Download Analog Signals

Electromagnetic Waves in
Communication
NGSS Performance Expectation
MS-P4-3
• Integrate qualitative scientific and
technical information to support the
claim that digitalized signals are a more
reliable way to encode and transmit
information than analog signals.
Emphasis is on waves used for
communication, including the
conversation of binary patterns.
• Waves carry energy, but did you know
that WAVES ALSO CARRY
MESSAGES
• If my voice (sound ) travels in a
Mechanical wave than how does my
best friend hear my voice on my cell
phone if my cell phone has
electromagnetic waves? How does my
favorite music artists’ voice play back
once downloaded? Hmmmm……
Brain Pop Analog and digital
Recording
• A lot of our personal world is
transmitted digitally in our cellphones:
texts, selfies, and emails, but are all
waves digital?
• Lets see what Tim and Moby have to
say about this
• https://www.brainpop.com/technolog
y/scienceandindustry/analoganddigita
lrecording/
So what is Analog
• In communication, signals are
generated from a transmitter which are
sent to receivers to create messages.
• One type of Analog
technology is a clock
Analog
• An analog watch tells the time with hands
that sweep around a dial: the position of the
hands is a measurement of time. It’s
ANALOGOUS of the passing
of time. Its not the actual
passing of time, but it
illustrates the passing of time.
The ticking of the clock is
constantly moving.
Analog
Before computers, everything was Analog
Examples are an old style camera or an
old cassette recording. Images captured
on chemically treated paper were
analogous of the true image and
recordings of voice were captured on
magnetized tape which was analogous of
the true voice. Images and sound were
clear.
Other Areas of Anaolg Technology
• Old telephone networks
• Most television broadcasting at present
• Radio broadcasting
Analog Signals: The Basics
Signal
Amplitude
Frequency =
Cycle/Second
A typical
sine wave
Time
Cycle
Amplitude and Cylce
• Amplitude
– Distance above reference line
• Cycle
– One complete wave
– Amplitude is what give is AM Radio
stations
Frequency
• Frequency
– Cycles per second
– Hertz is the unit used for expressing
frequency
• Frequency spectrum
– Defines the bandwidth for different analog
communication technologies
– Frequency has to do with FM Radio
stations
Information Representation
Using Analog Signals
• Analog information is translated into
electric pulses of varying amplitude
– Analog signal is continuous
– Denoted by Sine Wave
– Analog technology records waveforms as
they actually are
–
Digital
• Digital is entirely different.
• In digital technology, translation of
information is into binary format (zero
and one) where each bit is represented
of two distinct amplitudes.
– A bit is a one or a zero
– A byte is a string of 8 ones and zeros.
Digital Signal
1 0 1 1 0 1 0 0
Pulse
Pulse Duration
Time
• A digital signal uses decrete
(discontinuous) values
• Digital is measured with Sampling
• Lets watch this video
• https://www.youtube.com/watch?v=b
tgAUdbj85E&spfreload=1
Digital Advantage
 Easier
to store information and takes up less
space. Ex. MP3 or Kindle
 More secure:cellphone
 Editing
 Processing using computer technology
 Programmable services
 Better quality due to being able to reconstruct
exact digital patterns at the receiving end
 Faster communication speeds are possible
Digital Disadvantages
• Analog is more accurate
• Analog last longer
– No one has the first email or cell phone
conversation
Sampling does not precisely capture the
original wave when converted so it is not as
accurate.
Analog Digital Conversion
1 0 1 1 0 1 0 0
A to D Converters, Digital
Signal Processors (DSP) etc.
• So is Digital better than Analog? You be
the judge