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

Pointy Haired Boss saves a million

Various electronic devices similar to a watch

Where there is a need, an engineer will come up with a solution

Mobile internet access via satellite using pedal powered electric generator

Transistors are the building block of all electronics. As the manufacturing cost comes down, electronics become very cheap.

AC vs. DC CircuitsAC vs. DC Circuits

DC and AC devices in everyday lifeDC and AC devices in everyday life

DC DevicesDC Devices• BatteriesBatteries• Automotive electronicsAutomotive electronics• Portable electronicsPortable electronics

IPodIPod Cellular PhoneCellular Phone PDAPDA

• Laptop computersLaptop computers• Desktop computersDesktop computers• Solar cells• Computer and memory Computer and memory

chipschips

AC DevicesAC Devices• Electric wall outletsElectric wall outlets• Household appliancesHousehold appliances• High voltage High voltage

transmission linestransmission lines• Electromagnetic Electromagnetic

transmissionstransmissions Mobile phone signalsMobile phone signals Satellite signalsSatellite signals Radio signalsRadio signals

AC Frequency AC Frequency

Number of complete cycles per unit Number of complete cycles per unit timetime

Units are hertz, HzUnits are hertz, Hz Units are cycles per secondUnits are cycles per second Household electrical outlets operate Household electrical outlets operate

at 60 hertz or 60 cycles per secondat 60 hertz or 60 cycles per second Electromagnetic waves operate at Electromagnetic waves operate at

much higher frequenciesmuch higher frequencies

Sun burn

Frequency Allocations

Broadcast FrequenciesBroadcast Frequencies Use of frequencies for broadcast are controlled Use of frequencies for broadcast are controlled

by the Federal Government – the FCC - Federal by the Federal Government – the FCC - Federal Communications CommissionCommunications Commission

License required to use a given frequencyLicense required to use a given frequency Companies purchase licenses to use these Companies purchase licenses to use these

frequenciesfrequencies Specific bands are setup for all transmissionsSpecific bands are setup for all transmissions

• Police/Fire/EMS radioPolice/Fire/EMS radio• Commercial aircraftCommercial aircraft• Marine radiosMarine radios• Mobile phonesMobile phones• Military applicationsMilitary applications• Citizen band radioCitizen band radio

Typical Typical large large

broadcast broadcast antennaantenna

Very tall, often on mountains, to transmit over long distances

Some common frequenciesSome common frequencies AM RadioAM Radio

• 535 to 1605 KHz 535 to 1605 KHz FM RadioFM Radio

• 88-108 MHz88-108 MHz Broadcast TV (old)- requires external antennaBroadcast TV (old)- requires external antenna

• Channels 2-4 54-72 MHzChannels 2-4 54-72 MHz• Channels 5-6 76-88 MHzChannels 5-6 76-88 MHz• Channels 7-13 174-216 MHzChannels 7-13 174-216 MHz• Channels 14-36 470-608 MHzChannels 14-36 470-608 MHz• Channels 38-69 614-806 MHzChannels 38-69 614-806 MHz

Today, most TV transmissions are digitized and Today, most TV transmissions are digitized and sent via cable, fiber optics, or satellitesent via cable, fiber optics, or satellite

Broadcast FrequenciesBroadcast Frequencies One notable exception is the Unlicensed Band

(ULB) at 2400 MHz or 2.4 GHz, also known as the Industrial, Scientific, and Medical band• Microwave ovensMicrowave ovens• Cordless phonesCordless phones• Bluetooth devicesBluetooth devices• Wi-Fi devicesWi-Fi devices• Any new device can use this frequency Any new device can use this frequency

without a FCC license provided it follows set without a FCC license provided it follows set specifications on power, range, and data specifications on power, range, and data transmission ratestransmission rates

A second band at 5.0 GHZ is also available but A second band at 5.0 GHZ is also available but has limited use due to a lack of inexpensive has limited use due to a lack of inexpensive chips that operate at 5.0 GHzchips that operate at 5.0 GHz

Wireless frequencies for the EE Wireless frequencies for the EE projectproject

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 (2.4 – 2.497 GHz)

GPS – 1575.42 and 1227.60 MHz RFID – multiple frequencies – 860 to 960

MHz very common

Assignment due next classAssignment due next class

HW #3 from the web siteHW #3 from the web site• Write a one page report on “How a Write a one page report on “How a

Cellular Phone System Works”Cellular Phone System Works”• Why is it called “cellular”?Why is it called “cellular”?• Is it really a phone or something else?Is it really a phone or something else?• Be sure to include the frequency of Be sure to include the frequency of

operation on current cellular phonesoperation on current cellular phones• Include at least two referencesInclude at least two references