,0.5,1])

    # Creating Arrows and dashed lines
    ax1.arrow(0, 0, x, y, length_includes_head='True', head_width=0.05, head_length=0.1, color='g') # I+Q
    ax1.arrow(0, 0, x, 0, length_includes_head='True', head_width=0.05, head_length=0.1, color='b') # I
    ax1.arrow(0, 0, 0, y, length_includes_head='True', head_width=0.05, head_length=0.1, color='r') # Q
    ax1.arrow(x, 0, 0, y, length_includes_head='True', head_width=0, head_length=0, ls='-.') # vertical dashed lines
    ax1.arrow(0, y, x, 0, length_includes_head='True', head_width=0, head_length=0, ls='-.') # Horizontal dashed lines

    # II-B) WAVE DIAGRAM

    # setting the y axis limit
    ax2.set_ylim(-1.5, 1.5)

    # Setting the y axis ticks at (0, 180, 360, 540, 720) degree phase
    ax2.set_xticks([0, 180, 360, 540, 720])

    # Setting the position of the x and y axis
    ax2.spines['left'].set_position(('axes', 0.045))
    ax2.spines['bottom'].set_position(('axes', 0.5))

    # Eliminate upper and right axes
    ax2.spines['right'].set_color('none')
    ax2.spines['top'].set_color('none')

    # Creating x and y axis label
    ax2.set_xlabel('Phase (degree)', labelpad=0)
    ax2.set_ylabel('Amplitude', labelpad=0)

    # Plotting I, Q and I+Q waves
    ax2.plot(x2, z2, 'b', label='I', linewidth=0.5)
    ax2.plot(x2, y2, 'r', label='Q', linewidth=0.5)
    ax2.plot(x2, q2, 'g', label='I+Q')

    # function for amplitude of I+Q green arrow
    c1=1 * np.cos(0.0174533 * t) * np.cos(0.0174533 * t)+1*np.sin(0.0174533*t)*np.sin(0.0174533*t)

    # plotting I+Q arrow that moves along to show the current phase
    ax2.arrow(t, 0, 0, c1, length_includes_head='True', head_width=10, head_length=0.07, color='g')

    # plotting I and Q amplitude arrows at position 180° and 90° respectively
    ax2.arrow(180, 0, 0, 1*np.cos(0.0174533*t)*np.cos(0.0174533*180), length_includes_head='True', head_width=10, head_length=0.07, color='b')
    ax2.arrow(90, 0, 0, 1*np.sin(0.0174533*t)*np.sin(0.0174533*90), length_includes_head='True', head_width=10, head_length=0.07, color='r')

    # Creating legend
    ax2.legend(loc='center', ncol=3, bbox_to_anchor=[0.5, 0.94])

    # Adjusting the relative position of the subplots inside the figure
    fig.subplots_adjust(left=0.07, bottom=0.15, right=None, top=None, wspace=0.3, hspace=None)

    # Saving the figure
    fig.savefig('0file%s.png' %t)

    # Clearing the figure for the next iteration
    fig.clf()

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
w:en:Creative Commons

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Captions

Animation of a phase shifter using IQ modulator. By changing the amplitude of I and Q waves one can change the phase of the I+Q wave.

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2 February 2020

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Date/TimeThumbnailDimensionsUserComment
current21:26, 2 February 2020Thumbnail for version as of 21:26, 2 February 2020842 × 380 (1.57 MB)Vigneshdm1990User created page with UploadWizard
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