Wally is a slacker, he is always looking for the easy way out of doing anything

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Wally is a slacker, he is always looking for the
easy way out of doing anything
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The 100 computer?
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AC vs DC Circuits
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DC and AC devices in everyday life

• DC Devices
• Batteries
• Automotive electronics
• Portable electronics
• IPod
• Cellular Phone
• PDA
• Laptop computers
• Desktop computers
• Solar cells
• Computer and memory chips

• AC Devices
• Electric wall outlets
• Household appliances
• High voltage transmission lines
• Electromagnetic transmissions
• Mobile phone signals
• Satellite signals
• Radio signals

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AC Frequency

• Number of complete cycles per unit time
• Units are hertz, Hz
• Units are cycles per second
• Household electrical outlets operate at 60 hertz
  or 60 cycles per second
• Electromagnetic waves operate at much higher
  frequencies

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Sun burn
Heat lamps
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Broadcast Frequencies

• Use of frequencies for broadcast are controlled
  by the Federal Government the FCC - Federal
  Communications Commission
• License required to use a given frequency
• Companies purchase licenses to use these
  frequencies
• Specific bands are setup for all transmissions
• Police/Fire/EMS radio
• Commercial aircraft
• Marine radios
• Mobile phones
• Military applications
• Citizen band radio
• One notable exception is the Unlicensed Band
  (ULB) at 2400 MHz or 2.4 GHz
• Microwave ovens
• Cordless phones
• Bluetooth devices
• Wi-Fi devices
• Any new device can use this frequency provided it
  follows set specifications on power, range, and
  data transmission rates

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Some common frequencies

• AM Radio
• 535 to 1605 KHz
• FM Radio
• 88-108 MHz
• Broadcast TV (not cable TV transmissions which
  are not broadcast but sent via a wire)
• Channels 2-4 54-72 MHz
• Channels 5-6 76-88 MHz
• Channels 7-13 174-216 MHz
• Channels 14-36 470-608 MHz
• Channels 38-69 614-806 MHz
• Older analog phones - 824-894 MHz
• PCS digital phones - 1850-1990 MHz Current
  frequency of operation of most mobile phones
• Bluetooth and Wi-Fi devices - 2400-2497 MHz
• GPS 1575.42 and 1227.60 MHz
• RFID multiple frequencies 860 to 960 MHz very
  common

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Assignment due next class

• HW 2 from the web site
• Write a one page report on How a Cellular Phone
  System Works
• Why is it called cellular?
• Is it really a phone or something else?
• Be sure to include the frequency of operation on
  current cellular phones
• Include at least two references