?????? ?????????? The Physical Layer - PowerPoint PPT Presentation

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Title:

?????? ?????????? The Physical Layer

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Chapter 2 The Physical Layer – PowerPoint PPT presentation

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Title: ?????? ?????????? The Physical Layer


1
?????? ?????????? The Physical Layer
  • Chapter 2

2
????? ????? ??????? Guided Transmission Data
  • Magnetic Media ??????? ???????????
  • Twisted Pair ??? ??????? ????????
  • Coaxial Cable ???????? ????????
  • Fiber Optics??????? ???????

3
??? ??????? ???????? Twisted Pair
  • (a) Category 3 UTP.
  • (b) Category 5 UTP.

4
???????? ???????? Coaxial Cable
  • A coaxial cable.

5
??????? ??????? Fiber Optics
  • (a) Three examples of a light ray from inside a
    silica fiber impinging on the air/silica boundary
    at different angles.
  • (b) Light trapped by total internal reflection.

6
Transmission of Light through Fiber
  • Attenuation of light through fiber in the
    infrared region.

7
??????? ???????? Fiber Cables
  • (a) Side view of a single fiber.
  • (b) End view of a sheath with three fibers.

8
Fiber Cables (2)
  • A comparison of semiconductor diodes and LEDs as
    light sources.

9
Fiber Optic Networks
  • A fiber optic ring with active repeaters.

10
Fiber Optic Networks (2)
  • A passive star connection in a fiber optics
    network.

11
????? ??????? Wireless Transmission
  • The Electromagnetic Spectrum ????? ??????????
  • Radio Transmission ??????? ??????? ???????
  • Microwave Transmission ??????? ???????? ?????????
  • Infrared and Millimeter Waves??????? ??? ???????
    ? ???????????
  • Lightwave Transmission??????? ???????? ???????

12
The Electromagnetic Spectrum
  • ????? ????????? ? ????????? ?? ?????????

13
Radio Transmission
  • (a) ?? ???????? ??????? LF ? ???????? ??? VLF ?
    ???????? MF ???? ??????? ????????? ?????? ???
    ?????.
  • (b) ?? ???????? ??????? HF ????? ????? ?? ????
    ??????????

14
Lightwave Transmission
  • ???? ?? ?????? ?????? ????? ??????? ?? ?????
    ????????? ??????? ??????? ? ???? ????? ???? ?????
    ????? ????? ???????.

15
????? ?????? ?????? ??? ??????? Public Switched
Telephone System
  • Structure of the Telephone System???? ??????
    ???????
  • The Local Loop Modems??????? ??????? ????????

16
???? ?????? ??????? Structure of the Telephone
System
  • (a) ???? ????? ???? ????.
  • (b) ???? ?????.
  • (c) ???? ????? ??? ??????? ( ?????? ???????
    ????? ??????? ?????? ??????? ??????? ????????
    ???????? ????? ??????? ??????).

17
???? ?????? ??????? Structure of the Telephone
System (2)
  • ???? ????? ????? ????? ???????.

18
??????? ??????? ?????????? ADSL? ? ??????? The
Local Loop Modems, ADSL, and Wireless
  • ??????? ????? ???????? ? ?????? ??????? ???
    ???????? ??????? ??? ?????? ????????? ? ????????.

19
Modems ?????????
  • (a) ????? ??????.
  • (b) ????? ?????.
  • (c) ????? ?????.
  • (d) ????? ????.

20
?????? ?????
21
?????? RS232-C
DTE
DCE
25 PIN D-SUB MALE at the DTE (Computer). 25 PIN
D-SUB FEMALE at the DCE (Modem).
22
ISDN???? ??????
23
????? ????????? Paging Systems
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