RET 2013: INFORMATION IN RADIO WAVES Ken Jacobs Tim Scaduto CORE UNITS Fundamentals of EM spectra with emphasis on radio frequencies History of radio astronomy Information theory and Remote Sensing Information transmitted through radio Natural sources of radio Technology of radio transmission 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' your ideas? information - transfer of ideas, forces, patterns, properties, energy, SENDERS AND RECEIVERS 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 With your teammate: 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. Your job is to guess the sentence exactly by asking 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 ? Why did one have more information than another? 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 here are some practice tasks: • • • easy: pick up an object, rotate, .... medium: clap your hands, touch your nose 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 accuracy of your task? 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. ELECTROMAGNETIC RADIATION (EMR) AS A 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 were made remotely. 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 the incoming radiation. 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 something about the source. http://en.wikipedia.org/wiki/Image:Mimas_moon.jpg ACTIVE VS. PASSIVE REMOTE SENSING Passive sensing detects radiation from natural 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 already know about the message 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.