演示文稿通信原理英文版
通信原理 英文
通信原理英文Communication PrinciplesCommunication principles refer to the fundamental concepts and theories that govern the process of transmitting information from one entity to another. These principles form the foundation of effective communication and play a crucial role in various communication systems, such as wireless communication, optical communication, and digital communication.One of the key communication principles is the concept of encoding and decoding. Encoding involves converting the information into a suitable form for transmission, while decoding involves the reverse process of converting the received signals back into meaningful information. This principle ensures that the information is accurately transmitted and understood by the receiving entity.Another important principle is the concept of modulation. Modulation is the process of modifying a carrier signal by varying its amplitude, frequency, or phase to carry the information. This principle is used in various communication systems to transmit information over long distances without significant loss or distortion.Furthermore, the principle of noise reduction is crucial in communication systems. Noise refers to any unwanted disturbance that affects the quality of the transmitted signal. To ensure reliable and clear communication, noise reduction techniques, such as filtering and error correction, are employed to minimize the impactof noise on the received signals.Additionally, the principle of multiplexing allows multiple signals to be transmitted over a single communication channel. This is achieved by dividing the channel bandwidth into smaller sub-channels, each carrying a different signal. Multiplexing enables efficient utilization of the available communication resources and allows for simultaneous transmission of multiple signals.Furthermore, the principle of synchronization is essential for successful communication. Synchronization ensures that the transmitting and receiving entities are operating in a coordinated manner, allowing for accurate transmission and reception of the information. Various techniques, such as clock synchronization and frame synchronization, are employed to achieve synchronization in communication systems.Lastly, the principle of error detection and correction is crucial for reliable communication. Error detection techniques, such as checksums and parity bits, are used to identify errors in the transmitted signals. Error correction techniques, such as forward error correction codes, are employed to correct the detected errors and ensure accurate transmission and reception of the information. In summary, communication principles are fundamental concepts and theories that govern the process of transmitting information. These principles, such as encoding and decoding, modulation, noise reduction, multiplexing, synchronization, and error detection and correction, ensure efficient and reliable communication in various communication systems.。
通信原理(英文版)
2.1 Classification of Signals
2.1.1 Deterministic signals and random signals
• What is deterministic signal? • What is random signal?
2.1.2 Energy signals and power signals
f (t) f (t T) t
Its frequency spectrum is
/2
C( jn0 )
1 T
/ 2 Ve j n0t dt
/ 2
1 T
V
jn 0
e
j n0 t
/ 2
V e j n0 / 2 e j n0 / 2
f (t) sin(t) Its frequency spefct(rtu)m: f (t 1)
0 t 1 t
C(
jn 0 )
1 T0
T0 / 2 s(t )e jn0t dt
T0 / 2
1 sin(t )e j 2nt dt
Solution: Let the expression of the rectangular pulse be
Then its frequency spectral density is
its
Fourier
tragns(fto)rm:
1
0
t /2 t /2
G() / 2 e jt dt 1 (e j / 2 e j / 2 ) sin( / 2)
通信原理怎么说英语作文
通信原理怎么说英语作文Communication Principles。
Communication is the process of exchanging information, ideas, and feelings between individuals or groups. It plays a crucial role in our daily lives, enabling us to connect with others, share knowledge, and express ourselves. Inthis essay, we will explore the principles of effective communication and how they contribute to building strong relationships and achieving successful outcomes.Firstly, one of the key principles of communication is clarity. It is essential to convey information in a clear and concise manner, using simple and understandable language. Ambiguity and confusion can lead to misunderstandings and hinder effective communication. Therefore, individuals should strive to express their thoughts and ideas in a straightforward and unambiguous way.Another important principle is active listening.Effective communication is a two-way process, where both the speaker and the listener play an active role. Active listening involves paying full attention to the speaker, understanding their message, and providing feedback. By actively listening, we can better comprehend the speaker's intentions, feelings, and needs, thereby strengthening the communication process.Moreover, non-verbal communication is a powerful tool that complements verbal communication. Non-verbal cues such as facial expressions, body language, and gestures can convey emotions and attitudes. For instance, a smile can indicate friendliness and openness, while crossed arms may signal defensiveness or disagreement. Being aware of these non-verbal signals can help us interpret the underlying messages and enhance our overall understanding.Furthermore, empathy is an essential aspect ofeffective communication. Empathy involves understanding and sharing the feelings of others. By putting ourselves in someone else's shoes, we can better relate to their experiences and perspectives. This understanding allows usto communicate with compassion and sensitivity, fostering trust and building stronger relationships.In addition, feedback is a vital component of effective communication. Providing constructive feedback helps to clarify expectations, address concerns, and improve performance. It is important to give feedback in arespectful and non-threatening manner, focusing on specific behaviors or actions rather than personal attacks. By offering feedback, we can encourage growth and developmentin both personal and professional relationships.Lastly, cultural awareness is crucial in today's globalized world. Different cultures have unique communication styles, norms, and values. Being mindful of these cultural differences can prevent misunderstandingsand facilitate effective communication. It is important to respect and appreciate diverse perspectives, adapting our communication approach to accommodate cultural variations.In conclusion, effective communication is essential in all aspects of life. By following the principles of clarity,active listening, non-verbal communication, empathy, feedback, and cultural awareness, we can establish meaningful connections, resolve conflicts, and achieve successful outcomes. Communication is a skill that can be developed and improved upon, and by practicing these principles, we can become more effective communicators.。
现代通信原理课件(英文版)(ppt 35页)
from a digital source to the intended receiver(sink) 5. Analog communication system transfers
2) Note: The general principles of digital and analog modulation apply to all types of channels, although channel characteristics may impose constraints that favor a particular type of signaling
15
1.2 Digital and Analog source and system
2 the advantage of digital system
1）Relatively inexpensive digital circuits may be used
2） Privacy is preserved by using data encryption
8
1.2 Digital and Analog source and system
• The generation of communication system
Information input m(t)
Signal processing
Carrier circuits
Transmitter
channel noise
1. Selection of the information-bearing
通信原理(英文版)
【Example 2.4】Find the waveform and the frequency spectral density of a sample function. Solution: The definition of the sample function is
sin t Sa ( t ) t
d(t)
1
(f)
0
t
0
f
meaning of d function: It is a pulse with infinite height, infinitesimal width, and unit area. Sa(t) has the following property:
Physical
F ( ) lim
/2 / 2
cos 0 te
jt
sin[( 0 ) / 2] sin[( 0 ) / 2] dt lim 2 ( ) / 2 ( ) / 2 0 0
The frequency spectral density of d(t):
( f ) d (t )e
jt
d (t ) 0
t 0
dt 1 d (t )dt 1
7
d(t)
and its frequency spectral density:
f (t ) f (t 1) t
1
Its frequency spectrum:
1 C ( jn 0 ) T0
T0 / 2
T0 / 2
s(t )e
无线通信原理双语lecture.ppt
2019/12/18
16
WLAN Infrastructure
•Network between devices in home and office environment; •Typically gives access to a fixed infrastructure
• Cognitive and Software Defined Radio,
IEEE 802.22(proposed), et al
Area, …
The output of Wireless System Modeling and Design: International standard (IP): 802.11,802.16,GSM…
2019/12/18
17
1.5 WPANs and WMANs
WPANs: Wireless Personal Area Networks
3G Offers enhancements to current applications including greater data speeds, increased capacity for voice and data and a broader range of services.
In 2000, ITU approved the following three standards:
• Wireless Sensor Networks • 3G and beyond • 3.9G (LTE), 4G,et al
Coverage (range)
Wireless Key techniques
通信原理 张水英版课件
通信发展概况
2. 近代：
1837年：莫尔斯发明电报系统。 1876年：贝尔发明电话。
5
通信发展概况
3.现代 20世纪60年代以后：
数字通信技术进入高速发展阶段。
近20多年：
数字通信迅猛发展； 光纤通信也携手同行。 两者都成为现代通行网的主要支柱。
6
通信发展概况
塞缪尔·莫尔斯 （Samuel
Finley Breese Morse
44
【例如】
有一个4PSK数字通信系统，现传输 20个码元，其中错了2个码元，那 么误码率为10%；如果每个错误码 元有一个比特错误，那么误比特率 为5%；如果每个错误码元有两个比 特错误，那么误比特率为10%；
45
【例如】
已知某四进制数字传输系统的信息传 输速率为2400（bit/s），接收端在 半小时内共收到216个错误码元，试 计算该系统的误码率。
缺点：
占用频带宽 对同步要求高、系统和设备比较复杂
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1.3 通信系统的分类及通信方式
一、通信系统的分类
按消息的物理特征 按调制方式 按信号特征 按传输媒介 按复用方式
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1、按消息的物理特征
电报通信系统 电话通信系统 数据通信系统 图像通信系统
。 。 。 。
19
2、按调制方式分类
基带传输：将未经调制的信号直接传送，
第1章
绪论
内容
1.1 通信的基本概念 1.2 通信系统的模型 1.3 通信系统分类及通信方式 1.4 信息的度量 1.5 通信系统的主要性能指标
2
1.1 通信的基本概念
消息、信息和信号 通信 通信发展概况
3
通信发展概况
1. 古代：
通信原理(英文版)
can be generalized to power signal.
10
Energy spectral density
Let the energy of an energy signal s(t) be E, then the energy
of
the
signal
is
decided
byE
s2 (t)dt
is
S() s(t)e jt dt
The inverse Fourier transform of S() is the original signal:
s(t) S ()e jtd
【Example 2.3】Find the frequency spectral density of a rectangular pulse.
0, 当t 0,
u(t)
1,
当t 0
1
u(t) = d(t)
0
Fig. 2.2.6 Unit step function
t
➢ Difference between frequency spectral density S(f) of
energy signal and frequency spectrum of periodic power
Chapter 2 Signals
2.1 Classification of Signals
2.1.1 Deterministic signals and random signals
➢ What is deterministic signal? ➢ What is random signal?
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1.3.2 Advantages of Digital Communication
1.2 Message, information & signal
Message：speech, letters, figures, images…
Information：effective content of message. Different types of messages may contain the same information
Finite number of possible values of signals Correct decision may be achieved
(a) Waveforms of distored digital signal
(b) Waveforms of digital signal after shaping
Signal：the carrier of message
What transmitted in a communication system is signal.
Measurement of information：
# “quantity of message” information content
1.3 Digital Communication
1.3.1 Basic concept
Two categories of signals • Analog signal：Its voltage or current
can be expressed by a continuous function of time. For example, speech signal.
# For an equal probability binary symbol:
I = log2 [1/P(x)] =log2 [1/(1/2)] = 1 bit
# For an equal probability M-ary symbol:
I = log2 [1/P(x)] = log2 [1/(1/M)] = log2 M bit If M = 2k ，then I = k bit
Out put S/N increases with bandwidth according to exponential law.
Digital communication system model
Receiver
Source decoding
s(t)
s(t)
t
t
Analog signals
s(t) s(t)
Symbol
t
t
Digital signals
Two kinds of communication systems
• Analog communication system Requirement － High fidelity Criterion － Signal to noise ratio Basic issue － parameter estimation
# Ex: “Rainfall will be 1 mm tomorrow” – information content small
“Rainfall will be 1 m tomorrow” – information content large
“The sun will rise in the east tomorrow morning” – information content equals zero # Information content I = I [ P(x) ]，P(x) – Occurrence probability # Definition：I = loga [1/P(x)] = -logaP(x) # Usually, set a = 2, the unit of the information content will be called a bit.
Digital communication equipment:
➢Design and manufacture are easier ➢Weight & volume are smaller
Digital signal can be compressed by source coding to reduce redundency.
（优选）通信原理英 文版
Chapter 1 Introduction 1.1 Historical Review of Communication
Origin of ancient communication Two modes of communication Development of modern communication
• Digital signal： Its voltage or current can only take finite number of discrete values. For example, digital computer data signal.
Analog Signal & Digital Signal
Fig. 1.3.2 Distortion and restoration of digital signal waveforms
Error correcting techniques can be used.
Digital encryption can be used.
Different kinds of analog & digital message can be integrated to transmit