1. Cell Phones CSCI 107 Spring 2010

2. Origin The concept of the cellular phone was developed by Bell Laboratories in 1947. Originated from the mobile car phone. The first actual cell phone was made in 1973 by Martin Cooper of Motorola. Cell phones were first made available to the public in 1984. The first cell phone weighed 2 pounds and cost $1000. Taken from http://library.thinkquest.org/04oct/02001/home.htm

3. Why cell phones? Each region is divided into cells of approx. 10 square miles. Each cell has a hexagonal shape with a tower in the center. A cell phone carrier a fixed number of radio channels to use per region. Each cell uses 1/7 of the available channels The same channels can be reused in non- adjacent cells. Taken from http://electronics.howstuffworks.com/cell-phone.htm

4. Cell phone Channels A pair of frequencies (1 for transmit and 1 for receive) is used to create 1 channel. The frequency bands used in analog voice channels are typically 30 kHz wide. The complete picture

5. Channels In 1G times, each cell had about 56 voice channels. –carrier got 832 radio frequencies in a city –cell phone uses two frequencies per call --- 395 voice channels per carrier. –The other 42 frequencies used for control channels The power consumption of the cell phone was low –transmission did not need to travel far –required a large number of base stations 1 central office called the Mobile Telephone Switching Office (MTSO) per city –handles all of the phone connections to land-based phone system –controls all of the base stations in the region

6. How it all works http://electronics.howstuffworks.com/cell- phone3.htmhttp://electronics.howstuffworks.com/cell- phone3.htm

7. Safety Cellular phones give off an electromagnetic energy The electromagnetic energy that cellular phones create can penetrate through your body. The depth of penetration and absorbtion come from how close the phone is held and how strong its signal is. It is possible that cell phones cause serious health issues such as epileptic seizures or changes in brain activity, and reaction time, but nothing has been definitely proven. They may interfere with medical devices and aircraft electronics. Taken from http://library.thinkquest.org/04oct/02001/safety.htm

8. Cultural Aspects How you use your mobile phone has long reflected where you live. Taken from http://www.economist.com/sciencetechnology/displaystory.cfm?story_id=15172850

9. Pervasive Use In rich countries subscriptions outnumber the population. In poor countries more than half the inhabitants have gone mobile.

10. All alike, all different In 2002 the average Japanese mobile user spoke for 181 minutes each month. By 2009 that had fallen to 133 minutes. –Tokyo’s teenagers have been called the “thumb generation”. On average Germans spend only 89 minutes each month calling others. Americans average monthly talk-time is a whopping 788 minutes. Puerto Ricans have the highest monthly average in the world of 1,875 minutes.

11. All alike, all different In Italy and Greece people are worried about the supposed health risks of electromagnetic fields. A 2007 survey found that 86% of Greeks and 69% of Italians were “very” or “fairly” concerned about these health risks. This compares with 51% in Britain, 35% in Germany and only 27% in Sweden.