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
17
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
18
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?
通信原理(数字通信)PCM(41页英文ppt)
A First Course in Digital Communications
Chapter 4: Sampling and Quantization
Sampling Theorem
Theorem A signal having no frequency components above W Hertz is completely described by specifying the values of the signal at periodic time instants that are separated by at most 1/2W seconds. fs ≥ 2W is known as the Nyquist criterion, the sampling rate fs = 2W is called the Nyquist rate and its reciprocal called the Nyquist interval. Ideal sampling is not practical ⇒ Need practical sampling methods.
Sampling: How many samples per second are needed to exactly represent the signal and how to reconstruct the analog message from the samples? Quantization: To represent the sample value by a digital symbol chosen from a finite set. What is the choice of a discrete set of amplitudes to represent the continuous range of possible amplitudes and how to measure the distortion due to quantization? Encoding: Map the quantized signal sample into a string of digital, typically binary, symbols.
通信原理(英文版)
I = log2 [1/P(x)] = log2 [1/(1/2)] = 1 bit
4
# 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.
10
Digital communication system model 11
2
1.2 Message, information & signal
Message:speech, letters, figures, images…
Information:effective content of message. Different types of messages may contain the same information
5
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.
# Ex: “Rainfall will be 1 mm tomorrow” – information content small
通信原理论文(中英文版)
通信原理论文(中英文版)Optimized Pulse Shaping for Intra-channelNonlinearities Mitigation in a 10 Gbaud Dual-Polarization 16-QAM SystemBeno?t Chatelain1, Charles Laperle2, Kim Roberts2, Xian Xu1, Mathieu Chagnon1, Andrzej Borowiec2, Fran?ois Gagnon3, John C. Cartledge4, and David V. Plant11McGill University, Montreal, Quebec, Canada, H3A 2A7 2Ciena Corporation, Ottawa, Ontario, Canada, K2H 8E93école de technologie supérieure, Montreal, Quebec, Canada, H3C 1K34Queen’s University, Kingston, Ontario, Canada, K7L3N6 Email: benoit.chatelain@mail.mcgill.caAbstract: An optimized pulse shape is shown to reduce intra-channel nonlinear effects in a 10 Gbaud dual-polarization 16-QAM EDFA-amplified system without optical dispersion compensation.OCIS codes: (060.2330) Fiber optics communications; (060.4080) Modulation1. IntroductionIntra-channel nonlinear distortion is an important source of signal degradation in opticalcommunication systems using advanced modulation formats such as quadrature amplitude modulation (QAM). Its main impact is to reduce the maximal powerthat can be launched into the fiber, thereby limiting optical signal-to-noise ratio (OSNR) levels at the receiver, reducing system margins and reducing the maximum propagation distance that can be achieved. In this paper, thenonlinear tolerance of an optimized pulse and a root-raised cosine (RRC) pulse is compared in terms of bit error rate (BER) performance, for varying propagation distances and launch powers. Experimental results show that the optimized pulse considerably reduces intra-channel nonlinear effects in a long haul, 10 Gbaud dual-polarization (DP) 16-QAM system relying on erbium-doped fiber amplifiers (EDFAs) and G.652 fiber (no optical dispersion compensation).The improved nonlinear tolerance of the return-to-zero (RZ) pulse shape was recently highlighted in [1], for a 112 Gb/s DP-quadrature phase shift keying (QPSK) system without optical dispersion compensation. Comparing the RZ pulse to the non return-to-zero (NRZ) pulse, the authors reported an increase in single channel maximum propagation distance of 18%. However, the improved nonlinear tolerance achieved using the RZ pulse comes at the expense of increased spectral content. For instance, the bandwidth of a 50% RZ pulse is twice the bandwidth of the NRZ pulse or the RRC pulse with a roll-off factor (α) of 1. The use of a RZ pulse thus reduces spectral efficiency by a factor of two, and for a system using digital signal processing at the transmitter and receiver, at the Nyquist rate, it doubles the required bandwidth and sampling frequency of the digital-to-analog converters (DACs) and analog-to-digital converters (ADCs).(a)(b)Figure 1. Impulse (a) and frequency (b) responses of the RRC and optimized pulses.In comparison to the RRC pulse, the optimized pulse shape presented in [2] was shown to improvethe nonlinear performance of DP-QPSK systems without optical dispersion compensation and to increase the maximum transmission distance by as much as 22%. The specialized pulse was obtained by numerical optimization, with the primary objective formulated to reduce its width, but constrained to have a bandwidth equal to the bandwidth of a NRZ or RRC pulse (α = 1). Therefore,the optimized pulse can be used without penalizing spectral efficiency and without using higher speed DACs and ADCs. Fig. 1 exhibits the time and frequency characteristics of the optimized and RRC pulses. It can be seen that the optimized pulse is narrower than the RRC pulse with α = 1, and that its first-null bandwidth is equal to the baud rate. It is also apparent that the reduced width of the optimized pulse translates in higher energy content for frequencies between 6 GHz and 10 GHz. Through dispersion, the higher energy frequencycomponents produce a propagating pulse and a propagating waveformthat is more broadened, with lower peak power excursions. Since intra-channel nonlinear distortion is proportional to peak power, the optimized pulse makes the system more tolerant to nonlinear effects. In this work and as in [2?5], the RRC pulse is used as the reference pulse for its ability to minimizepulse-induced intersymbol interference (ISI) and to minimize out-of-band power.2. Experimental SetupFig. 2 illustrates the experimental setup. The symbol sources consist of random symbol sequences of length 214 and were followed by pulse shapingfinite impulse response (FIR) filters. DACs with 6-bit resolution drive thein-phase-quadrature (I-Q) modulators associated with the two polarizations. The emitting wavelength was set to 1547.715 nm. A polarization scrambler (PS) was inserted after the polarization beam combiner (PBC) in order to randomly rotate the polarization state. A fiber link consisting of 15 spans of 80 km G.652 fiber was used, together with EDFAs at each span. At the receiver, a noise source was used to adjust the OSNR. The optical spectrum analyzer (OSA) served the purposes of measuring the OSNR. A coherent front-end integrates polarization beam splitters, optical hybrids, a local oscillator and photodetectors [6]. It provides four signals corresponding to the in-phase and quadrature components of the two polarizations. These baseband signals were sampled using a 50 GSa/s oscilloscope with 8-bit ADCs and post-processed in a personal computer. The linewidth of the transmitter and receiver lasers was 100 kHz, and their frequency offset was below 200 MHz. The same clockreference was used for the DACs and ADCs. The receiver signal processingfunctions include matched filtering and chromatic dispersion compensation (CD-1) by FIR filters, polarization recovery by a 13-tap fractionally spaced (T/2) butterfly equalizer (EQ), carrier offset removal and carrier phase recovery by a second order phase lock loop (PLL) and finally, detection. The constant modulus algorithm (CMA) is used for the equalizer coefficients pre-convergence. Once the signal is recovered, the system switches to a decision-directed modulus algorithm (DDMA) [7]. Two symbol pattern periods, totaling 215 symbols for each polarization, were used to produce BER statistics.In what follows, the system performance is studied using either the RRC pulse or the optimized pulse presented in Fig. 1 as transmit FIR filters and receive matched filters.Figure 2. Experimental setup.3. Results and DiscussionFig. 3 displays the electrical eye diagrams of the signal in-phase component taken at the transmitter, after the FIR pulse shaping filter. The inner eye openings of the optimized 16-QAM sequence eye diagram are reduced compare to those in the eye diagram obtained using the RRC pulse, indicating, as mentioned in [2], that the optimized pulse may be more sensitive to timing jitter. Fig. 3 (b) further shows that the eye diagram obtained with the optimized pulse is very similar to the eye diagram that would be obtainedusing an RZ pulse, and that the optimized pulse sequence returns close to azero level between each symbol period. Since the RRC and the optimized pulses are designed to be used as matched filter, it is expected to visualize on the eye diagrams at the transmitter a certain amount of ISI. The RRC and optimized pulses produce a filtered sequence with zero pulse-induced ISI only at the receiver, after matched filtering.Fig. 4 (a) reports the measured BER in a back-to-back configuration for a system using RRC filters and for a system using optimized filters. The linear performance of the RRC and optimized pulses is very similar and for the considered range of OSNR, the minimal and maximal penalty is 2.5 dB and 6.5 dB, respectively. Fig. 4 (b) and (c) show propagation results for 800 km and for 1200 km. At 800 km and considering a BER threshold of 8×10-3, the optimized pulse reduces the OSNR penalty by 0.6 dB and 2.8 dB, for launch powers of �C2 dBm and 0 dBm, respectively. At 1200 km and for a launch power of �C2 dBm an improvement of 1.2 dB is observed. At 1200 km and for a launch power of 0 dBm, the system with optimized pulse shaping almost reaches the BER threshold,while the system using RRC pulses is limited to a BER of 1.8×10-2. At this level, the optimized pulse outperforms the RRC pulse by 4.3 dB. It should be noted that the introduction of soft-decision forward error correction (FEC) [8] would be required to be able to operate at the considered BER threshold.感谢您的阅读,祝您生活愉快。
通信原理-英文版分析
Fig. 1.3.2 Distortion and restoration of digital signal waveforms
9
Error correcting techniques can be used. Digital encryption can be used. Different kinds of analog & digital
Principles of Communications
1
Chapter 1 Introduction 1.1 Historical Review of Communication
Origin of ancient communication Two modes of communication Development of modern communication
5
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. For example, speech signal.
• Digital communication system Requirement - correct decision Criterion - Error probability Basic issur - statistical decision theory
8
1.3.2 Advantages of Digital Communication
Out put S/N increases with bandwidth according to exponential law.
无线通信原理双语讲义第一二讲
⽆线通信原理双语讲义第⼀⼆讲Course Code: B020305Course Title: Wireless Communications Principle and Practice (T. S. Rappaport 2004) Academic Year : 2015 Semester: 2Lecturer: Gao Huanqin (Room1610), College of Commu. and Inform.Engineering,NJUPT Lectures: 32 hours, lectured in English partially.E-mail Address: gaohq@/doc/e24373aa26fff705cc170ad9.html .au前⾔Preface (PP:1)本节课是本课程的第⼀堂课,介绍课程的相关信息;讲授第⼀章教学内容“⽆线通信概述”,它涉及英⽂教科书的第⼀、第⼆章内容。
Content(教学内容)s: Provide fundamental treatment about many practical and theoretical concepts that form the basis of wireless communications, especially fundamental cellular radio concepts such as frequency reuse. Propagation path loss prediction models for cellular networks, multiple access method. ⽆线通信基础相关的基本理论、概念与应⽤,突出基本概念与基础理论,例如蜂窝⽹中频率复⽤。
基础理论例如传播路径损耗预测模型,多址接⼊技术等。
Objective of the course(教学⽬标): After the course the student has a good basic knowledge of cellular and personal communication systems and the systems evolving from it. Also, the student will get a basic knowledge of the design of cellular networks and understand the special requirements, which result from the mobile radio environment. 通过本课程的学习让同学了解⽆线蜂窝通信系统的基本概念、基础理论以及系统演进,了解移动⽆线环境下的蜂窝通信⽹络系统的设计及需求。
通信原理(英文版)课件
Network Security
• Firewalls: Devices that filter incoming and outgoing traffic based on security policies to protect against unauthorized access or malicious attacks.
Modulation and Demodulation
Modulation
The process of varying a property of a carrier wave, such as its amplitude, frequency, or phase, in accordance with the information to be transmitted. This allows information to be carried over long distances through various media.
Channel Capacity and Data Rate
Channel Capacity
The maximum amount of information that can be transmitted over a communication channel without loss of data or degradation in signal quality. It is typically limited by the physical properties of the channel and the noise level present.
通信原理英文版教学课件:class six-2ASK
PA(f) - power spectral density of A(t)
∴If PA(f) has been found, then Ps(f) can be calculated by substituting PA(f) int the above equation.
Therefore the mean power of the output noise of the bandpass filter is:
Hence its output signal to nno2 isen0rBati1o.9i2s: 10 8 W
∴(1)the
r symbol
A2
106
1
1
erf
4
ha
2 n
1
1
erf
4
h
2
n
When h equals the optimum threshold h*,
p1(x*) p0 (x*)
Pe
1 erfc 2
r /2
When r>>1,
Pe
1 er / 4
r
13
Envelope detection
∵ The output is the envelope of its input voltage y(t), we have
∴When 1 is transmitted, the probability of x(t) is
p1(x)
1
2
n
exp
(x
A) 2
计算机英语计算机通信详解演示文稿
Finally, digital technologies create and send electrical impulses that correspond to the series of 1s and 0s. Digital information can be transmitted faster and more clearly than analog signals, because the electrical impulses only need to correspond to two digits and not to the full range of qualities that compose the original message, such as the pitch and volume of a human voice. While digital transmissions can be sent over wires, cables or radio waves, they must be decoded by a digital receiver. New digital telephones and televisions are being developed to make telecommunications more efficient.
计算机英语计算机通信详解演 示文稿
第一页,共35页。
优选计算机英语计算机通信
第二页,共35页。
第七单元:计算机通信
• 课文A:电信与计算机
第三页,共35页。
Telecommunications allows people around the world to contact one another, to access information instantly, and to communicate from remote areas. Telecommunications usually involves a sender of information and one or more recipients linked by a technology, such as a telephone system, that transmits information from one place to another.Telecommunications devices converts different types of information, such as sound and video, into electronic signals. The signals can then be transmitted by means of media such as telephone wires or radio waves.
通信原理英语实验报告
Experiment Title: Basic Principles of Communication SystemsDate: [Insert Date]Objective: The objective of this experiment was to understand the basic principles of communication systems, including the transmission and reception of signals, modulation techniques, and demodulation processes. Through this experiment, we aimed to familiarize ourselves with the theoretical concepts and practical applications of various communication methods.Materials and Equipment:- Communication System Trainer- Signal Generator- oscilloscope- Function Generator- Power Supply- Communication channel simulator- Modulator and Demodulator UnitsExperiment Procedure:1. Signal Generation and Transmission:- The experiment began with generating a sinusoidal signal using the signal generator. This signal served as the input for the communication system.- The generated signal was then passed through the communication channel simulator, which simulated the effects of a real-world communication channel, such as noise and attenuation.- The output of the channel simulator was observed using the oscilloscope to ensure that the signal had undergone the desired transmission process.2. Modulation Techniques:- To enhance the signal's ability to carry information over a long distance and reduce the impact of noise, modulation techniques were applied.- Amplitude Modulation (AM) was performed by adjusting the amplitude of the carrier signal in accordance with the message signal.- Frequency Modulation (FM) was also demonstrated by varying the frequency of the carrier signal based on the message signal.- The modulated signals were then observed on the oscilloscope to analyze the effects of modulation on the signal.3. Demodulation Process:- After modulation, the next step was to demodulate the received signal to retrieve the original message signal.- For AM, the process involved extracting the amplitude information from the modulated signal using a demodulator.- Similarly, for FM, the demodulator extracted the frequency information to reconstruct the message signal.- The demodulated signals were compared with the original signal to evaluate the effectiveness of the demodulation process.4. Error Detection and Correction:- To ensure the integrity of the transmitted information, error detection and correction techniques were implemented.- A simple parity check was used to detect errors in the received signal.- In case of errors, the receiver requested the retransmission of the data to ensure accuracy.Results and Discussion:1. Signal Transmission:- The transmission of the signal through the communication channel simulator was successful, and the output signal was observed on the oscilloscope.- The presence of noise and attenuation in the channel was evident from the distorted waveform.2. Modulation Techniques:- The modulation techniques were successfully applied to the input signal, and the modulated signals were observed on the oscilloscope.- AM and FM techniques were effective in enhancing the signal's ability to carry information over a long distance.3. Demodulation Process:- The demodulation process was successful, and the demodulated signals were compared with the original signal to ensure accuracy.- The AM and FM demodulated signals were in close agreement with the original signal, indicating a successful demodulation process.4. Error Detection and Correction:- The parity check method was effective in detecting errors in the received signal.- The error detection mechanism ensured that the transmitted information was accurate and reliable.Conclusion:This experiment provided a comprehensive understanding of the basic principles of communication systems. The successful transmission, modulation, demodulation, and error detection and correction processes demonstrated the effectiveness of various communication techniques. Through this experiment, we gained practical experience in implementing and analyzing communication systems, which will be beneficial in our future studies and applications in the field of telecommunications.References:- [Insert relevant references to textbooks, articles, or online resources used during the experiment.]Appendix:- [Insert any additional data, graphs, or tables that support the findings of the experiment.]。
- 1、下载文档前请自行甄别文档内容的完整性,平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益,请联系客服反馈,我们会尽快为您处理(人工客服工作时间:9:00-18:30)。
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