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Chapter 7 Transmission Media. Guided Media Unguided Media. The McGraw-Hill Companies, Inc., 1998. WCB/McGraw-Hill. Figure 7-1. Electromagnetic Spectrum. The McGraw-Hill Companies, Inc., 1998. WCB/McGraw-Hill. Figure 7-2. The McGraw-Hill Companies, Inc., 1998. WCB/McGraw-Hill.
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Chapter 7Transmission Media • Guided Media • Unguided Media The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-1 Electromagnetic Spectrum The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-2 The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-3 The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Twisted-Pair Cable Figure 7-4 and 7-5 The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-6 Effect of Noise on Parallel Lines The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-7 Noise on Twisted-Pair Lines The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-8 Unshielded Twisted-Pair Cable The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-9 UTP Connectors The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-10 Shielded Twisted-Pair Cable The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Coaxial Cable Figure 7-11 and 7-12 The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-13 Refraction The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-14 Critical Angle The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-15 Reflection The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-16 The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-17 Multimode Step-Index The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-18 Multimode Graded-Index The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-19 Single Mode The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-20 Fiber Construction The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-21 Radio Communication Band The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-22 Propagation Types The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-23, 24 VLF LF The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-25, 26 MF HF The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-27, 28 VHF UHF The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-29, 30 SHF EHF The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-31 Terrestrial Microwave The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-32 Parabolic Dish Antenna The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-33 Horn Antenna The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-34 Satellite Communication The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-35 Geosynchronous Orbit The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Cellular System Figure 7-36 The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Figure 7-37 Cellular Bands The McGraw-Hill Companies, Inc., 1998 WCB/McGraw-Hill
Transmission Impairment • Attenuation • Loss of energy • Caused by resistance • dB = 10log10 Pout/Pin • -3dB is loss of half power + 3dB is double
Distortion • Changes from original shape • Only occurs in composite signals • Each signal component has it’s own propagation speed
Noise • Thermal noise – White noise • Caused by random movement of electrons • Induced noise • Broadcast by motors, appliances etc. • Crosstalk • Signal on one wire being received by parallel wire • Impulse • Spike – High energy, short duration
Performance • Throughput • Propagation Speed • Propagation Time
Throughput • Measurement of how fast data can pass through a point
Propagation Speed • Distance a signal can travel through a medium in one second • Light in a vacuum 3 * 108 m/s • Almost same in twisted pair cable • Coax and Fiber 2 * 108 m/s for frequencies in MHz to GHz range
Propagation Time Propagation Time = distance / propagation speed Twisted Pair = 1000m/(3 * 108 m/s) = 3.33 us/km Coax | Fiber = 1000m/(2 * 108 m/s) = 5 us/km
Wavelength How Far signal travels in a period of time Wavelength = Propagation * Period • l= c/f • Red light in air f = 4*1014 • AIR = (3 * 108) / (4 * 1014) = .75 um • Coax/fiber = (2 * 108) / (4 * 1014) = . 5 um
Shannon Capacity • Theoretical maximum channel capacity • C = Blog2 (1 + S/N) B = bandwidth S = signal strength N = noise level • Almost never reached
Shannon Capacity • C = Blog2 (1 + S/N) • Phone line example • B = 3300 – 300 = 3000 • S/n = 35db = 3162 • C = 3000 log2 (1 + 3162) = 3000 log2 (3163) • = 3000 * 11.62 = 34860 bps
Media Comparisons • Cost • Speed • Attenuation • EMI • Security • See Table 7.3 pg 218