1. Chapter 4. Transmission Media
Guided Transmission Media
Unshielded and Shielded Twisted pair
Coaxial cable
Optical Fiber
Wireless Media
Terrestrial Microwave
Satellite Microwave
Broadcast Radio
Infrared

2. Data Transmission System
Key concerns
Data rate and Distance
Design Factors
Bandwidth
Transmission impairments
Interference
Number of receivers

3. Electromagnetic Spectrum

4. Characteristics of Guided Media
Frequency Range
Typical Attenuation
Typical Delay
Repeater Spacing
Twisted pair
(w/ loading)
0 to 3.5 kHz
0.2 1kHz
50 ms/km
2km
(multi-pair cables)
0 to 1 MHz
3 1kHz
5 ms/km
Coaxial cable
0 to 500 MHz
7 10MHz
4 ms/km
1 ~ 9 km
Optical fiber
180 to 370 THz
0.2 ~ 0.5 dB/km
40km

5. Twisted Pair Twisting Reduces low-frequency interference
Use of different twist length in adjacent pairs reduces crosstalk

6. Twisted Pair (cont) STP: Shielded Twisted Pair
reduce interference
EIA-568A: by Electronic Industries Association, 1991, 1995
Category 3: up to 16 MHz
3 ~ 4 twists per foot (7.5 ~ 10cm)
Category 4: up to 20 MHz
Category 5: up to 100 MHz
3 ~ 4 twists per inch (0.6 ~ 0.85cm)

7. Coaxial Cable
Up to 400 MHz
Outer conductor

8. Optical Fiber

9. Comparison Table 3.1 Point-to-Point Transmission Characteristics
of Guided Media Transmission
Medium Total Data Rate Bandwidth Repeater Spacing
Twisted Pair Mbps MHz to 10 km
Coaxial Cable Mbps MHz to 10 km
Optical Fiber Gbps GHz to 100 km

10. Unguided Media via antenna Terrestrial Microwave Satellite Microwave
2 GHz ~ 40 GHz
Satellite Microwave
Optimal frequency range: 1 GHz ~ 10 GHz
Broadcast Radio
30 MHz ~ 1 GHz
Infrared
3x1011 ~ 2x1014 Hz