1. Signals Introduction Part 1

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• Signals Basics

• Signal

• Information

• Created when a value changes with time

• Created when a signal changes in an unpredictable way

• Side Notes

• An electrical/electronic circuit is some sort of signal processor

• Any value that changes as a function of time

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• A switch can create a signal

• The Unit Step can represent this simple signal

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• There's an infinite number of signals

• Some aspects of signals - can be used to classify them

• Amplitude

• Mean value (might be zero)

• Root mean square value (will not be zero)

• Number of zero crossings per unit time

• Related to frequency

• Important

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• Electronic devices take an input signal and change it in some way

• Examples:AmplificationRectificationFiltering

• Fundamental Signal Classifications

• Continuous Signal

• Has a value at every point in time

• Discrete Time Signal

• Has a value at distinct points in time

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• T is the time between the signal values (not the time period) in this case

• Signals can be created by summing other signals

• Simple signals, such as sine waves, are added to create more complicated wave-forms - information signals (maybe)

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• Adding continuous signals

• Adding discrete time signals

• Periodic

• Random

• Non-periodic, Not Random

• Values are repeated at regular intervals (periods)

• Random value (can't be determined) at any point in time

• Values are not repeated periodically and are not random

• T = Period

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• Continuous Signals

• Random Signal

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• Discrete Random Signals

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• Non-Periodic, Not Random Signal

• Odd

• Even

• x(t) = x(-t)

• x(t) = -x(-t)

• Symmetric

• Anti-symmetric

• (Cosine Wave)

• (Sine Wave)

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• Signal Symmetry

• Product Rule

• ODD . ODD = EVENEVEN . EVEN = EVENEVEN . ODD = ODDODD . EVEN = ODD

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