# RET 2013: INFORMATION IN RADIO WAVES Ken Jacobs

```RET 2013:
INFORMATION IN
Ken Jacobs
CORE UNITS

Fundamentals of EM spectra with emphasis on radio frequencies


Information theory and Remote Sensing



INFORMATION
THEORY
The foundation of
telecommunications
LEARNING OBJECTIVES
At the end of this unit students will be able to:
 Communicate technical information about how some technological
devices use the principles of wave behavior and wave interactions with
matter to transmit and capture information and energy.
Summative assessment:
Students will look at a case study of radio astronomy and provide a
technical report on the strategies for investigating the radio emissions of
Jupiter.
WHICH OF THESE IMAGES
CONTAINS INFORMATION
WHAT DO WE MEAN BY THE
TERM 'INFORMATION'
information - transfer of ideas,
forces, patterns, properties,
energy,
Claude Shannon
(1906-2001)
inventor of information theory and
modern telecommunication
INFORMATION CONCEPTS
(LEARNING OBJECTIVES)
•
•
The amount of information in every symbol of a message can be
quantified as the entropy of the message.
The transmission channel has rules dependent on the physical
properties of the signal, source, and medium.
CODING WARM UP
o
Have one person think of number between 0-100
o
record the number of yes/no questions required to guess the number
o
repeat for a number between
o
•
0-1000
•
0-1,000,000
•
any whole number
guess a sequence of numbers in a pattern
NUMBER OF GUESSES PER TEAM
Team
1
2
3
1-100
1-1000
11,000,000
sequence
sentence
GAME 1: MEASURING
INFORMATION CONTENT
Guess a sentence
rules:
•
•
•
Your group will be given a sentence of four to six
words with each of the letters (including spaces)
as unknowns.
yes/no questions only.
examples
o
'is this letter a b?'
o
'does it come before m in the alphabet?'
SCORING/REFLECTION
You were each given a different sentence
did they each contain the same amount of information ?
GAME 2: VINCENT-PHIL-SHEP
GAME 2: VINCENT-PHIL-SHEP
Rules:
The game is played with a two player team
•
•
•
o
one player is the robot and the other the navigator
Each team must devise a way for the navigator to
manipulate the robot accomplishing a simple (or not so
simple) task using just three words,
Vincent, Phil, Shep
You have approx. 30 minutes to devise your strategy
o
•
•
•
easy: pick up an object, rotate, ....
hard: find a bottle, do a forward role
GAME 2: REFLECTION
Make an analogy to information transmission

What is the transfer channel?

What is the information?

What are the rules of the transfer channel and how did it affect the time and
Describe your coding strategy, strengths? Weaknesses?
GAME 3: TEXT MESSAGING GAME
Rules
•
•
•
•
•
One student is given a copy of text
That student must re-write the text using only uppercase
letters or numbers and spaces
The goal is to use as few symbols as possible
Once completed the other partner must reconstruct the
message losing 20 pts for each incorrect word.
the score is 1 pt for every character that was saved.
GAME 4: THE KNOCKING GAME

You are given a sentence by your instructor and the only way to
transmit the information to your partner is by knocking on the door.

You have approximately 20 minutes to devise a scheme for your
transmission
TAKE HOME MESSAGE

Information is dependent on what you already know

Moving information requires a transmission channel that has rules

Rules of the transmission channel requires encoding the message
somehow.
TRANSMISSION CHANNEL HAS “RULES”


You can only modify 4
things to send a message

Amplitude

Frequency

Phase

Polarization
These rules correspond to
the limited words available
in the games transmission
channel
CONTRIBUTIONS OF INFORMATION
THEORY
Natural
Science
?
Information
Theory
Computer
Science
Electrical
engineering
ASTRONOMY AS A FIRST SCIENCE

Astronomers were some of the
first scientists who recorded data
over time and made models that
predicted the motion of the
objects they saw

In order to ‘prove’ their theories
they had to use observations that

There was no way to directly
observe the materials of the moon
or mars … YET!
DIRECT OBSERVATIONS APPLIED TO
REMOTE OBSERVATIONS

As the nature of the physical world was researched and developed,
new findings would allow us to conduct different experiments with
the light gathered from night sky objects.

Examples:

Knowledge about optics and the reflection/refraction of light allowed for the first
telescopes

Knowledge about the nature of light as a continuous spectrum allowed us to view
objects and derive their temperature.

Knowledge of the quantum mechanical structure allowed astronomers to develop
and understanding of the composition of materials I both luminous and nonluminous
ENGINEERED TRANSMISSIONS
REMOTE SENSING
PRIMER

Your eyes are the original remote
sensing detector!


We collect visible band EMR
Just like our eye, manufactured sensors
must all be build to detect changes in

Most often we want to create maps or
images of the variations in order to look at
light and dark patterns which could tell us
http://en.wikipedia.org/wiki/Image:Mimas_moon.jpg
ACTIVE VS. PASSIVE REMOTE
SENSING

Passive sensing detects
sources.


Either directly from source or
reflected/refracted by objects
or other medium
Active sensing requires a
source with known
properties be generated
and the effects of
interactions with a target
are observed at the
detector.
CASE STUDY: FINDING COLD
HYDROGEN IN SPACE
CONCLUSION

Information can be quantified and the amount depends on what you

Information carried in radio waves as a transmission channel can be
modified in 4 ways: Amplitude, Frequency, Phase, and, Polarization.

In formation in radio waves from natural sources can help us
understand the properties of the source, the objects they interact
with, and the medium through which they are travelling.

The technique of collecting information form distant objects is called
remote sensing

May be active, we send a signal and measure the results of interactions with target

Passive, look and the signals contained in natural sources and infer properties of
the source, interacting objects, or the medium.
FOR FURTHER STUDY

Refer to the RET 2013 Unit: Natural Sources of Radio to discover
how radio science has increased our understanding of how the
universe works.
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