复旦大学：《计算机网络 Computer Networking》课程教学资源（PPT课件讲稿）Physical Layer Propagation：UTP and Optical Fiber

Physical Layer Propagation UTP and Optical Fiber Chapter 3 Updated January 2007 Panos Business data Networks and Telecommunications. th edition aonoaooonoo Copyright 2007 Prentice-Hal May only be used by adopters of the book

Physical Layer Propagation: UTP and Optical Fiber Chapter 3 Updated January 2007 Panko’s Business Data Networks and Telecommunications, 6th edition Copyright 2007 Prentice-Hall May only be used by adopters of the book

Orientation e Chapter 2 Data link, internet, transport, and application layers Characterized by message exchanges Chapter 3 Physical layer( Layer 1) There are no messages-bits are sent individually Concerned with transmission media, plugs, signaling methods propagation effects Chapter 3: Signaling, UTP, optical fiber, and topologies Wireless transmission is covered in Chapter 5 2

2 Orientation • Chapter 2 – Data link, internet, transport, and application layers – Characterized by message exchanges • Chapter 3 – Physical layer (Layer 1) – There are no messages—bits are sent individually – Concerned with transmission media, plugs, signaling methods, propagation effects – Chapter 3: Signaling, UTP, optical fiber, and topologies – Wireless transmission is covered in Chapter 5

Figure 3-1: Signal and propagation Transmitted Received Signal Signal (Attenuated& Distorted) Propagation Transmission medium Sender Receiver A signal is a disturbance in the media that propagates( travels) down the transmission medium to the receiver If propagation effects are too large, the receiver will not be able to read the received signal 3

3 Figure 3-1: Signal and Propagation Sender Receiver Transmission Medium Propagation Transmitted Signal Received Signal (Attenuated & Distorted) A signal is a disturbance in the media that propagates (travels) down the transmission medium to the receiver If propagation effects are too large, the receiver will not be able to read the received signal

Data Representation

Data Representation

Binary-Encoded data Computers store and process data in binary representations Binary means two There are only ones and zeros Called bits 1101010110001110101100111

5 Binary-Encoded Data • Computers store and process data in binary representations – Binary means “two” – There are only ones and zeros – Called bits 1101010110001110101100111

Binary-Encoded data Non-Binary Data Must be Encoded into Binary Text Integers(whole numbers) Decimal numbers Alternatives(North, South, East, or West, etc. Graphics Human voice Hel→11011001

6 Binary-Encoded Data • Non-Binary Data Must be Encoded into Binary – Text – Integers (whole numbers) – Decimal numbers – Alternatives (North, South, East, or West, etc.) – Graphics – Human voice – etc. Hello 11011001…

Binary-Encoded data Some data are inherently binary 48-bit Ethernet addresses 32-bit IP addresses Need no further encoding 11001o1o OIOI0I0I 001001010100100101( C OOOO、1 I0101001010001O 0101010I01oo1o、4 1001010000010111110 01011010100101O01

7 Binary-Encoded Data • Some data are inherently binary – 48-bit Ethernet addresses – 32-bit IP addresses – Need no further encoding

Figure 3-2: Arithmetic with Binary Numbers Binary Arithmetic for Whole Numbers(Integers) (Counting Begins with 0, not 1) Integer Binary 0 012345678 10 100 101 110 111 1000 There are 10 kinds of people- those who understand binary and those who dont 8

8 Figure 3-2: Arithmetic with Binary Numbers Binary Arithmetic for Whole Numbers (Integers) (Counting Begins with 0, not 1) Integer 0 1 2 3 4 5 6 7 8 Binary 0 1 10 11 100 101 110 111 1000 “There are 10 kinds of people— those who understand binary and those who don’t

Figure 3-2: Arithmetic with Binary Numbers, Continued Binary Arithmetic for Binary Numbers Basic Rules 000 +1 十 1+0 +1+1 =1=1=10=11 9

9 Figure 3-2: Arithmetic with Binary Numbers, Continued Binary Arithmetic for Binary Numbers 1 0 0 1 1 +1 +0 +1 +0 +1 +1 =0 =1 =1 =10 =11 Basic Rules

Figure 3-2: Arithmetic with Binary Numbers, Continued Exam ples Binary Decimal 1000 8 +1 十 =1001 =9 =1010 10 =1011 十 十 100 12 10

10 Figure 3-2: Arithmetic with Binary Numbers, Continued Binary Decimal 1000 8 +1 +1 =1001 =9 +1 +1 =1010 =10 +1 +1 =1011 =11 +1 +1 =1100 =12 Examples