Communication

1
Communication

• An electronic technology perspective

2
Overview of mass media

• Communication medium is anything that can carry
  and transmit information among human beings.
• Anything could be
• bone (very ancient Chinese words)
• Stone (ten commandments)
• bamboo (ancient Chinese books)
• Paper (books, newspapers, magazines)
• Electronic technology radio, TV, phone,
  internet, CD
• Information could be
• text, picture, sound (speech, music)

3
Wireless communication
By sound wave (f20Hz20KHz, v343m/s)
By radio/microwave (f500k200MHz, v300,000km/s)
4
Electromagnetic spectrum
5
Frequency bands
6
Bands
A band is a small section of the spectrum of
radio communication frequencies, in which
channels are usually used or set aside for the
same purpose. Examples include AM broadcast
band (5301610 kHz) Various Shortwave bands
(5.926.1 MHz) Television stations 26
(5488 MHz in the Americas) FM broadcast band
(88108 MHz, except 7690 MHz in Japan) Airband
(108137 MHz) for air traffic control Television
stations 713 (174216 MHz in the Americas) L
band (1,4521,492 MHz) for digital radio (DAB)
outside the United States Military bands FM
band (35-87.9 MHz) X band (810 GHz) S band
(17502400 MHz) K band (2040 GHz), which is
further subdivided Ka band K-above band,
2740 GHz, mainly used for radar and general
communications Ku band K-under band,
1218 GHz, mainly used for satellite
communications Radio navigation beacons, such as
GPS
7
Radio

• Use relatively low frequency for sound message
  transmission
• AM amplitude modulation
• FM frequency modulation
• Short wave
• Satellite radio
• Band
• AM broadcast band (5301610 kHz)
• Various Shortwave bands (5.926.1 MHz)
• FM broadcast band (88108 MHz, except 7690 MHz
  in Japan)

8
TV

• Use relatively high frequency for both picture
  and sound transmissions.
• Band
• Television stations 26 (5488 MHz in the
  Americas)
• Television stations 713 (174216 MHz in the
  Americas)

9
Internet

• The Internet is a collection of interconnected
  computer networks, linked by copper wires,
  fiber-optic cables, wireless connections, etc.
• In contrast, the World Wide Web is a collection
  of interconnected documents and other resources,
  linked by hyperlinks and URLs.
• The World Wide Web is one of the services
  accessible via the Internet, along with various
  others including e-mail, file sharing, online
  gaming and others.

10
History of Internet

• The research on Internet started in 1950s
• Commercial networks began in 1980s
• Internet gained public face in 1990s
• 1991, www project
• Web browser Mosaic (1993), Netscape, internet
  explorer
• As of September 30, 2007, 1.244 billion people
  use the Internet
• English(31),Chinese (16), Spanish (9),Japanese
  (7), German (5),French (5)
• Asia(37), Europe(27),North America(19), and
  Latin America(9)

11
Common uses of Internet

• Email private communication
• World Wide Web
• Publish information
• Search engine yahoo, google
• Advertising
• E-commerce buy/sale through internet
• Remote access working from home
• File sharing attachment in email, upload to
  website
• Streaming media (audio/video) web cams, video
  chat rooms, video conference, YouTube
• Voice technology (VoIP)
• Internet access
• dial-up, broadband, Wi-Fi, satellite, cell phones

12
Impacts of internet

• Positive
• Make communication easy and fast
• Make life colorful (picture and music)
• Share information (database)
• Easy shopping
• Negative
• Security problem your SSN, bank account
• Internet-based crimes
• Addict into a virtual world
• Child pornography or violence
• Make people too busy