Waves & Signals

Overview
Welcome to the Waves & Signals area. Here traveler you must counquer the two enemies, Waves & Signals, who protect the entrance to the next area. Move swiftly but carefully as you defeat the two basic monsters of Telecommunications 201.

Types of Waves

 * Transverse
 * Vibrations perpendicular to the direction of the propagation of the wave.
 * Electromagnetic
 * Longitudinal
 * Vibrations parallel to the direction of the propagation of the wave.
 * Sound

Waveshape/Waveform

 * A wave is a displacement in a medium.
 * Shows the shape of a singal as varied with time.
 * Infinite variety of waveshapes that vary with the characteristics of the signal
 * http://electronics.howstuffworks.com/analog-digital2.htm

Signals

 * Time-varying events
 * Convey information
 * Travel over a medium
 * air
 * space
 * wire
 * Plot of signal gives a waveform
 * Can be aperiodic or periodic

Types of Signals

 * Electrical
 * Acoustical
 * Light

Amplitude
Amplitude is the magnitude of change in the oscillating variable. (Interactive Demonstration)


 * Intensity is measured in decibals.
 * The more particles that can be made to vibrate, the louder or more amplified the sound and greater the intensity.

Frequency
Frequency is the rate at which a sine wave repests itself.
 * Measured in Hz (number of cycles per 1 second)
 * The audible frequency range that humans can hear is 20 Hz - 20,000 Hz.
 * Any sound below the range is called infrasound.
 * Any sound above the range is called ultrasound.
 * Example of differenct sounds at different Hz: http://electronics.howstuffworks.com/telephone8.htm

Fourier Theorm
Any periodic waveform can be expressed as the sum of sine waves with frequencies at integer or harmonic multiples of the fundamental frequency of the waveform and with appropriate maximum amplitude and phases.
 * Fourier Analysis / Synthesis

Spectrum
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 * A continuous range of frequencies
 * in a given part of the spectrum waves have common characteristics
 * Spectrum of a signal describes the frequency content of the signal
 * provides an alternative method of viewing the signal
 * often more revealing than the original description of the signal as a function of time

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