电子信息与通信工程专业英语期末必考翻译复习课程

电子信息与通信工程专业英语期末必考翻

译

1. "I n most cases, these

sig nals origi nate as sen sory data from the real world: seismic vibrati ons visual images, sound waves, etc. DSP isthe mathematics, the algorithms, and the tech niq ues used to man ipulate these sig nals after they have bee n con verted into a digital form." 在大多数情况下，这

些信号来源于人对真实世界的感觉，比如地震的震动，视觉图像，声音波形等。数字信号处理是一种数学工具，是一种用来处理那些将上述信号转换成数字形式后的信号的算法和技术。

2. Fourier ' s representation of function sas a superpositi on of sines and cos ines has become Ubiquitous for both the

an alytic and nu merical solutio n of differe ntial equatio ns and for the an alysis and treatme nt of com muni cati on sig nals 函数的傅里叶表示，

即将函数表示成正弦和余弦信号的叠加，这种方法已经广泛用于微分方程的解析法和数值法求解过程以及通信信号的分析和处理。

3.lf f (t ) is a non periodic sig nal, the summatio n of the periodic fun cti ons ,such as sine and cos ine, does not accurately represe nt the sig nal. You could artificially exte nd the sig

nal to make it periodic but it would

require additi onal con ti nu ity at the

end points . 如果f(t) 是

非周期信号，那么用周期函数例如正弦

和余弦的和，并不能精确的表示该信号

f(t)。你可以人为的拓展这个信号使其

具有周期性，但是这要求在端点处附加

连续性

4. A digital filter is a mathematical

algorithm impleme nted in hardware,

firmware, and software that operates

on a digital in put sig nal to produce a

digital output sig nal for achiev ing

filteri ng objectives. 数字滤

波器是一种数学算法，它可以用硬件，

固件和软件来实现。它作用于数字输入

信号产生数字输出信号从而达到滤波目

标。

5. The basic idea of Fourier series

method is to desig n an

FIR filter that approximates the

desired freque ncy resp onse of filter

by calculating its impulse resp on

se." 用傅里叶级

数设计FIR滤波器的基本的理念是计

算出此滤波器的单位冲激响应来逼近所

期望的滤波器的频率响应。

II

6. "If the sig nal has sharp tran siti on

s, it is n ecessary to win dow the

in put data, so that the secti ons conv

erge to zero at the en dpoi nts" 如果

信号有急

剧的过渡，就有必有对输入信号加窗，

这样信号在端点处就会收敛于零。

7. " The concepts of signal s and

systems arise in a

wide

variety of fields, and the ideas and

techniques asso

ciated

with these con cepts play a

n importa nt role in such diverse

areas of scienee and techn ology as

com muni cati on,

aeron autics and astr on auti cs,

circuit desig n, acousti cs,

seismology, biomedical eng in eeri

ng, en ergy gen erati on

distributi on systems, chemic al

process con trol, and sp

eech

process ing. " 信号与系统的

概念出现在广阔的范围内，在科学技术

的不同领域，如通信、航空航天、电路

设计、声学、地震学、生物学、生物医

学工程、发电和输电系统、化学过程控

制和语音处理中都离不开这个概念的思

想与技术。它在科学技术中发挥了重要

作用。

8. " Without some restrictio ns, when

the

characterizati on of a syste

m requires a complete inpu

t-out-

put relatio nship, knowing t

he output of a system to a certa in

set of in put doe not allow us to deter

mine the output of the sy

stem to other sets of inp

uts."当系统的特性描述要求完整的输

入输出关系时，如果没有约束

条件，即使知道了系统对某些特定输

入产生的输出时，我们也并不知道系统

对其他输入产生的输出。

9.A n example of a fin ite-

en ergy sig nal is a sig nal

that takes on the value

1 for 0< t <

1 and 0 otherwise. 举一个

有限能量信号的例子：信号在0W t <

1,而在其他时间范围取值为0。

10. This, of course, makes

sen se, since if there is

a non zero average en ergy p er unit

time, the n in tegra ting or summing

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间隔范围内，对其积分或 者求和就会产生一个无限的能量总 和。

11. We can bring continuous time and discretetime systems together throu gh the con cept of sampli ng

, and we can develop some in sights into the use of discrete

time systems to process co n ti nu ous-

time sig nals that have bee n sampled.我们可以在抽样的概 念下

将连续时间和离散时间系统放 在一起考虑。我们可以将一些离散 时间系统的概念推广，用以处理抽 样后的连续时间系统。

12.O ne of th e most importa nt motivati ons for the dev elopme nt of general tools for an alyz ing and desig ning systems is that

systems from many differe nt applicati ons have very si

milar

13.Electro nic amplifiers are ofte n symbolized by a simple triangle shape ,where the in ternal comp onents are not in dividually represe nted. 电子放大器一般都表示成三 角形形状，内部器件并不分别表示 出来。 14..A n in creas in gly positive

voltage on the(+)i nput tends to drive

the output voltage more positive,a nd an in creas in gly positive voltage on the(-)i nput tends to drive the output voltage more negative. 增大同向输入端的电 压，会使输出电压增大；增大反向 输入端的电压，会使输出电压减

小。

15.Because we know that both in

puts of the op-amp have extremely

high impeda nce,we can safely

assume they won't add or subtract any curre nt through the divider. 因

为我

们知道，运算放大器的两个输入端 之间有无穷大的电阻，所以我们完 全可以假句话 说，我们可以认为R1和R2串联， 即通过R1的电流一定会通过R2。 17. FPGAs,which do not use operati ng sytems,mi ni mize

reliability cincerns with true parallel

executi on and determi nistic

hardware dedicated to every task. FPGA 不使用操作系统，减 少了对每项任务并行操作和确定的 硬件分配的依赖性。

18. Digital com muni cati on protocols,for example,have

specifications that can chang over

time,a nd ASIC-based in terfaces may cause maintenance and forward compatibility challe nges. 例如，数字通信协议规范可 能

随时改变，基于ASIC 的接口则 保持稳定且兼容。

19. VHDL is an acro nym for Very

high speed in tergrated

circuit(VHSIC)Hardware Descriptio n

描述语言的缩写，它是一种通过 函数、数据流和(或)结构描述逻 辑电路的可编程语言。

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for both the an alytic and nu merical solutio n of differe ntial equatio ns and for the an alysis and treatme nt of com muni cati on sig nals.

函数的傅里叶表示，即将函数表 示成正弦和余弦信号的叠加，这种方 法已经广泛用于微分方程的解析法和 数值法求解过程以及通信信号的分析 和处理。 The Fourier transform ' s utility

lies in its ability to analyze a sig nal in the time doma in for

its freque ncy content. The tran sform works

by first tran slati ng a function in the time doma in

in to

a function in the

freque ncy

doma in.

The

sig nal can the n be an alyzed for its freque ncy content because

the

Fourier

傅里叶变换的效用在于它能够在 时域范围内分析它的频率内容。变换 的第一步是将时域上的函数转换为时 域表示。然后就可以分析信号的频率 内容了。因为变换函数的傅里叶系数 代表各个正弦和余弦函数在各自对应 频率区间的分配。傅里叶逆变换就会 按你刚才设想的那样，将频域数据转 换为时域的。

The discrete Fourier tran sform (DFT) estimates the Fourier tran sform of a fun cti on from a finite number of its sampled points. The sampled points are supposed to be typical of

what the signal looks

like at all other times

离散型傅里叶变换是通过他有限 的采样点来评估函数的傅里叶变换。 采样点代表了其他时间的信号。

The DFT has symmetry properties almost

过离散型傅里叶变换的 公式，我们可以轻易推出离散型傅里 叶变换的公式。因为这两个公式几乎 相同。

If f (t ) is a non periodic sig nal, t h e

summation of t h e periodic

as sine and

cos in e)does

not

could artificially sig nal to make it transform( WFT )is one solution to

the problem of better represe nti ng

the non periodic

signal. Th e WF T can be used to give information about signals simultaneously in the time domain and in the freque ncy doma in

functions (such accurately sig

nal.You exte nd the periodic

represe nt

the but it would reqiure

additi on continuity at the

en dpo in ts.The win dow

Fourier

localize the signal in time.

and each secti on is an alyzed for its freque ncy content separately,

通过窗口傅里叶变换，输入信号f(t)被分成许多小部分，每个部分都能分别分析它的频率内容。如果信号有急剧的过度，就有必要对输入信号加窗，这样信号在端点处就会收敛于零。通过加权函数，即着眼于与中间部分而不是区间端点附近，这样就完成了加窗。加窗效应是将信号集中在同一个时间段。

To approximate a function by samples, and to approximate the Fourier integral by the discrete Fourier tran sform, requires applying a matrix whose order is the number sample points n. Since multipl ying an n*n matrix by a vector costs on the order of arithmetic operations, the problem gets quickly worse as the number of sample points in creases. However, if the samples are uniformly spaced, the n the Fourier

通过样本来近似函数，及通过离散傅立

叶傅立叶变换去逼近傅里叶积分，需要使用

一个矩阵，其顺序是全样本点的数量。通过

一个按n2算术运算顺序

的向量乘以一个n*n的矩阵，当采样点的增

多的时候，问题就迅速恶化。但是，如果样

本是均匀分布的，那么傅立叶矩阵可以被分

解成一个只有几个稀疏矩阵的乘积，以及由

此产生的因素可广泛应用在算术运算顺序共

向量。这就是所谓的快速傅里叶变换或

FFT。

3. 2. Con ti nu ous-time and discrete-

time systems

Physical systems in the broadest

sense are an in terc onnection of

comp onen ts, devices, or

subsystems. In con text ranging from

sig nal process ing and com muni

cati ons to electromecha ni cal

motors, automotive vehicles, and

chemical-process ing pla nts, a

system can be viewed as a process

in which in put sig nals are tran

sformed by the system or cause the

system to resp ond in some way,

result ing in other sig nals as outputs.

For example, a high-fidelity system

takes a recorded audio sig nal and

gen erates a reproducti on of that sig

nal. If the hi-fi system has tone con

trols, we can cha nge the tonal

quality of the reproduced sig

nal.Similarly, the circuit in Fig.3-1 can

be viewed as a system with in put

voltage Vs(t) and output voltage

Vc(t). An image- enhan ceme nt

system tran sforms an in put image

into an output image that has some

desired properties, such as improved

con trast.

A con ti nu ous-time system is a

system in which con ti nu ous-time in

put sig nals are applied and result in

con ti nu ous-time output sig nals. As

in Figure 3-1-5(a), where x(t) is the in

put, y(t) is the output, and h(t) is the

system impulse resp on se.Similarly,

a discrete-time system —that is, a

system that tran sforms discrete-time

in puts into discrete-time outputs —

is depicted as in Figure 3-1-5 (b).

Where x(n) is the in put, y(n) is the

output, and h(n) is the system un it

sample resp on se.

We can bring con ti nu ous- time

and discrete-time systems together

through the con cept of sampli ng,

and we can develop some in sights

into the use of discrete-time systems

to process con ti nu ous-time sig nals

that have bee n sampled.At prese nt,

many digital sig nal process ing

methods have bee n widely used in

scie nee and tech no logy fields. So

we take digital sig nal system for

example, some system properties

are described in n ext sect ion.

2.时间连续和时间离散系统物理系统

最直观的感觉就是，元器件、设备和子

系统的互连。在信号处理和通信，机电

马达，电动车，化学加工厂中，系统可

以视为一个处理，在这里，以某种方

法，信号会被系统传输或引起系统相

应，从而产生其他信号作为输出。例

如，一个高保真系统记录音频信号并重

放这信号。如果这高保真系统有音调控

制，我们可以改变所播放的声音的质

量。同样地，图3-1 可以视为一个带输

入电压Vs (t) 和输出电压Vc(t)的系

统。一个图像增强系统将输入图像转化

成所期望的输出图像，例如增强对比

度。

一个时间连续系统是输入连续信

号得到连续输出信号的系统。例如图

3-5a所描绘的，在这里，x(t) 是输入，

y(t)是输出，h(t)是系统脉冲相应。同

样地，时间离散系统是一个输入离散，

得到离散输出的系统，如图3-5b所描

绘的，在这里，x(n)是输入，y(n)是输

出，h(n)是系统单位抽样相应。

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我们可以通过抽样定理使时间连续和时间离散系统相结合。我们可以开发时间离散系统来处理已被抽样的时间连续信号。目前，很多数字信号处理方法已用在科学和技术领域。所以，我们取数字信号系统为例，它的一些系统特性将在下一部分描述。

4. 图像

图像解释题

图2-1

Any source of voltage, in cludi ng batteries, has two poi nts for electrical con tact. We can provide such a path for the battery by conn ect ing a piece of wire from one end of the battery to the other. Forming a circuit with a loop of wire, we will in itiate a continu ous flow of electr ons in a clockwise directi on, which is show n in Fig.2-1.

So long as the battery con ti nues to produce voltage and the con ti nuity of the electrical path isn ' t broken, electr ons will continue to flow in the

circuit. Follow ing the metaphor of

water movi ng through a pipe, this

con ti nu ous, uniform flow of electro

ns through the circuit is called a curre

nt. So long as the voltage source

keeps

“ pushing ” in the same

direction, the electron flow will

continue to move in the same

directi on in the circuit. This sin

gle-directi on flow of electro ns

is called a Direct Curre nt, or

DC. electro n circuits are

explored where the direct ion of

curre nt switches back and

forth: Alter nat ing Curre nt, or

AC. But for now, we ' ll just

concern ourselves with DC

circuits.

图2-2

We see that I is the only curre

nt flow ing into the no de.

However, there are three paths

for curre nt to leave the no de,

and these curre nt are represe

nted by I , I and I . Once charge

has en tered into the no de, it

has no place to go except to

leave ( this is known as con

servati on of charge) . The total

charge flow ing into a node

must be the same as the total

charge flow ing out of the no

de. So

I B+|C+I D=I A

Bringing everyth ing to the left side of

the above equati on, we get

(I B+I C+I D)-

I A=0

Then, the sum of all the curre nts is

zero. This can be gen eralized as

follows

艺I i=0

Note the conven tio n we have chose

n here: curre nt flow ing into the node

is take n to be n egative, and curre

nts flow ing out of the node are

positive.

图2-12

The PNP transistor is the king of

the traditi onal bipolar an alog in

tegrated circuits world. In fact in the

most basic and most cost effective

an alog IC process,

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the chip desig ner has at its disposal just that; a good NPN tran sistor. The rest, PNPs,

resistors and capacitors are just by-products , a no tch better tha n parasites. For in tuitive, back-of-the- env elope type an alysis, it is sufficie nt to model the tran sistor mostly in DC (Direct Curre nt), keep ing in mind that the ban

dwidth of such an element is finite.

When complexity, like small-sig nal AC (Alternate Current) behavior, is added to the model, computi ng simulati ons should be used since the math quickly

becomes hopeless. In Fig.2-12 the NPN transistor is shown with its symbol and its DC model. I n this comp onent the curre nt flow en ters the collector and base and exits the emitter. Simply stated, the tran sistor con ducts a collector curre nt I C which is a copy of the base curre nt I B amplified by a factor of beta B . It follows

The PNP tran sistor is

compleme ntary to the NPN, with the current flow entering the

emitter and exit ing the collector and base, the opposite of what happe ns in the NPN, which is show n in Fig.2-13. Simplicity dictates that PNPs are a by-product of the NPN con struct ion, hence they often have less beta curre nt gain and are slower than NPNs. A typical value for their amplificatio n factor

B

that the emitter curre nt I E is is 50 their cutoff freque ncy one plus beta times the base (f T ), is gen erally above 1 MH z. curre nt. A typical value for the amplification factor is 100. NPNs have excelle nt dyn amic performa nee, or ban dwidth, measured by their cutoff freque ncy; easily above 1GHz.

图 2-13