# Introduction to Convolution Operation

Neso Academy2017-09-12

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💫 Short Summary

The video explores the concept of convolution in LTI systems, detailing the steps involved in calculating outputs using integration and waveform manipulation. It emphasizes the importance of understanding time intervals, signal overlap, and waveform visualization for accurate results. Different cases of signal interaction, including non-zero outputs and varying waveform shapes, are discussed. The video also demonstrates the impact of T values on output waveforms, highlighting the differences between rectangular and triangular pulse convolutions. The use of Laplace transform for similar results is mentioned, providing a comprehensive overview of convolution properties through animation demonstrations.

✨ Highlights

📊 Transcript

✦

The lecture explores the concept of convolution as a crucial mathematical tool for calculating the output of an LTI system.

01:03Convolution involves defining the process, using mathematical formulas, and solving problems related to LTI systems.

Understanding integration is essential for grasping convolution, as the two concepts are closely related.

Key aspects of convolution include the integral, the amount of overlap between functions, and shifting one function over another.

The process of convolution is centered around two functions and how they interact with each other.

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Explanation of convolution formula in LTI systems.

03:29Convolution involves integrating the product of input and impulse response over a range.

Steps for calculating output include using a dummy variable tau and time-shifting operations.

Importance of handling negative signs to avoid confusion in calculations.

Shifting signal waveforms is crucial for accurate results in convolution.

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The convolution operation involves five key steps for calculating the output of an LTI system.

08:48The steps include replacing T by tau, time reversal, time shifting against tau, multiplying X tau and HT, and performing integration.

The example provided showcases the graphical convolution of input XT and impulse response HT to calculate the output YT.

The process involves replacing T by tau in both waveforms, time reversal to obtain the mirror image, and time shifting to plot H t minus tau waveform.

Understanding these steps is essential for mastering the convolution operation.

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The importance of time scaling, time reversal, and time shifting operations in waveforms.

11:28Identifying time instants when signal values change is crucial for effective convolution calculations.

Signals are integrated by shifting them from infinity towards the right and considering different values of T.

Steps four and five are repeated multiple times to calculate integrations through multiplication.

Correctly identifying time instants during waveform shifting is essential for accurate integration calculations.

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Analysis of Multiplication between X tau and HT minus tau.

16:19When T is less than 0, the multiplication and integration result in zero output.

When T is between 0 and 1, there is overlap between the signals, leading to non-zero values.

Multiplication is only non-zero between 0 and T, resulting in a non-zero output.

Integrating from 0 to T yields the same result as integrating from minus infinity to infinity, saving time without affecting the outcome.

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Signal overlap, integration, and waveform visualization based on varying time intervals.

19:56Case 3 and Case 4 show non-zero signal values and overlapping intervals, leading to specific integrations and output values.

In Case 5, when the time interval exceeds 3, there is no signal overlap, resulting in an output value of 0.

The segment highlights the importance of changing time intervals in impacting signal interactions and output results.

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Explanation of output waveform variations based on the value of T.

22:00The output waveform changes depending on whether T is less than 0, between 0 and 1, equal to 1, between 1 and 2, between 2 and 3, or greater than 3.

Two rectangular pulses with unequal widths create a trapezoidal waveform, while equal width pulses result in a triangular waveform when convoluted.

Understanding these properties is crucial for waveform analysis.

Guidance is provided on plotting the obtained waveform in terms of ramp signals.

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Plotting the waveform based on different values of T.

26:21Y(T) expression in terms of ramp signals impacts waveform shape.

Analysis results in representation of output waveform using ramp signals.

Laplace transform mentioned for obtaining similar results in the future.

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Introduction to properties of convolution through an animation demonstration.

29:27Showcases two windows with stationary and moving signals to illustrate overlap and integral calculations.

Convolution value increases linearly as moving signal overlaps more with the stationary signal.

Value stabilizes and eventually decreases as signals move further apart.

Animation provides visual clarity on how convolution works, encouraging viewers to ask questions for clarification.

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