1. Chapter 7: Communications Technology
Networks and Communications

2. Key Questions
How do digital and analog data differ, and what does a modem do?
What are some offerings of new telecommunications?
What the types of wired and wireless channels and some types of wireless communications
What are the benefits of networks, and what are their types, components, and variations?
What are important issues in cyberethics

3. I. Using Computers to Communicate
A. Analog Signals: Continuous Waves
B. Digital Signals: Discrete Bursts
C. The Modem: Today’s Compromise
D. Choosing a Modem 1. External versus internal 2. Transmission speed
E. Communications Software

4. Analog and digital signals

5. How modems work

6. I. Using Computers to Communicate
F. Transmission media
1.ISDN lines 2.DSL (ADSL) 3.T1 Lines 4.Cable modems 5.Satellite dishes
Bandwidth
Amount of info transmitted within a given period of time
Broadband: high speed connections

7. Connection competitors
Approximate time to transfer a 40MB file

8. II. Communications Channels
A. Twisted-Pair Wire
B. Coaxial Cable
C. Fiber-Optic Cable
D. Microwave & Satellite Systems
E. Other Wireless Communications   a. GPS (Global Positioning System) b. Pagers

9. Three types of wired communications channels
Twisted-pair wire (top right):
poor protection against electrical interference.
Coaxial cable (top left):
better protection against electrical interference.
Fiber-optic cable (bottom left):
Thin glass strands transmit light
These strands can carry computer and
voice data over long distances.

10. Microwave systems

11. Communications satellite

12. GPS receiver: handheld compass

13. Data Compression Removing repetitive patterns to reduce the size
Lossless compression: Compressed data can be decompressed back to the same original – MS Word and Excel files, etc
Lossy compression: loss of accuracy for a high degree compression – graphics and video files
Compression Standard:
Joint Photographic Experts Group (JPEG): for still images (file extension: .jpeg or .jpg)
Motion Picture Experts Group (MPEG): for moving images (file extension: .mpeg or .mpg)

14. III. Communications Networks
A. Types of Networks  1. Wide area network (WAN) 2. Metropolitan area network (MAN) 3. Local area network (LAN)
B. Network Operating Systems
C. Hosts & Nodes, Servers & Clients

15. IV. Local Networks A. Types of LANs 1. Client/Server 2. Peer-to-Peer
B. Components of a LAN 1. Connection or cabling system 2. Microcomputers with interface cards 3. Network operating system 4. Other shared devices 5. Bridges, routers, and gateways

16. Components of a typical LAN

17. IV. Local Networks
D. Topology of LANs 1. Star network 2. Ring network 3. Bus network

18. Star Network

19. Ring network

20. Bus network

21. Serial data transmission

22. Parallel data transmission
Data resembles cars moving in separate lanes
at the same speed on a multilane freeway.