Wireless technologyWireless technology

Evolving technology

1895 -present

By

A.L. Wicks

Department of Mechanical EngineeringVirginia Tech

Wireless TechnologyWireless Technology

Internet market for just the US

Wireless TechnologyWireless Technology

Global Internet market

Wireless TechnologyWireless Technology

US wirelessmarket

Wireless TechnologyWireless Technology

Global wirelessmarket

Wireless TechnologyWireless TechnologyA Brief HistoryA Brief History

Spark transmitter- Hertz

First successful transmitter and receiver in 1895 - Marconi

Presented in Transactions AIEE1897

First transatlantic voice communication Marconi 1900

Wireless TechnologyWireless Technology

Golden Age of Radio

Ship to ship, Ship to shore

1912 Sinking of the Titanic

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Golden Age of RadioFirst commercial stations 1912

WTG Manhattan KansasWGY Schenectady NY

By 1920WBZ BostonWHO DesMoinesKDKA Pittsburgh

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Frequency BandsControlled by the FCCSets AM commercial radio band

FM band commercial radio bandLimits power example AM radio limited to 50K watts

Sets TV bandNavigation bands Civil defenseEmergency bandsBeacons

ISM bands industrial scientific medical bands915 MHz 2.4 GHz

Wireless TechnologyWireless TechnologyELF

Frequency allocation chart AM

FM

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TV 2-4

TV 5-6

Wireless TechnologyWireless TechnologyFunction of wavelength C=3x108 m/sec

ie 2m

10m40m70m80m

Amateurradio

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The Old Way( Conventional Broadcasting)The Old Way( Conventional Broadcasting)Narrow bandNarrow bandDirectly modulate the signal (FM / AM)Directly modulate the signal (FM / AM)NegativesNegatives

Poor dynamic range / linearityPoor dynamic range / linearityNo recovery from interferenceNo recovery from interference“Dumb”“Dumb”

PositivesPositivesReal TimeReal TimeSimpleSimple

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The New Way The New Way --Wireless Area Networks (WANs)Wireless Area Networks (WANs)DigitalDigital

Digitize, buffer, transmitDigitize, buffer, transmitLocally process and reduceLocally process and reduce

Spread SpectrumSpread SpectrumFHSSFHSSDSSSDSSS

BandsBandsISM, 2.4 GHz +ISM, 2.4 GHz +

SmartSmart

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Spread Spectrum MethodsSpread Spectrum MethodsDSSSDSSS

Direct Sequence Spread SpectrumDirect Sequence Spread SpectrumModulating function is pseudo random sequenceModulating function is pseudo random sequenceFairly expensive powerFairly expensive power--wise to implementwise to implement

FHSSFHSSFrequency Hop Spread SpectrumFrequency Hop Spread SpectrumRadio Hops to pseudo random channelRadio Hops to pseudo random channelFairly inexpensive powerFairly inexpensive power--wise to implementwise to implement

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Spread Spectrum MethodsSpread Spectrum MethodsPatented in 1941 2,292,387Patented in 1941 2,292,387

‘Secret Communication System’‘Secret Communication System’HedyHedy Markey and George Markey and George AntheilAntheil

Better known as Better known as HedyHedy LamarrLamarr, , ZiegfridZiegfrid GirlsGirls

To make a contribution to the war effort To make a contribution to the war effort Torpedoes were being jammedTorpedoes were being jammed

Wireless TechnologyWireless Technology

Spread Spectrum MethodsSpread Spectrum MethodsConsider a player pianoConsider a player pianoSync the two rolls to play the same songSync the two rolls to play the same songUse the notes of the song to preprogram the carrier Use the notes of the song to preprogram the carrier

frequenciesfrequencies

Patent suggested 88 frequenciesPatent suggested 88 frequencies

Ms Ms LamarrLamarr died 1/19/2000 at the age of 86died 1/19/2000 at the age of 86