EE 1105 Pre-­‐Lab 7 Sine, Square and Triangular Waveforms
INTRODUCTION In electrical engineering, we deal with different types of signals that are frequently used
as inputs to electric systems, e.g., to an electric circuit. The most common signals are the
triangular, square and sinusoidal waveforms. A waveform means the shape and form of a
signal such as a wave moving in a physical medium or an abstract representation. These
waveforms have some parameters that are of special interest in signal analysis: the period
of a function whose units are seconds (s) and the frequency, the inverse of the period, and
whose unites are hertz (Hz). There are two instruments, that we will learn how to use,
that handle waveforms. The function generator provides us different signals such as
triangle, square and sine. We also can set some waveform parameters as period and
amplitude. The second instrument is the oscilloscope, which can be used to pictorially
represent a wave as a repeating image on a screen.
Sinusoidal Signals The following graph defines several properties of sinusoidal signals that are important to electrical engineers. Most of these should be familiar. However, the concept of phase shift may not be. This latter concept is useful since many signals seen in communications exhibit shifts in time from transmission point to receiver. 1
Period =
frequency
Phase shift
Amplitude
Peak-to-Peak
Amplitude
Time
Fig 1. Sinusoidal signal with time (x-­‐axis) and amplitude/magnitude (y-­‐axis) EE 1105
Square Signals Square signals are very frequently found in digital circuits and are naturally generated by binary logic devices. We can use them as timing references, because of their fast transitions from one value to another; they are suitable for triggering logic circuits at accurately determined intervals.
1
Period =
frequency
Amplitude
Peak-to-Peak
Amplitude
Time
Fig 2. Square signal with time (x-­‐axis) and amplitude/magnitude (y-­‐axis) Triangular Signals A triangle wave is a very basic waveform where the pattern rises and then falls by the same gradient creating a triangle shape. 1
Period
=
frequency
Amplitude
Peak-to-Peak
Amplitude
Time
Fig 3. Triangular signal with time (x-­‐axis) and amplitude/magnitude (y-­‐axis) 2
EE 1105
PRELAB 1. Find the period, frequency, amplitude and peak to peak amplitude for the next signals: a) Sinusoidal b) Square 3
EE 1105
c) Triangular 2. Sketch the plots for: i) sinusoidal wave with a period of 3π/2 seconds and an amplitude of 4 ii) square wave with a frequency of 0.2 Hz and a peak to peak amplitude of 10 iii) triangular wave with a period of 3 seconds and a peak to peak amplitude of 4. 4