HomeworkHomework Final Exam Final Exam

Wednesday, 3 May, 5:30-7:20 pmWednesday, 3 May, 5:30-7:20 pm Readings:Readings:

[22] “Digital TV in the U.S.”[22] “Digital TV in the U.S.”[23] “HDTV: The Great Picture isn’t the[23] “HDTV: The Great Picture isn’t the

Whole Picture”Whole Picture”[24] “Cable Modems: Cable TV Delivers[24] “Cable Modems: Cable TV Delivers

the Internet”the Internet”[25] “Bringing Home the Internet”[25] “Bringing Home the Internet”

Final ExamFinal Exam

Work 5 of 7 pagesWork 5 of 7 pages 2-3 pages will be from the Fall ‘992-3 pages will be from the Fall ‘99 finalfinal Articles = 1 Letter GradeArticles = 1 Letter Grade Memory dump Memory dump pertinent informationpertinent information in the space provided in the space provided

Start Studying Now!

Cellular FlavorsCellular Flavors Cellular Digital Packet Data (CDPD)

AMPS/TDMA overlay network Moves data at speeds < 19.2 Kbps Gappy coverage

Packet Radio (Wireless WAN’s) Proprietary packet networks capable of moving data at speeds

< 19.2 Kbps Two U.S. networks with somewhat gappy coverage

Ardis Bell South Wireless Data

Cellular FlavorsCellular Flavors

Wireless LAN’s (IEEE 802.11) Speeds from 1 Mbps to 11 Mbps Small Cells

Note drastic mobile data speed drop from LAN’s to WAN

Other non-CellularLong-Distance Wireless OptionsOther non-CellularLong-Distance Wireless Options

Geosynchronous Satellite Links &Point-to-Point Microwave Links (see [12]) Requires directional antenna Speeds < 45 Mbps are common Generally operate from fixed sites

Future Status of CellularFuture Status of Cellular

Higher data speeds Higher data speeds Heavier use of micro-cellsHeavier use of micro-cells Use of Low Earth Orbiting SatellitesUse of Low Earth Orbiting Satellites

Iridium: multi-billion dollar fiascoIridium: multi-billion dollar fiasco 66 LEOS satellites66 LEOS satellites focused on voice telephonyfocused on voice telephony Bankrupt & shut-down on March 17, 2000Bankrupt & shut-down on March 17, 2000 Casts a pall over all LEOS operationsCasts a pall over all LEOS operations

RIP

Future Status of CellularFuture Status of Cellular Selected LEOS SystemsSelected LEOS Systems

GlobalstarGlobalstar 48 LEOS’s48 LEOS’s focuses on voicefocuses on voice Simpler design than IridiumSimpler design than Iridium In operation nowIn operation now

TeledesicTeledesic 288 LEOS’s288 LEOS’s Aimed at dataAimed at data Target operational date is 2004Target operational date is 2004

NTSC TVNTSC TV Interlaced ScanningInterlaced Scanning 4 to 3 Aspect ratio4 to 3 Aspect ratio 525 Scan Lines in a Frame, 485 Active525 Scan Lines in a Frame, 485 Active Video Bandwidth 4.2 MHzVideo Bandwidth 4.2 MHz

Composite SignalComposite Signal(Luminance + Chrominance)(Luminance + Chrominance)

RF Bandwidth 6.0 MHzRF Bandwidth 6.0 MHzAM modulated VideoAM modulated VideoFM Modulated VoiceFM Modulated VoiceGuard BandGuard Band

Monochrome NTSC TVMonochrome NTSC TV

Pick-Up Element

Ele

ctro

nic

s

Monochrome Signal

Phosphor Screen

Electron Beam

Control Magnets

Control Grid

ElectronGun

Transmitter

Receiver

The signal from the Pick-Up element is transmitted, processed, and fedto the receiver’s Control Grid.

Color NTSC TVColor NTSC TV Three Pickup Element RGB CameraThree Pickup Element RGB Camera Luminance Signal Luminance Signal Backwards Backwards

Compatible with B&W setsCompatible with B&W sets Color Color Chrominance Signal Chrominance Signal causescauses

controlled distortion on B&W setscontrolled distortion on B&W sets Color Monitor has 3 beams & Color Monitor has 3 beams &

thousands of colored phosphor dotsthousands of colored phosphor dots

Color NTSC TVColor NTSC TV

Ele

ctro

nic

s

B&W compatibleLuminance Signal

3 Pick-Up Elements

CCD’s

R

G

B

TRANSMITTER

High-FrequencyChrominance Signal

CompositeSignal

Color NTSC TVColor NTSC TV

Ele

ctro

nic

s

B&W compatibleComposite Picture

R

G

B

RECEIVER

3 Electron Beams

Phosphor Dots

Video...Video... Intra-TV Studio video is typically locked

to a local clock Inter-TV Studio video

is plesiochronously timed Time Base Correctors (elastic stores)

smooth out the differences The video inside (& outside) a TV Studio is

sometimes carried as an analog signal and sometimes carried as a digital bit stream