ENVS 1200 Chapter Notes - Chapter 1: Wireless, Sine Wave, Analog Transmission
13 May 2018
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ENVS 1200 Chapter 1 Notes – Summary
Introduction
Analog Signaling
• The medium itself may require transformation of a signal from analog to digital (A-to-D)
or vice versa if the signal is to be transmitted through a medium that can carry only one
or the other.
• Wires can carry either digital or analog signals, but as we already noted, normal
residential phone lines carry analog signals.
• Radio signals, known as radio waves, require another type of analog signal, with the
digital signal embedded within.
• Although digital transmission is favored for most use these days, analog transmission
methods are required for wireless media
• Such as radio and sound, for wireless networking, and for other forms of wireless data
communication
• Radio transmission methods include satellite, cellular phone, wireless networking, and
microwave communications.
• Radio waves can also be converted to equivalent electrical signals and used with wire
media and may be preferred when a mixture of digital and analog data is being
transmitted through the cable
• Such as cable TV with a digital Internet feed, though most cable TV is now digitally
distriuted ad overted, if eessary, to aalog at the ustoer’s site.
• The basic unit of analog transmission is a sine wave. A sine wave is shown
• A sine wave has peak amplitude A, or size, and a frequency, measured as the number of
times the sine wave is repeated per second.
• The instantaneous value of the sine wave varies with time, ranging from 0 to amplitude
A, ak to 0, to value −A, ad ak to 0 agai.
• The value may measure voltage, or loudness, or the mechanical movement of the metal
in a bell, or the movement of air in an organ pipe, or some other quantity.
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