This document discusses the electromagnetic spectrum and how electromagnetic energy works. It explains that electromagnetic energy comes in many forms, including visible light, radio waves, x-rays, and more. These forms of energy can travel through space as electrical and magnetic waves. The document also covers topics like frequency, wavelength, modulation, sidebands, bandwidth, multiplexing, and compression as they relate to electromagnetic signals and the transmission of information through various parts of the electromagnetic spectrum.

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 transmitter’s 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” wave relative 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