Topic 3

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University of Texas, San Antonio *

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2733

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Communications

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Jun 10, 2024

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docx

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Module 3: Topic 3.1 Broadcast Media – Basics Print out this skeletal outline to take notes on key elements discussed in the lecture. Note, please look over the entire slideshow. However, this is to help you with the most important topics to prepare you for the module 1 exam. Course Objectives:  CLO1 – Identify key historical aspects related to communication technologies, including economic, political, societal, and cultural aspects.  CLO2 – Identify modern digital communication trends.  CLO3 – Explain historical and/or modern aspects of communication technologies. Module Overview: In this module, you will learn about the basic principles of broadcast media (e.g., over-the-air radio). You will also learn the history, underlying technical principles, and regulation of broadcast radio. By the end of this module, you will be able to:  LO3.1: Identify the basic principles of airwave broadcasting (supports CLO1)  LO3.2: Identify the basic principles of radio broadcasting (supports CLO1)  LO3.3: Identify the key technologies and people involved with early radio (supports CLO1)  LO3.4: Explain historical and/or modern aspects of broadcasting (supports CLO3) Main Questions to Be Answered by the end of the Module: Make sure you can answer the following questions by the end of this module: 1. What is electromagnetic energy? 2. What are the properties of radio waves? 3. What is Frequency Measurement? 4. What is wave propagation? 5. What is the Radio Frequency Spectrum? 6. What are Radiators? 7. What are the different types of antennas? 8. What are Long vs. Short Wavelengths? _____________________________________________________________________________________ Basic Principles of Electronic Media (see Radio Wave Basics lecture video) Define electromagnetic energy? (Write out the information needed in the space provided below):  Define the electric part: o Electric – Alternative Current/Direct Current  Alternative Current – electrical currents repeatedly and regularly alternating (i.e..: changes)  Direct Current – electrical current flowing continuously in one direction/1D o AC/DC went electrical  Define the magnetic part: COM 2733 - SKELETAL OUTLINE NOTES

o Magnetic portion  AC is used and creates radiation  More alternations = more radiation  This type of radiation is called “Radio Waves”  Radio Waves – the alternating current creates a bit of radiation around the source that radiates through the air  Lamp analogy o The electrons flow straight from the source to the lamp (direct current electricity). Electrons are engaged when you turn the lamp on, but with alternating current, the power goes back and forth on the wire. Those alternations create radiation that radiates away from the source. That principle is what is used for radio waves.  Radio Tower o A metal conductor running electricity on the radio wave tower. If you want to transmit out AM radio to listen to in your car, what is done is the electricity runs up and down the wire. When it's being done, that would create radiation around the tower, and the radiation would gradually go away from the tower, go through the air, and be picked up by your car. This is true for all radio transmissions and happens with cell phone towers sending out information signals if you have internet working on your cellphone. Properties of Radio Waves (see Measurement and Propagation lecture video) List the 2 properties of radio waves. (Write out the information needed in the space provided below):  First property of radio waves o Power – the amount of electrical current put into the radio waves (e.g., a little to a lot or vise versa)  Has bigger waves and more amplitude  The more power you put into it, the further that wave in going to travel.   Second property of radio waves o Frequency – the rate of the alternating current (e.g., slow to fast, or vise versa)  Has faster waves  Power is the amount of electricity put into it. Frequency is the speed of electricity.   Car analogy COM 2733 - SKELETAL OUTLINE NOTES

o The cars on the road and the speed of the cars on the road. Power is the # of electrons that are allowed to flow on the wire. You can have one electron or increase the number of electrons you have, like increasing the # of cars that you have on the roads. More cars + more power. o Frequency is the speed or the rate of the flowing electrons; you can have a few # of the electrons flowing relatively slowly, or you can have a few # of electrons going very fast. You can change the # of electrons in the speed; you can have a few electrons at a low power with a high frequency or a low frequency, or you can increase the # number of electrons drawn to increase the power further. Still having it relatively slow rate or you can have that go at a faster rate. NOTE: power and frequency are independent of each other. Frequency Measurement (see Radio Wave Basics lecture video) Explain Frequency Measurement (Write out the information needed in the space provided below):  Frequency Measurement o A complete cycle  Alternation of a radio wave from momentary 0, through the +, through the -, then back to zero. o Frequencies are measured by Hertz (Hz)  # of complete wave cycles in 1 second  More cycles = more Hertz Wave Propagation (see Radio Wave Basics lecture video) Identify and describe components of the wave propagation. (Write out the information needed in the space provided below):  Recall: radio waves are made of electricity and magnetism  Magnets of like polarity repel each other  The + and – aspects of the wave act like the poles on a magnet(ex. North and North while South and South repel each other, opposites attract.)  As each radio wave is emitted, it repels (or propels) the preceding wave before it o Once the radio tower creates one radio wave and sends it off in the air, it would die away if there were no continuous radio waves being sent out. By having the electrons go up and down on the antenna, you create another radio wave, which then pushes the first one. Then you continue with the electricity that creates another radio wave which then pushes the second one.  Radio wave propagation = radio transmission COM 2733 - SKELETAL OUTLINE NOTES

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