通信和电子信息科技英语总省公共课一等奖全国赛课获奖课件.pptx

Exercises.Please translate the following words and phrases into Chinese.1.sample function2.ensemble average 3.physical significance4.a Fourier transform pair5.deterministic waveform6.in the limit 7.time invariant8.an upperfrequency limit9.Parsevals theorem 10.random pulses样本函数总体均值物理意义傅立叶变换对确定性波型在极限情况下时不变频率上限巴塞瓦尔定理随机脉冲第1页Exercises.Please translate the following words and phrases into English.1.随机过程2.统计平均3.随机变量4.自相关函数5.傅里叶变换6.功率谱密度7.概率密度函数8.高斯过程9.平稳过程10.统计独立random process statistical average random variable autocorrelation function Fourier transform power spectral density probability density function gaussian process a stationary process statistically independent 第2页11.时间平均(值)12.统计特征13.各态历经过程14.狄拉克函数time average statistical characteristic ergodic process delta function 第3页Exercises.Fill in the blanks with the missing word(s).1.The ensemble averages will be identical the statistical averages and may be represented by the same symbols.2.The averages determined by measurements a single sample Function successive times will yield a time average,which we represent as n2(t1).3.Suppose,for example,that the statistical characteristics of the sample Functions the ensemble were changing with time.4.For it may happen that while each sample function is stationary the individual sample functions may differ statistically one another.5.As an extension of that result we shall define the power spectral density of a random process the same way.withonatinfromin第4页Exercises6.It is interest to inquire whether G(f)defined Eq.(1.2)for a random process has a physical significance whichcorresponds to the physical significance of G(f)for deterministic waveforms.8.Hence,if we should select some sample function,a knowledge of the value of n(t)at time t would be no assistance improving our ability to predict the value attained by that same sample function at time t+.9.Hence,whenever we make an observation or measurement of the pulse waveform which extends a duration long enough so that the average observed pulse shape,such as their amplitudes,widths,and spacings are representative of the waveform generally,we shall find that Eq.(1.12)applies.ofinofinover第5页Exercises10.Let us select a section of this waveform which extends -T/2 -T/2.11.Since we have assumed an ergodic process,we are at liberty to (perform,performing)the averaging any sample function of the ensemble,since every sample function will yield the same result.tofromperformover第6页.Please translate the following words and phrases into Chinese.1.physical syste2.rise time 3.amount of information 4.in principle 5.gaussian channel 6.probability density 7.rootmeansquare 8.trade off 9.lower bound 1.equalizer 11.vice versa 12.upper limit Exercises物理系统，实际系统物理系统，实际系统上升时间上升时间信息量信息量理论上，标准上理论上，标准上高斯信道高斯信道概率密度概率密度均方根值均方根值,均方根；均方根均方根；均方根()交替换位，折衷选择交替换位，折衷选择下界下界,下限下限均衡器均衡器反之亦然反之亦然上限上限第7页.Please translate the following words and phrases into English.1.通信理论2.香农定理3.信道带宽4.信号波形5.理想低通滤波器 6.自相关函数7.无噪声高斯信道 8.通信信道9.信息速率10.信噪比Exercisescommunication theory(theory of communications)Shannons theoremchannel bandwidthsignal waveformideal lowpass filterautocorrelation functionnoiseless gaussian channelcommunication channelinformation rateSignal to noise ratio（SNR,S/N）第8页Exercises11.信道容量12.双边功率谱密度13.误码率14.奈奎斯特采样速率15.限带高斯信道16.高斯白噪声channel capacityTwo sided power spectral densityerror probability(probability of error)Nyquist sampling rateband limited gaussian channelwhite Gaussian noise第9页Exercises.Fill in the blanks with the missing word(s).1.There is a negative statement associated Shannons theorem.2.the purpose of transmission over the channel,the messages are represented by fixed voltage levels.3.Since the transmission of any of the M messages is equally likely,H=log2M,thus our channel is transferring information a rate R=rH.4.For a fixed signal power and the presence of white gaussian noise the channel capacity approaches an upper limit with increasing bandwidth.5.It is great interest to recognize that the tradeoff between bandwidth and signal to noise ratio is not limited by a lower limit bandwidth.withonatinofin第10页Exercises6.The signal is transmitted a channel which can be represented as a lowpass RC circuit with cutoff at 1 Hz.7.If there is no noise,then we are entirely free to make for the attenuation by the use of an amplifier and to correct the frequency distortion by the use of an equalizer.8.That is,we need to estimate the interval T which should be assigned to each message to allow the transmitted levels to be recognized Individually the receiver,even though the bandwidth B of the channel is limited.9.Therefore,the 25 percent reduction bandwidth requires a 60 percent increase signal power.inasinofover第11页Exercises10.While we have used the term communication channel many occasions,it is well to emphasize at this point,that the term,which is Something an abstraction,is intended to encompass all the features and componentparts of the transmission system which introduce noise or limit the bandwidth.11.The probability of error is close unity for every possible set of M transmitter signals.12.It turns out the results obtained for a gaussian channel often provide a lower bound the performance of a system Operating a nongaussian channel.inthatintoinas第12页.Please translate the following words and phrases into Chinese.1.overall performance 2.crest factor 3.nonlinear operation 4.inverse operation5.rms 6.PAM 7.PDM 8.PPM 9.maximum magnitude 10.error intervals11.Entropy12.round off13.quantum level 14.DPCMExercises总性能总性能振幅振幅(波峰波峰)因数因数(振幅与有效值之比振幅与有效值之比)非线性运算非线性运算逆操作逆操作均方根均方根(值值)脉幅调制脉幅调制(pulse amplitude modulation)脉宽调制脉宽调制(pulse duration modulation)脉脉(冲相冲相)位调制位调制(pulse phase modulation)最大幅值最大幅值误差间隔误差间隔熵熵,平均信息量平均信息量舍入，用四舍五入化为整数舍入，用四舍五入化为整数量化电平量化电平差分脉冲编码调制差分脉冲编码调制(differential pulse code modulation)第13页Exercises.Please translate the following words and phrases into English.1.正脉冲2.脉冲编码调制3.解码器4.编码器5.量化步长6.峰值7.线性函数8.脉冲序列9.均匀量化器10.预测编码11.压扩器12.压缩比 positive pulsepulse code modulation(PCM)decoderencoderquantum step sizepeak magnitudeslinear functionpulse trainuniform quantizerpredictive codingCompandorcompression ratio第14页Exercises.Fill in the blanks with the missing word(s).1.PCM is a widely different form of modulation compared with the analog pulse types such PAM,PDM,and PPM.2.The characteristics of the pulse group are related the message sample through operations called quantization and coding.3.The term symbol coder distingnishes this coding operation the overall source encoding process.In most cases,a variablelength code is used to represent the mapped and quantized data set.It assigns the shortest codewords the most frequently (occurring,occure,occurred)output values and thus reduces coding redundancy.4.Thus,a quantization error exists PCM and,as will be seen,is the Basic limitation in performance.5.Quantization and sampling produce the same result sampling and quantizing.astofromtooccuringinas第15页Exercises6.For equal peak magnitudes,signals with large crest factors give poorer performance those with small Kcr.7.In the receiver the inverse operation is implemented an expandor restore the original message.8.The digital data is fed serially the decoder.9.the rate drops,samples are made less frequently and step sizes increase.10.The actual compression ratio resulting this method is no more than an order of 41.11.In an attempt to （reduce，reducing）the number of codes sent by a PCM system,a slight variance sampling method is used by a system known Differential Pulse Code Modulation(DPCM).thanbytointoasfromreduceonas第16页Exercises.Please translate the following words and phrases into Chinese.1.channel coding2.transmission bandwidth3.Single sided noise power density4.orthogonal signaling 5.FEC6.logic table7.systematic code8.AWGN 信道编码信道编码传输带宽传输带宽单边带噪声功率密度单边带噪声功率密度正交信号正交信号前向纠（前向纠（forwarderrorcorrection)逻辑表逻辑表系统码系统码加性高斯白噪声加性高斯白噪声(additive white Gaussian noise)第17页Exercises9.BER10.trellis diagram 11.constraint length12.vector array 13.algebraic function 14.state diagram15.cyclic shift16.generator matrix误码率误码率,误比特率误比特率(Bit Error Ratio)网格图网格图 制约长度制约长度向量数组向量数组(矩阵矩阵)代数函数代数函数状态图状态图循环移位循环移位生成矩阵生成矩阵第18页Exercises.Please translate the following words and phrases into English.1.检错码 2.信道容量 3.分组码 4.卷积码 5.移位存放器 6.汉明距离 7.码重 8.树形图9.编码增益error detection codeschannel capacityblock codesconvolutional codesshift registerHamming distancecode weight(weight of a code)tree diagramcoding gain第19页Exercises10.平均比特能量11.码距12.纠错码13.带宽效率14.模2加法器15.原始数据16.编码率17.生成多项式18.循环码 average bit energycode distance(distance of a code)error correction codesbandwidth efficiencymodulo 2 adderraw datacode rategenerator polynomialcyclic codes第20页Exercises.Fill in the blanks with the missing word(s).1.Channel coding protects digital data errors by selectively introducing redundancies in the transmitted data.2.By proper encoding of the information,errors induced a noisy channel can be reduced any desired level without sacrificing the rate of information transfer.3.Error control coding waveforms,the other hand,have bandwidth expansion factors that grow only linearly the code block length.4.In a block encoder,k information bits are encoded ncode bits.frombytoonwithinto第21页Exercises5.The block code is referred to an(n,k)code,and the rate of the code is defined Rc=k/nand is equal the rate of information divided by the raw channel rate.6.Convolutional codes are fundamentally different block codes in that information sequences are not grouped distinct blocks and encoded.7.The tree diagram shows the structure of the encoder the form of a tree with the branches （represent，represented，representing）the various states and the outputs of the coder.8.This reduces the bandwidth efficiency of the link high SNR conditions,but provides excellent BER performance low SNR values.9.A systematic code is one which the parity bits are appended the end of the information bits.10.A channel coder operates digital message(or source)data by encoding the source information a code sequence for transmission the channel.astoasfromintoinrepresentinginatintoonintothrough第22页Exercises.Please translate the following words and phrases into Chinese.1.AM2.DPSK3.PAM4.PDM5.PPM6.PCM7.DPCM8.ASK9.FSK10.FDM11.TDM12.coded modulation13.suppressed carrier14.modulated signal幅度调制幅度调制(amplitude modulation)差分相位键控差分相位键控(Differential PSK)脉脉(冲振）幅调制冲振）幅调制(pulse amplitude modulation)脉宽调制脉宽调制(pulse duration modulation)脉（冲相）位调制脉（冲相）位调制(pulse phase modulation)脉脉(冲编冲编)码调制码调制(pulse code modulation)差分脉冲编码调制差分脉冲编码调制(differential pulse code modulation)振振幅键控幅键控(amplitudeshift keying)移频键控移频键控(frequencyshift keying)频分（多路）复用频分（多路）复用(frequencydivision multiplexing)时分（多路）复用时分（多路）复用(timedivision multiplexing)编码调制编码调制抑制载波抑制载波已调信号已调信号第23页Exercises.Please translate the following words and phrases into English.1.带通信号2.脉冲调制3.角度调制4.残留边带抑制载波调制5.绝对带宽6.脉冲宽度7.线性函数8.载波频率9.模拟调制10.移相键控11.连续波调制12.同轴电缆bandpass signalpulse modulationangle modulationVestigial sideband suppressed carrier modulationabsolute bandwidthpulse durationlinear functioncarrier frequencyanalog modulationPSK(phase shift keying)continuous wave(cw)modulationcoaxial cable第24页Exercises.Fill in the blanks with the missing word(s).1.The method involves first sampling the information signal,quantizing the sample by rounding off to the closest of a number of discrete levels,and finally generating a prescribed number of pulses according to a code related to the nearest discrete level.2.Coded modulation will also be referred to as digital modulation.It is one of the most modern and useful methods of modulation available today.3.In PPM pulse position is proportional to the amplitude of the message signal4.Timedivision multiplexing(TDM)uses pulse modulation to put samples of different signals in nonoverlapping time slots.For instance,the gaps between pulses could be filled with samples from other signals.5.It is often necessary to use modulation to translate the useful band of frequencies up to a large carrier frequency so that efficient electromagnetic radiation is possible from an antenna having reasonable size.第25页Exercises6.The design of a communication system may be constrained by the cost and availability of hardware,whose performance often depends on the frequencies involved7.Fractional bandwidth considerations account for the fact that modulationunits are found in receivers as well as in transmitters.8.These methods may be characterized as continuous wave(cw)modulation.9.Since each station has a different assigned carrier frequency,the desired signal can be separated from the others by filtering.10.PCM may be either binary,where pulses have only two voltage levels,or -ary,where pulses may take on possible levels.11.By exploiting the frequency translation property of cw modulation,message information can be impressed on a carrier whose frequency has been selected for the desired transmission method.第26页Exercises.Please translate the following words and phrases into Chinese.1.copper wire2.speech recognition3.adaptive differential PCM 4.infinite impulse response(IIR)5.realtime conversation6.digital signal processing 7.CELP8.VAD9.MPE10.ADPCM11.direct quantization12.log pulse PCM quantizer铜线铜线语音识别语音识别自适应差分脉码调制自适应差分脉码调制无限脉冲响应无限脉冲响应实时交谈实时交谈数字信号处理数字信号处理码激励线性预测（码激励线性预测（code excited linear prediction)话音激活检测器话音激活检测器(voice activity detector)多脉冲激励多脉冲激励(multipulse excitation)自适应差分脉码调制自适应差分脉码调制(adaptive differential PCM)直接量化直接量化对数脉冲对数脉冲PCM量化器量化器第27页Exercises.Please translate the following words and phrases into English.1.共振峰跟踪滤波器 2.国际电信联盟 3.背景噪声 4.双向通信 5.基音跟踪滤波器 6.长时预测7.语音编码8.声码器9.语音增强10.波形跟随编码器11.参数编码器12.频域编码器铜线铜线语音识别语音识别自适应差分脉码调制自适应差分脉码调制无限脉冲响应无限脉冲响应实时交谈实时交谈数字信号处理数字信号处理码激励线性预测（码激励线性预测（code excited linear prediction)话音激活检测器话音激活检测器(voice activity detector)多脉冲激励多脉冲激励(multipulse excitation)自适应差分脉码调制自适应差分脉码调制(adaptive differential PCM)直接量化直接量化对数脉冲对数脉冲PCM量化器量化器第28页Exercises.Fill in the blanks with the missing word(s).1.Speech coding is a fundamental technology that has existed for more than 60 years,beginning in the 1930s with Dudleys original vocoder.2.Speech coding is distinct from the more general problem of audio coding in that the primary signal of interest is the speech itself.3.Virtually all existing telecommunications applications begin with speech coded by this standard.4.The selection of appropriate excitation pulses is carried out in a perceptually weighted domain,ratherthan just minimizing the mse in the waveform domain so that the quantization noise is less audible to the listener.5.Signal delay is a measure of the duration of the speech signal used to estimate coder parameters reliably for both the encoder and the decoder,plus any delay inherent in the transmission channel.第29页Exercises6.If the round trip delay is held(holds,is held,held)below 300 ms and there is sufficient echo cancellation,the quality is quite acceptable.7.If the number of bits provided by the coder over time is always the same,the rate is fixed.8.Voice activity detectors(VAD)that attempt to determine whether speech is actually present so