通信工程专业英语习题.doc

第一课1. 将下述句子译成英文。(1) An analog information source produces messages that are defined on a continuum, while a digital information source produces a finite set of possible messages.(2) The beacon-fire tower in ancient China was a communications system.(3) Show that the entropy is a maximum when the probability of sending a binary 1 is equal to the probability of sending a binary 0 .(4) Information capacity is a measure of how much information can be transferred through a communications system in a given period of time .(5) The wider the bandwidth and the longer the time of transmission, the more information can be conveyed through the system .2. Answer the following questions :(1) Samuel Morse developed the first electronic communications system in 1837 .(2) Yes.(3) The vacuum-tube triode .(4) Hartleys law simply states that the wider the bandwidth and the longer the transmission time, the more information that can be conveyed through the system . The Shannons formula is I=Blog2(1+S/N) , where I=information capacity(bps), B=bandwidth(Hz), S/N=signal-to-noise power ratio(unitless) .(5) (a) VLF, (b) MF, (c) SHF第二章 信息源1. 根据课文回答下列问题。(1) There are four important information sources: speech, music, pictures, and computer data.(2) Three successive stages: production, propagation, and perception.(3) The bandwidth of 300 to 3100Hz.(4) A musical signal differs from a speech signal in that its spectrum occupies a much wider band of frequencies that may extend up to about 15kHz.(5) The dynamic pictures, as in television, are in motion; while the static pictures, as in facsimile, are still.(6) In black-white TV, only a luminance signal is needed. However, in color TV, there are three signals: a luminance signal and a pair of chrominance signals.(7) Yes.(8) Suppose the seven data bits are 0110101. For the odd parity, an extra parity bit of 1 should be ended, so that the total number of 1s is 5, which is odd. (9) Lossless compression operates by removing the redundant information contained in the data of interest. Lossy compression involves the loss of information in a controlled manner. Lossy compression may achieve a compression ratio higher than that attainable with lossless methods.(10) There are four distinct operations: time-frequency mapping, psychoacoustic modeling, quantization and coding, and frame-packing.2. 翻译下列词汇。 synchronous transmission asynchronous transmission mutiplexer frame frame-packing modeling3. 用英文描述摄像机的扫描过程。 The type of scanning used in TV camera is a form of spatial sampling called raster scanning, which converts a two-dimensional image intensity into a one-dimensional waveform; it is somewhat analogous to the manner in which we read a printed paper in that the scanning is performed from left to right on a line-by-line basis.第三章 信号与噪声1. 请将下列词组译成英文。 mathematic model rms value orthogonal series power density spectrum instantaneous power common logarithm(the base 10 logarithm) block diagram signal-to-noise ratio DC power supply AC ripple AM receiver thermal noise2. 请写出下列缩写词的原文。 root-mean-square alternating current direct current decibel radio frequency cable(common antenna) television Fourier series amplitude modulation frequency modulation phase modulation bipolar junction transistor field-effect transistor第四章 信号的产生1. 将下列词汇译成英文。 inductive coil capacitor impedance reactance susceptance radio frequency oscillator flywheel effect rating powerpiezoelectric crystal quality factor2. 根据课文回答下列问题。(1) The Q factor of a component is the ratio of the energy stored to that which is lost in the component .(2) The component dissipation is the reciprocal of its Q factor .(3) Resonance can be defined as a circuit condition whereby the inductive and capacitive reactance have been balanced .(4) The bandwidth of a filter is the frequency range from its low-cutoff to high-cutoff frequency .(5) A bandpass filter can be built by using the circuit shown in Fig.4-3(a) . If the output voltage eout is across the series of capacitor C and resistor R2 , then it is a lowpass filter .3. 用英文描述RLC电路中的飞轮效应。 Suppose a charged capacitor is connected to an inductor and a resistor in series. Once the circuit is closed, a current starts as the capacitor begins to discharge through the inductor. The inductor, which resists a change in current flow, cause a gradual sinusoidal current buildup that reaches maximum when the capacitor is fully discharged. At this point the potential energy is zero, but since current is maximum, the magnetic field energy around the inductor is maximum. The magnetic field no longer maintained by capacitor voltage then starts to collapse, and its counter EMF will keep current flowing in same direction, thus charging the capacitor to the opposite polarity of its original charge. This repetitive exchange of energy is known as the flywheel effect. 第五章 随机过程ensemble average (mean) time average correlation function autocovariance the first-order moment power spectral densitysample space random variable wide-sense stationary processunbiased estimation normalized linear functional1. 将下列句子译成英文。(1) The time average of a stationary process may be used to estimate its ensemble average.(2) The noise at the front of a receiver is greatly significant to a communications system.(3) The autocorrelation function of a random process has some important properties.(4) Many phenomena can be described as a Gaussian process, therefore, the Gaussian process is termed as the normal process.(5) The mathematic expectation of a random process is its first-order moment related to the original point.2. 用英文回答下列问题。(1) If a process is divided into a number of time intervals, the various sections of a stationary process exhibit essentially the same statistic properties.(2) If the statistic properties of a process can be estimate by its time behavior, it is ergodic.(3) Each outcome of a random experiment is associated with a sample point. The totality of sample points corresponding to the aggregate of all possible outcomes of the experiment is called the sample space.(4) If the first- and second-order distribution function of a random process are independent of time, it is weakly stationary; while if its arbitrary order distribution is independent of time, it is strictly stationary.(5) Because a random process is not just a time function, it is a random variable also.笫六章 调幅发射1. 2. 翻译下列词汇。modulating signal modulated wave emitter modulator DSB AMtransistorized transmission unitless lo-level modulator DC power suply3. 0.15 V。4. LSF=1MHz-1kHz, USF=1MHz+1kHz 。999kHz 1001kHz 。 Unchanged .5. 根据课文回答下列问题。(1) Modulation is defined as the process of impressing low-frequency information signals onto a high-frequency carrier signal. May be more than ten types of modulation have been heard, such as AM, FM, PM, QAM, FSK, PSK, and so on.(2) Two inputs and one output.(3) No.(4) The location in a transmitter where modulation occurs determines whether the circuit is a low- or high-level transmitter.(5) This is accomplished by placing several final power amplifiers in parallel such that their output signals combine in phase. In addition, to achieve high power efficiency, medium- and high-power AM modulator generally operate class C.第七章 单边带调制23. Translate the following sentences into English.(1) The amount of frequency shift is equal to the absolute value of the difference between the frequencies of the quadrature oscillators(2)This type of distortion caused by frequency error in the demodulation process is unique to SSB modulation system.(3)Any error in the frequency or the phase of the local oscillator signal in the receiver, with respect to the carrier wave, gives rise to distortion in the demodulated signal.(4)In order to reduce the effect of frequency error distortion in telephone systems, we have to limit the frequency error to 2-5 Hz(5)A phase-lock-loop (PLL) circuit can be implemented that will give a higher frequency quadrature oscillator 第八章 角度调制1 Fill in the blanks with proper words, phrases and clauses.(1) When thermal noise with a constant spectral density, FM, deviation, carrier frequency, relative amplitude of the noise, demodulated, frequency component, The spectral shape of the demodulated noise depend on, whereas the noise voltage at the output of an FM demodulator increases linearly with frequency, commonly called.(2) In essence, frequency and phase modulators, modulating signal, the carrier oscillator, indirect, When the phase of the carrier signal is modulated by the information signal, direct PM (indirect FM) result. 2Translate the following passages into Chinese or English.(1) With the use of limiters, FM and PM demodulators can actually reduce the noise level and improve the signal-to-noise ratio during the demodulation process.(2) High-quality angle modulation produces many side frequencies, thus necessitating a much wider bandwidth than is necessary for AM transmission.。(3) Whenever the period (T) of a sinusoidal carrier changes, its frequency and phase also change, and if the changes are continuous, the wave is no longer a single frequency.第九章 传输线1 Fill in the blanks with proper words, phrases and clauses.(1) radiation losses and interference, a conductive metal braid, connected to ground and acts as a shield, electromagnetic interference, A shielded-parallel wire pair consists of two parallel wire conductors separated by a solid dielectric material, enclosed, a protective plastic coating(2) balanced mode, potential, coaxial cable, prevent static interference from penetrating the center conductors. 2 Translate the following passages into Chinese or English.(1) The characteristics of a transmission line are determined by its electrical properties, such as wire conductivity and insulator dielectric constant, and its physical properties, such as wire diameter and conductor spacing.(2) Because current flows through a transmission line and the transmission line has a finite resistance, there is an inherent and avoidable power loss.第十章 电磁波传播 2Fill in the blanks with proper words, phrases and clauses.3. Translate the following sentence into English(1)The velocity at which an electromagnetic wave propagates is inversely proportional to the density of the medium in which it is propagating.(2) Refraction occurs whenever a radio wave passes from one medium into another medium of different density.(3)When the reflecting surface is not plane (i.e., it is curved), the curvature of the reflected wave is different from that of the incident wave.(4)As an electromagnetic wave propagates through Earths atmosphere, energy is transferred from the wave to the atoms and molecules of the atmosphere.(5)Absorption of radio frequencies in a normal atmosphere depends on frequency and is relatively insignificant below approximately 10 GHz.第十一章 天线和波导2. Fi