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!