Never before have I witnessed compressed into a

single device so much ingenuity, so much brain

power, so much development, and such

phenomenal results

David Sarnoff

Background Technologies

Telephony

Morse - telegraph

Bell - telephone

Radio

Hertz - generate electromagnetic waves

Marconi - electromagnetic waves and antennas

Armstrong - FM modulation

Vacumn tubes and Amplifiers

Geissler - first vacumn tube

Fleming - vacumn tube diode

Deforest - triode and feedback amplifier

Photoelectric

Phosphoresence, Selenium photoconductive (Ball, Smith)

“kathode” ray tube

Mechanical Television

First television systems LeBlanc (1880) raster scanning John Baird’s Nipkow disk system C. Francis Jenkin’s prismatic ring system Ernst Alexanderson’s mirror drum system

Big problems

1. Mechanical limitations Large, fast spinning disks Holes limited light, resolution (14 scanlines)

2. Detectors Slow: temporal blur Insensitive: bright lights, amplifier

Deployed in Great Britain, US, …

Clever Enhancements

Color

Separate holes in Nipkow

Field sequential

Night

Infrared television

Stereo

Binocular Nipkow disks

Many, many, many mechanical designs

Quote on p. 84

All-Electronic Television

1908 2 synchronized cathode ray tubes (Swinton)

Philo Farnsworth – solo inventor

First demonstration in 1927 in San Francisco

Receiver: Oscillite

Camera: Image Dissector

Vladimir Zworykin – RCA industrial research

Receiver: Kinescope (1929)

Camera: Iconoscope (1931), Orthicon (1933)

World’s Fair demonstration – 343 lines, 60 fields

NTSC 1941, deployment delayed > WWII

Electronic Camera

The key to television was the camera

Key ideas

Photoelectric plate becomes positively charged when exposed to light

Scan the plate with an electron beam, electrons attracted to positive atoms and increases beam current

Major breakthroughs

Electrostatic deflection, deflect before accelerate

Store charge

Low-voltage scan, same-side scan

Amplifier - multipactor

Sawtooth scanning pattern

Color Television

CBS proposed field-sequential color system using a spinning wheel

RCA/NBC system

Color camera - 3 bw cameras w/ dichroic mirrors

Color receiver - 3 beams, phosphors, shadow mask

Signal compatible w/ bw YC perceptual encoding (C less bandwidth)

Color subcarrier

Background to HDTV

Situation 1987

Land-Mobile wanted unused broadcast spectrum; FCC decides in their favor

Broadcasters invent HDTV scenario

NHK demonstration of analog HDTV Analog 1192:60

Satellite broadcast

Used 2 channels (8 Mhz)

Reaction Can’t cede the technology the Japanese

Can’t go with an analog standard

ATSC

FCC Advanced Television Standards Committee

Key competitors:

Zenith and Bell Labs: 8-VSB and progressive

General Instruments and MIT: digital (mpeg)

Philips, Sarnoff (RCA), Thomson

1993 Grand Alliance formed

1996 Telecommunications Act

Simulcast: digital and analogy

Loan 2nd channel through 2004(?)

Experiment w/ different video/data formats

Broadcasters vs. Computers

War between computer companies/broadcasters

Major issues: Square pixels Interlaced vs. progressive Resolution and formats Flexible multimedia formats Datacasting Deployment rate Convergence

Analog to digital a bigger transition than

Mechanical to eletronic!