1. EMC 2410Intro to Electronic MediaEdward BowenLecture FourNutshell

2. How does all this work?
3. The Electromagnetic Spectrum
Alphas 2011
4. Electromagnetic Energy
a form of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space
There are many forms of electromagnetic energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.
5. Electromagnetic Spectrum
http://videos.howstuffworks.com/discovery/29406-assignment-discovery-electromagnetic-waves-and-light-video.htm
6. Electromagnetic Spectrum
http://youtu.be/uh3hH_Vu2tU
7. Electromagnetic Spectrum
http://youtu.be/cfXzwh3KadE
8. Electromagnetic Spectrum
9. Electromagnetic Spectrum
10. Burning Sea Water with Radio Waves
http://www.youtube.com/watch?v=e8utkoK2DhA
http://www.cbsnews.com/video/watch/?id=5394576n
http://www.popularmechanics.com/science/4271398
http://www.kanziuscancerresearch.com/
11. Electromagnetic Spectrum
http://www.youtube.com/watch?v=kfS5Qn0wn2o
12. Electromagnetic EnergyShared Properties
They radiate outward from a source without benefit of any discernible physical vehicle
They travel at the same high velocity
They have the properties of waves
Frequency (Time)
Wavelength (Space)
13. The Air Around Us
http://vimeo.com/12621610
14. Wave Frequency
Electromagnetic energy comes from an oscillating (vibrating or alternating) source.
Frequency = number of separate waves produced each second.
Frequency is measured in Hertz (Hz), which is the same as "oscillations per second" or "cycles per second."
15. Wave FrequencyA measure of time
16. WavelengthA measure of space
Distance from the origin of wave to the origin of the next.
17. Radio Waves vs. Audio Waves
Propagate electromagnetically, and can travel through a vacuum as well as many solid materials
Propagate mechanically and require a medium, such as air or water
18. Modulation
Ways of imposing meaningful variations on a transmitters carrier wave to enable it to carry information.
19. Modulation
http://www.youtube.com/watch?v=en2AeCKvlN0
20. Amplitude Modulation (AM)
Manipulating the strength or intensity (amplitude) of the transmitted signal in relation to the information being sent
http://www.youtube.com/watch?v=3ZMPcPR7W3Q
21. Frequency Modulation (FM)
Manipulating the frequency of the carrier waverelative to the information to be transmitted.
http://www.youtube.com/watch?v=ens-sChK1F0
22. Sidebands:
Bandwidth
Multiplexing and Compression
Other Terms
23. Sidebands
When you quote a frequency for a radio station, you generally quote the frequency of the carrier. But when you superimpose a signal on the carrier by AM or FM, the added modulation produces sidebands.
24. Sidebands
The spectrogram of an AM broadcast shows its two sidebands (green) separated by the carrier signal (red)
25. Bandwidth
Signal is to available bandwidth as water is to the size of a pipe. As bandwidth increases, so does the amount of signal that can flow through in a given amount of time, just like as the size of the pipe increases, so does the amount of water that can flow through during a period of time.
Bandwidths are assigned for all types of broadcast communication and this imposes a maximum signal frequency which may be transmitted. The bandwidths assigned to AM and FM radio are such as to limit the fidelity of music broadcasts in AM, but permit the luxury of stereo high-fidelity broadcasts by FM. The high signal frequencies associated with video broadcasting require higher bandwidths for channels assigned to television.
26. Multiplexing / Compression
Multiplexing makes it possible to transfer several video and audio channels simultaneously over the same frequency channel, together with various services.
Compression seeks to eliminate unneeded information through such techniques as dynamic range compression and reducing the quantity of data used to represent digital video images.So what is needed and unneeded?
27. Sidebands - Area of modulated signal to the side of the carrier signal and containing information.
Bandwidth - Amount of signal area allowed or available for a particular use
Multiplexing - Piggybacking lots of different types of info on a signal
Compression - Removing supposedly unneeded information from a signal
Summary