1. 0’s and 1’s: Voice, Video and Data as Digital Bits: The Technical Nuts and Bolts of Networks Virginia Franke Kleist, Ph.D. West Virginia University February 12, 2002

2. Main Points for Today: Understand how networks can carry different kinds of signals: Voice, video and data Networks can convert different types of signals back and forth Media are the physical “pipes” over which voice, video and data travel Understand a map of how the Internet might look with voice, video and data

3. Conceptual View of Network Fascinating time in history Technologies of voice converging with technologies of data Big growth in use of the internet Major developments in technologies of the internet Major developments in media technologies (wireless, microwave, low earth orbiting satellites, m-commerce, GPS devices)

4. What are the different components of a network? Internet is a network of millions of computers linked together all over the world PSTN is a network of millions of telephones linked together all over the world These networks have become interchangeable Want to understand the nuts and bolts of networks

5. Digital Codes Digital signal is an on/off pulse of light or electricity that represents a piece of information Two discrete states: 1 bit is on, 0 bit is off Used in data communications Sample codes are ASCII and EBCDIC, use 7 or 8 bits to represent letters and numbers with 0’s and 1’s

6. Analog Signal An analog signal is a continuously varying electromagnetic waveform that is representative or analogous to one’s voice Varies in amplitude (loud or soft) Varies in pitch (high or low) Original waveforms were sent in 1886 by Alexander Graham Bell to Mr. Watson, technology is much the same today

7. A to D and D to A Conversion: Digital to analog conversion is done by a modem. Need to do this so that your computer can work in analog world to get to your internet service provider Analog to digital conversion is done by a codec, and allows voice, video or music to be transported either over the internet or on high speed digital pipes

8. Media Fiber optic cable Transatlantic cable Microwave towers Low earth orbiting satellites Cellular telephone Copper cable ADSL, DSL, cable modems and modems

9. Switching Circuit switching is used when a “pipe” is opened from one end to the other for the entire transaction, like a phone call Packet switching is used to efficiently pack the “pipes” by cutting up the data or voice into lots of little packets, and routing these around on the internet

10. Conclusions Technologies of voice, video and data have converged on the internet Seeing voice riding on the internet, email on the voice network, streaming video via packets MP3s, streaming video, voice over IP, internet radio What is next?