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Chapter 3

The elementary signals

Four lessons in Part I, Signals. Read them in order, or start anywhere: a prerequisite is a link, never a gate.

Start with 3.1
0 of 4 read4 on the essential pathabout 78 minutes

Lessons in this chapter

Spike, for n from -3 to 5.Spike, for n from -3 to 5.

Lesson 1 Essential18 minYou are hereRead

Impulse, step and ramp

Give the spike and the switch from 2.3 their real names, and meet their continuous-time twins.

A cosine wave of height 1.00, repeating every 1.00 seconds.A cosine wave of height 1.00, repeating every 1.00 seconds.

Lesson 2 Essential20 minYou are hereRead

Sinusoids

Name the smooth repeating wave from Chapter 2, read off its amplitude, frequency and phase, and meet its sampled, discrete-time twist.

A plane with axes labelled real and imaginary. A point sits at 3.00 across and 4.00 up, written 3.00 + 4.00j.A plane with axes labelled real and imaginary. A point sits at 3.00 across and 4.00 up, written 3.00 + 4.00j.

Lesson 3 Essential20 minYou are hereRead

Complex numbers for signals

Build complex numbers from nothing, as points and arrows in a plane, so 3.4 can describe a sinusoid as a spinning arrow.

A point on the unit circle at angle 60.0°, at 0.50 + 0.87j.A point on the unit circle at angle 60.0°, at 0.50 + 0.87j.

Lesson 4 Essential20 minYou are hereRead

Complex exponentials & phasors

Set 3.3's fixed point spinning to meet Euler's formula, phasors, beats and decaying spirals.

After this chapter

Where to go next.

The chapters either side, and the rest of Part I in the library.

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