1. Introduction Concepts and Definitions 1 st semester 1436-1437 King Saud University College of Applied studies and Community Service 1301CT By: Nour Alhariqi

2. Waves (Signals) Wave is a disturbance or oscillation that travels through space and matter, – sound waves, voltage waves,.. A waveform is a graphic representation of a wave. ▫ A voltage waveform shows time on the horizontal axis and voltage on the vertical axis time voltage

3. Waves (Signals) Waveform shapes tell you a great deal about a signal. Any time you see a change in the height of the waveform, you know the voltage has changed. Any time there is a flat horizontal line, you know that there is no change for that length of time. Straight diagonal lines mean a linear change - rise or fall of voltage at a steady rate. Sharp angles on a waveform mean sudden change.

4. Waves (Signals) Some common waveforms: ▫ Sine waves and damped sine waves. ▫ Square and rectangular waves. ▫ Triangle and saw-tooth waves. ▫ Step and pulse shape.

5. Sine Waves and Damped Sine Waves The sine wave is a wave that has a smooth repetitive oscillation. The damped sine wave is a special case that oscillates, but winds down over time

6. Square and Rectangular Waves A square wave is a wave that turns on and off (or goes high and low) at regular intervals. The rectangular wave is like the square wave except that the high and low time intervals are not of equal length.

7. Sawtooth and Triangle Waves In sawtooth and triangle waves the transitions between voltage levels change at a constant rate. These transitions are called ramps. a sawtooth wave ramps upward and then sharply drops. A triangle wave has symmetrical rising and falling ramps.

8. Step and pulse shape A step indicates a sudden change in voltage, similar to the voltage change you would see if you turned on a power switc. A pulse indicates sudden changes in voltage, similar to the voltage changes you would see if you turned a power switch on and then off again A collection of pulses travelling together creates a pulse train.

9. Analog and Digital Signals Analog signalDigital signal The analog signal is a signal that takes continuous range of values to represent information (e.g. sine waves). The digital signal is a signal takes discrete values to represent information (e.g. square waves).

10. Periodic and Aperiodic Signal periodic signalaperiodic signal The periodic signal is a signal that repeats itself after a specific interval of time. One completion of the repeating pattern is called a cycle. The aperiodic signal is a signal that does not repeat itself after a specific interval of time.

11. Some Measurements Frequency is a measurement of how many cycles occurs in a one second. Period is the time taken to complete one cycle. The amplitude (peak amplitude, V p ) of a signal is the largest value it takes (is measured from the X- axis, 0 V, to the top of a peak) The peak-to-peak amplitude, V pp, is measured between the maximum positive and negative values