English On
Telecommunications
Unit 01
The Principle of PCM
四川邮电职业技术学院 2
Contents
?Course introduction
?Pre-reading Activities
?While-reading Activities
?New words and phrases
?Text organization
?Text and translation
?Post-reading Activities
?Further Development of the Theme-related
Specialized Knowledge
?Assignments
四川邮电职业技术学院 3
Course Introductin
? From this period on,we are going to learn English on
Telecommunications,which is one of the English for Science
and Technology (EST),（ What?s the characteristics of EST?)
? Learning this course,we will
enlarge our vocabulary in the field of
telecommunications and information;
get familiar with the terms in it;
get to know the characteristics of writing style of
telecommunications English and
master the translation skills of it;
thus greatly improve our professional qualities and
communicative competency in this globalized world in
the information age,
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Pre-reading Activities
? Ask the Ss the following two questions related to the theme of
the text,
? What is the heart of technology in communications in today’s
digital world？
Possible answers,
PCM,
? Why PCM?
Possible answers,
The stream of pulses and non-pulse streams of 1?s and
0?s are not easily affected by interference and noise,Even in
the presence of noise,the presence or absence of a pulse can
be easily determined,Since PCM is digital,a more general
reason would be that digital signals are easy to process by
cheap standard techniques,This makes it easier to implement
complicated communication systems such as telephone
networks (covered later in this course),返 回
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While-reading Activities / New
words and phrases
? principle ［‘ｐｒｉｎｓｉｐｌ］ n,原理
? sample ［‘ｓ ?ｍｐｌ］ vt,采样； 样值
? quantize ［‘ｋｗ ?ｎｔａｉｚ］ v,量化，分层
? scheme ［ｓｋｉ, ｍ］ n,方案，设计，安排
? describe ［ｄｉｓ‘ｋｒａｉｂ］ vt,叙述，描述
? amplitude ［‘ ?ｍｐｌｉｔｊｕ,ｄ］ n,幅，幅度
? binary ［‘ｂａｉｎ ?ｒｉ］ a,二进制的
? minimum ［‘ｍｉｎｉｍ ?ｍ］ n,最小值，最小量
? theoretical ［ θｉ ?‘ｒｅｔｉｋ ?ｌ］ a,理论上的
? repetition ［ｒｅｐｉ‘ｔｉ ??ｎ］ n,重复，反复
? maximum ［ ‘ m?ksim?ｍ ］ n,最大值
? reduce ［ｒｉ, ?ｄｊｕ,ｓ］ v,减少，缩小
? interchange ［ｉｎｔ ?? ?ｅｉｎ ?］ v,互换，转换
上 一 页 返 回
下 一 页
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While-reading Activities / New
words and phrases
? method ［‘ｍｅ θ?ｄ］ n,方式,方法,手段
? overcome ［ｏｕｖ ??ｋ ?ｍ］ v,克服,打败,征服
? environment ［ｉｎ‘ｖａｉ ?ｒ ?ｍ ?ｎｔ］ n,环境,周围情况
? lightning ［‘ｌａｉｔｎｉ ?］ n,电光，闪电，雷电
? strike ［ｓｔｒａｉｋ］ n,击，敲，打
? spark ［ｓｐ α:ｋ］ vi,发火花,打火,，闪光
? ignition ［ｉｇ‘ｎｉ ??ｎ］ n,点火,点火装置
? satellite ［‘ｓ ?ｔｉｌａｉｔ］ n,卫星
? terrestrial［ｔｉ‘ｒｅｓｔｒｉ ?ｌ］ a,地球的,地面的,大地的
? parameter［ｐ ??ｒ ?ｍｉｔ ?］ n,参数，系数
? attenuation n,衰减，衰耗
? inherent ［ｉｎ 'ｈｉ ?ｒ ?ｎｔ］ a,固有的，内在的
上 一 页 返 回 下 一 页
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While-reading Activities / New
words and phrases
? assume ［ ??ｓｊｕ,ｍ］ v,假设，假定
? decoder 解 (译 )码器
? interleave ［ｉｎｔ‘ｌｉ,ｖ］ vt,交插，交错，插接
? appropriate［ ??ｐｒｏｕｐｒｉｔ］ a,适当的，合适的
? unique ［ｊｕ, ?ｎｉｋ］ a,唯一的，独特的
? parameter ［ｐ ??ｒ ?ｍｉｔ ?］ 参数，系数
上 一 页 返 回 下 一 页
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While-reading Activities / New
words and phrases
? 抽样量化与编码 sampling,quantizing and coding
? 话路 speech channel
? 幅值 amplitude value
? 抽样频率 sampling frequency
? 抽样速率 sampling rate
? 脉冲流 stream of pulses
? 重复率 repetition rate
? 编码过程 coding process
? 模拟信号 analog signal
? 传输质量 transmission quality
? 数字通信 digital communication
? 数字传输 digital transmission
? 含噪声的环境 noisy environment
下 一 页 上 一 页
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While-reading Activities / New
words and phrases
? 传输路由 transmission path
? 信噪比 signal-to-noise ration
? 信号电平 signal levels
? 地面系统 terrestrial systems
? 噪声功率 noise power
? 二进制传输 binary transmission
? 反向操作 reverse operation
? 8-位码序列 8-digit sequence
? 接收端 receiving terminal
? 帧格式 frame format
? 同步字 synchronization word
上 一 页 返 回
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While-reading Activities / Text
organization
? 1,Ss read the text and point out the main idea of the
text,
?The main idea,The text mainly discusses the
principle of pulse code modulation
? 2,Ss make an analysis of the organization of the
text,
?The text may be divided into Three major sections,
?Section1 (Lines1-20),PCM?s 3 separate operations
and the ideal sampling frequency,
?Section2 (Lines21-40),the inherent advantage of
digital transmission for overcoming noisy
environments,
?Section3(Lines41-64),coding devices and process,返 回
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Text and translation
?The Principle of PCM(1)
翻 译 下 一 页 返 回
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Text and translation
? PCM is dependent on (2) three separate
operations,sampling,quantizing,and
coding (2’),Many different schemes for
performing (2) these three functions have
evolved during recent years,and we shall
describe the main ones,
翻译 下 一 页 上 一 页 返 回
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Text and translation
?In these descriptions we shall see how a
speech channel of telephone quality may be
conveyed as a series of amplitude values,
each value being represented (3),that is,
coded,as (3?) a sequence of 8 binary digits,
下 一 页 返 回 上 一 页 翻 译
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Text and translation
?Furthermore (4),we shall prove that a
minimum theoretical sampling frequency of
order 6.8 kilohertz (kHz) is required to
convey a voice channel occupying the range
300 Hz to 3.4 kHz(4a),Practical equipments,
however,normally use a sampling rate of 8
kHz,and if 8-digits per sample value are
used,the voice channel becomes
represented by a stream of pulses (4b) with a
repetition rate of 64 kHz,Fig,1-1 illustrates
the sampling,quantizing,and coding
processes,
下 一 页 返 回 上 一 页 翻译
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Text and translation
? Reexamination of our simple example
shows us that the speech signal of
maximum (5) frequency 3.4 kHz has been
represented by a signal of frequency64 kHz,
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Text and translation
?However,if only 4-digits per sample value
had been used,the quality of transmission
would drop,and the repetition rate of the
pulses would be reduced to 32 kHz,Thus the
quality of transmission is dependent on the
pulse repetition rate,and for digital
communication systems these two variables
may be interchanged most efficiently,
下 一 页 返 回 上 一 页 翻 译
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Text and translation
? Digital transmission provides a powerful
method for overcoming noisy environments,
Noise can be introduced into transmission
path in many different ways; perhaps via a
nearby lightning strike,the sparking of a car
ignition system,or the thermal low-level
noise (6) within the communication
equipment itself,
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Text and translation
?It is the relationship of the true signal to the
noise signal,known as the signal-to-noise
ratio (7) which is of the most interest to (7?) the
communication engineer,Basically,if the
signal is very large compared to the noise
level,(7a) then a perfect message can take
place; however,this is not always the case
(7b),
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Text and translation
?For example,the signal received from a
satellite,located in far outer space (8),is very
weak and is at a level only slightly above
that of the noise,Alternative examples (8?)
may be found within terrestrial systems
where,although the message signal is
strong,so is the noise power,
翻 译 下 一 页 返 回 上 一 页
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Text and translation
? If we consider binary transmission,the
complete information about a particular
message will always be obtained by simply
detecting the presence or absence of the
pulse,
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Text and translation
?By comparison(9),most other forms of
transmission systems convey the message
information using the shape,or level of the
transmitted signal (9?); parameters that are
most easily affected by the noise and
attenuation introduced by the transmission
path,
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Text and translation
?Consequently (10) there is an inherent
advantage (10?) for overcoming noisy
environments by choosing digital
transmission,
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Text and translation
? So far in this discussion we have assumed
that each voice channel has a separate
coder,the unit that converts sampled
amplitude values to a set of pulses; and
decoder,the unit that performs the reverse
operation (11),This need not be so and
systems are in operation where a single
codec (i.e.,coder and its associated decoder)
is shared between 24,30,or even 120
separate channels,
翻 译 下 一 页 上 一 页 返 回
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Text and translation
?A high-speed electronic switch (12a) is used
to present the analog information signal of
each channel,taken in turn (12b),to the codec,
The codec is then arranged to sequentially
sample the amplitude value,and code (12c)
this value into the 8-digit sequence,
下 一 页 返 回 上 一 页 翻 译
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Text and translation
?Thus the output to the codec may be seen
as a sequence of 8 pulses relating to
channel 1,then channel 2,and so on,This
unit is called a time division multiplexer
(TDM),and is illustrated in Fig,1-2 (13),The
multiplexing principle that is used is known
as word interleaving,Since the words,or 8-
digit sequences,are interleaved in time,
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Text and translation
? At the receive terminal a de-multiplexer
is arranged to separate the 8-digit
sequences into the appropriate (14) channels,
The reader may ask,how does the de-
multiplexer know which group of 8-digits
relates to channel 1,2,and so on? Clearly
this is important!
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Text and translation
? The problem is easily overcome by
specifying a frame format (15a),where at the
start of each frame a unique sequence of
pulses called the frame code (15b),or
synchronization word (15c),is placed so as
to(15d) identify the start of the frame,
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Text and translation
?A circuit of the de-multiplexer is arranged to
detect the synchronization word,and
thereby it knows that the next group of 8-
digits corresponds to channel 1,The
synchronization word reoccurs once again
after the last channel has been received,
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Text and translation
?与本单元课题有关的电信术语或用语 。
下 一 页 上 一 页 返 回
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Post-reading Activities
?i,Review the important expressions,
phrases or sentences which were learnt in
the text by guiding the students through
Exercises 1-2 between Page 18 and Page 19
in class,
下 一 页 上 一 页
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Post-reading Activities
?ii,Ask the students to summarize the
translation skills touched upon in the study
of the text,
上 一 页 返 回
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Further Development of the Theme-
related Specialized Knowledge
?PCM原理及应用可参考网络资源,
?http://www.webopedia.com/TERM/P/PCM.htm
l
?http://www.itu.int/search/pages/ituwebsearch
/basic.asp?QuerySubmit=true&QueryText=pc
m
?韩其顺和王学铭主编,英汉科技翻译教程。上海：
上海外语教育出版社。 2003年 1月。
?张韵斐。现代英语词汇学概论。北京：北京师范
大学出版社。 2003年 1月。
返 回
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Assignments
?1.Preview Unit 02
?2.Do Exercises3-5 between Page 19－ 22
返 回
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本单元结束！
谢 谢！！
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?以下幻灯片为翻译及注释内容
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Text and translation
?课文题目,PCM原理
课 文
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Text and translation
?PCM的构成依赖于三个环节,即采样、量化和编
码, 近年来,人们对这三个环节的实现提出了许多
不同的方案,我们将对其中一些主要的方案进行讨
论,
课 文
四川邮电职业技术学院 38
Text and translation
?在这些讨论中,我们会看到话路中的语声信号是如
何转换成一个幅值序列的,而每个幅值又被编码,
即以 8位二进制数的序列表示,
课 文
四川邮电职业技术学院 39
Text and translation
?而且,我们将证明,为了变换频率范围
300Hz~3.4KHz的话路信号,理论上的最小采样频
率为 608KHz.但是,实际设备通常用 8KHz的采样
速率,而如果每个样值用 8位码的话,则话路是由一
个重复速率为 64KHz的脉冲流来表示的, 图 1-1表
示了采样、量化和编码的过程,
课 文
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Text and translation
?让我们再研究一下上面提到的简单例子,可以看
出,最高频率为 3.4KHz的话音信号是用 64KHZ的
(脉冲流 )信号来表示的,
课 文
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Text and translation
?但是,如果每个样值只用 4位码表示,则传输质量会
下降,而脉冲的重复速率也将减小到 32KHz.因而
传输质量是取决于脉冲重复速率的,对于数字通信
系统,这两个量之间极明显地相互影响着,
课 文
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Text and translation
?数字传输对于克服噪声环境的影响提供了一个强
有力的手段,噪声可以以多种不同的方式进入传输
信道,比如说因为附近的闪电、汽车点火系统的打
火或因通信设备本身低电平所致,
课 文
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Text and translation
?正是这种被称为信噪比的即真实信号与噪声的关
系引起了通信工程师的极大的兴趣,从本质上讲,
如果信号比噪声电平大得多,则信息的传输是完美
的,但是,实际情况并不总是这样,
课 文
四川邮电职业技术学院 44
Text and translation
?例如,从位于遥远太空中的卫星接收的信号极其
微弱,其电平仅比噪声稍高一点,地面系统则是另
一类例子,尽管信号很强,噪声也很强,
课 文
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Text and translation
?研究二进制信号的传输可见,只要简单地去判别脉
冲的”有”和”无”,我们就获得了一条消息的全
部信息,
课 文
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Text and translation
?相比之下,许多其他形式的传输系统是利用被传信
号的波形或电平来传送信息的,而这些参数又极易
受到传输途径中的噪声和衰耗的影响,
课 文
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Text and translation
?因此选择数字传输系统在克服噪声环境方面有其
固有的优势,
课 文
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Text and translation
?到目前为止,在这个讨论中,我们一直假定每个话
路各有一个编码器和解码器,前者是将幅度采样值
变成脉冲,而后者施行相反的变换,这种设置并非
必需,在实际运行的 PCM系统中,单一的编、译码
器为 24路,30路,甚至 120路所共用 (注, 在当代
PCM设备中,编、译码器系分路设备,即每个话路
各有一套,)
课 文
四川邮电职业技术学院 49
Text and translation
?一个高速的电子开关被用来将每一话路的模拟信
号依次地送往编、译码器,然后编、译码器再顺序
采样幅值并把这个幅值编成 8位码序列,
课 文
四川邮电职业技术学院 50
Text and translation
?因此从编译码器输出的信息就是一个分别对应于
话路 1,话路 2,等等的 8位码序列, 这种设备称为
时分复用,如图 1-2所示, 音域 8位码的码字序列按
时间顺序插接在一起,所以上面的复用原则称为码
字插接,
课 文
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Text and translation
?接收端设置了分路设备,将 8位码序列分配到相应
的话路中,读者也许会问,分路设备怎么知道哪一
个 8位码组对应于第 1路、第 2路极其他各路呢?显
然这是很重要的,
课 文
四川邮电职业技术学院 52
Text and translation
?这个问题是很容易解决的,我们只要指定一个帧格
式,即在每一帧的开始放置一个被称作帧码或同步
字的独特的码序列以标志每帧的起始,
课 文
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Text and translation
?而用分路设备的一个电路去检测同步字,从而就可
知道下一个 8位码组对应于话路 1.当最后一个话
路的码字收到之后,同步码字有再次出现,
课 文
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While-reading Activities /
Key language points
?1.本篇课文涉及数字通信领域，题目为：,PCM
原理”,
四川邮电职业技术学院 55
While-reading Activities /
Key language points
?2,be dependent on 依靠，依赖，取决于,
?2?,performing是 perform的动名词,动名词虽为名词，
但 仍保留着动词的某些特征，例如它仍可带有动词宾语,
本句中的 these three functions就是 performing的宾语,
本课中这类例子很多，例如第四段中的最后一句中,
Consequently there is an inherent advantage for
overcoming noisy environments by choosing digital
transmission,
句中的 overcoming和 choosing都是动名词且带有自己
的动词宾语,
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While-reading Activities /
Key language points
? 另有理论认为ＰＣＭ分为四过程，如下,
? The practical implementation of PCM makes use of other
processes,The processes are carried out in the order in which
they appear below,
Filtering
Sampling
Quantizing
Encoding
The filtering stage removes frequencies above the highest
signal frequency,These frequencies if not removed,may
cause problems when the signal is going through the stage of
sampling,Sampling of a waveform means determining
instantaneous amplitudes of a signal at fixed intervals,You
may have a problem in understanding what this sentence
means,but if you take time to look at Figure 7 on the following
Slide,you should be able to understand,
四川邮电职业技术学院 57
While-reading Activities /
Key language points
? 3,each value being represented这是一种独立分词结
构，用来表示一种伴随状态，作状语,可译成：“而每一
幅值被表示为”,独立分词结构在科技文章中相当常见，
例如,
There are many kinds of steel,each having its uses
in industry,
译为：“钢有许多种，在工业中每种都有它自己的用
途”,
独立分词结构还可以表示时间、原因或条件等，对主句
进行补充说明,例如表示原因,
The resistance being very high,the current in the
circuit was low,
译为,“由于电阻很高，故电路里的电流很小”,
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While-reading Activities /
Key language points
?(3?).as a sequence of 8 binary digits句中的 as
意为“作为，表为，成为”,该短语可译成,“(表
为 )8位二进制码的序列”,
四川邮电职业技术学院 59
While-reading Activities /
Key language points
? 4,furthermore,adv.“而且；此
外”
Furthermore,these child-
raising families may raise other
people‘s children in addition to
their own,而且,这些抚养孩子的
家庭除了自己的孩子外也可以抚养
其他人家的孩子。
The house is too small,and
furthermore,it's too far from the
office,这座房子太小,而且离办公
地点也太远。
? 同义词, again,also,besides,by
the same token,in addition,
likewise,similarly,then,too,
? (4a) 脉冲流
? (4b),occupying是 occupy的
现在分词,
动词的 -ing形式可以作为名
词用，称为动名词，本课注释
(2)已对此作了介绍。动词的 -
ing形式亦可作形容词用 (称现
在分词 ).它一般修饰该动作的
发出者，而且它亦可带有自己
的宾语，例如本句中的,“a
voice channel occupying
the range 300Hz to 3.4kHz”,
该短语可译为,“占有 300Hz到
3.4kHz频率范围的话路”,
四川邮电职业技术学院 60
While-reading Activities /
Key language points
?5,n.(pl,maximums,-ma[-mE])最大量 ; 最大数 ;
最高点极点 ; 最高额,最大限度 【 数 】 极大 (值 );
最大 (值 )(发展的 )顶峰时期
reach a maximum 达到顶点
The excitement was at its maximum,
兴奋到极点。
The sound has reached its maximum,声音
达到最高音位。
?反义词,minimum
四川邮电职业技术学院 61
While-reading Activities /
Key language points
?6.本句中的几个词组可译为,
lightning strike 打雷
sparking of a car ignition system 汽车点
火系统的打火
thermal low-level noise 低电平的热噪声
四川邮电职业技术学院 62
While-reading Activities /
Key language points
? 7,known as the signal-
to-noise ratio 译为“称
为信号噪声比”,
? 7?,Be of + n,结构
Be of importance=be
important
be of the most interest
to= be most interesting
to
? 7a,compared to the
noise level 意为,“与噪声
电平相比”,
? 7b,this is not always
the case,实际情况并非
如此,
四川邮电职业技术学院 63
While-reading Activities /
Key language points
? 8,located in far outer space这
是一种分词短语结构,located是动
词的 -ed形式，称为过去分词，起
形容词的作用，在句中作定语,这
种分词往往用来修饰原来动词动作
的承受者,
例如,
The trees planted by me have
grown up.“我种的树已长大了,”
再例如,
Electromotive force results in
electrical pressure,compared
to water pressure.“电动势产生电
压，电压好比水压”
所以课文中的这一短语可译为,“位
于遥远太空中的 (卫星 )”,
? 8?,Alternative adj.随便一个的；
二者择一的 (三者或以上的选择用
choice)
The way was blocked,so we
went by an alternative road.这
条路被挡住了，因此我们走了另一
条路。
n,抉择；选择余地
I wanted to go out,but I had
no money,I had no alternative
but to staying at home.我想出去，
可是没钱；只能待在家里。
We have no alternative but
to go on.除了继续下去,我们没有
选择的余地。
There was no other
alternative but to fight till the
victory.除了战斗直到胜利,别无选
择。
四川邮电职业技术学院 64
While-reading Activities /
Key language points
? 9,By comparison 相比之下
? 9?,using the shape,or level of transmitted signal 为现在分词
短语结构，作伴随情况状语，可译为,“用传输信号的波形或电平 (来
传送信息 )”,
类似的例子还有,
The rockets rose hissing over the launching site.“火箭在发
射场的上空嘶嘶地上升,”
再例如,
They sat together,carefully studing the design of the
circuits,
,他们坐在一起仔细地研究着那些电路的设计,”
对课文中的这个句子，全句可译为,“相比之上，许多其他形式的
传输系统是利用被传信号的波形或电平来传送信息的，而这些参数
又极易受到传输途径中的噪声和衰耗的影响,”
四川邮电职业技术学院 65
While-reading Activities /
Key language points
? 10.consequently,adv.,
conj.所以，因此
Mr,Foster has never
been to China,
Consequently / Hence
he knows very little
about it."福斯特先生从
未去过中国,所以对中国了
解得很少。,
同义词,accordingly,
hence,as a result,
therefore,
10’,inherent advantage
固有的优势,
四川邮电职业技术学院 66
While-reading Activities /
Key language points
?11,So far in this discussion we have assumed that
each voice channel has a separate coder,the unit
that converts sampled amplitude values to a set of
pulses; and decoder,the unit that performs the
reverse operation,本句理解和翻译应注意结构的分
析,在宾语从句 that each voice channel has… 中
has带了两个并列的宾语 coder,decoder；且这两个成
分又分别带了非限制性定语从句,
四川邮电职业技术学院 67
While-reading Activities /
Key language points
? 12a,A high-speed
electronic switch, 一个
高速电子开关
? 14b,taken in turn 轮流
地，依次地
? 12c,Code 此处作动词，
编码,
四川邮电职业技术学院 68
While-reading Activities /
Key language points
四川邮电职业技术学院 69
While-reading Activities /
Key language points
?14,appropriate,adj.适合的 ; 适当的 ; 相称的
appropriate example适当的例子
appropriate manners适当的态度
Write in a style appropriate to your subject.
用与你的题目相称的体裁写。
Ordinary shoes are not appropriate to resist
the electricity.普通鞋不适于抗电击。
四川邮电职业技术学院 70
While-reading Activities /
Key language points
?15a,specifying a frame format 指定一个帧格
式
?15b,the frame code:帧码
?15c,synchronization word：同步字
?15d,so as to 以便，为了,
四川邮电职业技术学院 71
While-reading Activities /
Key language points
四川邮电职业技术学院 72
While-reading Activities /
Key language points
四川邮电职业技术学院 73
Text & Translation,
? 16,与本单元课题有关的电信术语或用语,
? 称作同步字的独特码序列
a unique sequence of pulses called synchronization word
? 涉及到第一, 第二及其它各路的序列
a sequence relating to channel 1,2 and so on
? 将抽样的幅值转换成一串脉冲的单元
the unit that converts sampled amplitude value to a set of pulses
? 由传输路由引入的衰减
the attenuation introduced by transmission path
? 被传信号的波形 the shape of transmitted signal
? 一条特定消息中的全部信息
the complete information about a particular message
? 由卫星上收到的信号 the signal received from a satellite
? 真实信号与噪声信号间的关系
relationship of the true signal to the noise signal
下 一 页
四川邮电职业技术学院 74
Text & Translation,
? 16,与本单元课题有关的电信术语或用语,
? 实现这三项功能的方案 the schemes for performing these 3 functions
? 一串幅值 a series of amplitude value
? 电话质量的话路 a speech channel of telephone quality
? 理论上最小取样频率 a minimum theoretical sampling frequency
? 汽车点火系统的打火 the sparking of a car ignition system
? 脉冲的, 有, 和, 无, the presence or absence of the pulse
? 时分多路复用器 Time Division Multiplexer
? 高速电子开关 a high-speed electronic switch
? 重复率为 64khz的脉冲流 the stream of the pulses with a repetition of 64 khz
上 一 页
四川邮电职业技术学院 75
Course Introductin----EST’s
features
? English for Science and Technology (EST),
? The Study focusing on EST began in 1950s,EST
has its own features in writing style,vocabulary,
grammar and rhetorical devices,
? Generally speaking,EST lays more emphasis on
scientificalness,logic,accuracy and strictness
instead of literary grace,Thus its writing often is
filled with nominalized phrases,passive voiced
sentences,non-restrictive attributive clauses and
postpositional determiners etc,
? Therefore,in understanding and translating the
material of EST,we lay more emphasis on
faithfulness,expressiveness and accurateness (信,
达,切 ) rather than faithfulness,expressiveness and
elegance( 信，达，雅,which advocated by Yanfu),
返 回
四川邮电职业技术学院 76
Course Introduction----EST’s
features
? Vocabulary Studying Tips
Get Familiar with certain lexicological devices
(word-formation);
Grasp the words? meaning in the concrete
registers (context,fields of science),
Read more related materials and do more
translation,Practice and repetition is the mother of
memory,
返 回
四川邮电职业技术学院 77
Course Introduction----
Vocabulary Studying Tips
? lexicological devices (word-formation);
(a),Compounding or composition ( about 27%),
raindrop pulse code modulation
(b),Derivation of affixation (about 17.5%)
Prefixation,decode synchronization
suffixation,modulation coder
(c),Conversion (about 10.5%),code
(d),Initialisms and acronyms （ about 9%),
PCM CCITT UNESCO NATO
(e),Blending (about 6%) TELEX
(f),Neoclassical formations (about 4%) psychedelic neuroliguistic
(g),Reduplication (about 0.5%) walkie-talkie
(h),Clipping (about 2%) phone lab
返 回
四川邮电职业技术学院 78
Course Introduction----EST’s
features
? Vocabulary Studying Tips
? Get Familiar with certain lexicological
devices;
? Grasp the words? meaning in the
concrete registers (context,fields of
science),
EYE,眼睛
inspection eye
hoisting eye
observing eye
television eye
flower eye
CELL 蜂窝，蜂房
The nucleus is the information center of
the cell,
细胞核是 细胞 的信息中枢。
He was imprisoned in a cell,
他被关在监狱的 单人小牢房 中。
In the center of the spacious workshop
stood a cell with packets of block
anodes,
在宽敞的车间中央有一个装有一组组阳极板
的 电解槽 。
When the ends of a copper wire are
joined to a device called an electric
cell a steady stream of electricity
flows through the wire,
当把一根铜丝的两端连接到一种叫做
电池 的电器上时，就会有稳定的电流
流过该铜丝。
A basic cellular system consists
of three parts,a mobile unit,a cell
site,and a MTSO,
一个蜂窝式系统基本上由三部分组成：
移动机，无线基站和电话交换就局。
Why one common word has so
many different scientific meanings?
返 回
Telecommunications
Unit 01
The Principle of PCM
四川邮电职业技术学院 2
Contents
?Course introduction
?Pre-reading Activities
?While-reading Activities
?New words and phrases
?Text organization
?Text and translation
?Post-reading Activities
?Further Development of the Theme-related
Specialized Knowledge
?Assignments
四川邮电职业技术学院 3
Course Introductin
? From this period on,we are going to learn English on
Telecommunications,which is one of the English for Science
and Technology (EST),（ What?s the characteristics of EST?)
? Learning this course,we will
enlarge our vocabulary in the field of
telecommunications and information;
get familiar with the terms in it;
get to know the characteristics of writing style of
telecommunications English and
master the translation skills of it;
thus greatly improve our professional qualities and
communicative competency in this globalized world in
the information age,
返 回
四川邮电职业技术学院 4
Pre-reading Activities
? Ask the Ss the following two questions related to the theme of
the text,
? What is the heart of technology in communications in today’s
digital world？
Possible answers,
PCM,
? Why PCM?
Possible answers,
The stream of pulses and non-pulse streams of 1?s and
0?s are not easily affected by interference and noise,Even in
the presence of noise,the presence or absence of a pulse can
be easily determined,Since PCM is digital,a more general
reason would be that digital signals are easy to process by
cheap standard techniques,This makes it easier to implement
complicated communication systems such as telephone
networks (covered later in this course),返 回
四川邮电职业技术学院 5
While-reading Activities / New
words and phrases
? principle ［‘ｐｒｉｎｓｉｐｌ］ n,原理
? sample ［‘ｓ ?ｍｐｌ］ vt,采样； 样值
? quantize ［‘ｋｗ ?ｎｔａｉｚ］ v,量化，分层
? scheme ［ｓｋｉ, ｍ］ n,方案，设计，安排
? describe ［ｄｉｓ‘ｋｒａｉｂ］ vt,叙述，描述
? amplitude ［‘ ?ｍｐｌｉｔｊｕ,ｄ］ n,幅，幅度
? binary ［‘ｂａｉｎ ?ｒｉ］ a,二进制的
? minimum ［‘ｍｉｎｉｍ ?ｍ］ n,最小值，最小量
? theoretical ［ θｉ ?‘ｒｅｔｉｋ ?ｌ］ a,理论上的
? repetition ［ｒｅｐｉ‘ｔｉ ??ｎ］ n,重复，反复
? maximum ［ ‘ m?ksim?ｍ ］ n,最大值
? reduce ［ｒｉ, ?ｄｊｕ,ｓ］ v,减少，缩小
? interchange ［ｉｎｔ ?? ?ｅｉｎ ?］ v,互换，转换
上 一 页 返 回
下 一 页
四川邮电职业技术学院 6
While-reading Activities / New
words and phrases
? method ［‘ｍｅ θ?ｄ］ n,方式,方法,手段
? overcome ［ｏｕｖ ??ｋ ?ｍ］ v,克服,打败,征服
? environment ［ｉｎ‘ｖａｉ ?ｒ ?ｍ ?ｎｔ］ n,环境,周围情况
? lightning ［‘ｌａｉｔｎｉ ?］ n,电光，闪电，雷电
? strike ［ｓｔｒａｉｋ］ n,击，敲，打
? spark ［ｓｐ α:ｋ］ vi,发火花,打火,，闪光
? ignition ［ｉｇ‘ｎｉ ??ｎ］ n,点火,点火装置
? satellite ［‘ｓ ?ｔｉｌａｉｔ］ n,卫星
? terrestrial［ｔｉ‘ｒｅｓｔｒｉ ?ｌ］ a,地球的,地面的,大地的
? parameter［ｐ ??ｒ ?ｍｉｔ ?］ n,参数，系数
? attenuation n,衰减，衰耗
? inherent ［ｉｎ 'ｈｉ ?ｒ ?ｎｔ］ a,固有的，内在的
上 一 页 返 回 下 一 页
四川邮电职业技术学院 7
While-reading Activities / New
words and phrases
? assume ［ ??ｓｊｕ,ｍ］ v,假设，假定
? decoder 解 (译 )码器
? interleave ［ｉｎｔ‘ｌｉ,ｖ］ vt,交插，交错，插接
? appropriate［ ??ｐｒｏｕｐｒｉｔ］ a,适当的，合适的
? unique ［ｊｕ, ?ｎｉｋ］ a,唯一的，独特的
? parameter ［ｐ ??ｒ ?ｍｉｔ ?］ 参数，系数
上 一 页 返 回 下 一 页
四川邮电职业技术学院 8
While-reading Activities / New
words and phrases
? 抽样量化与编码 sampling,quantizing and coding
? 话路 speech channel
? 幅值 amplitude value
? 抽样频率 sampling frequency
? 抽样速率 sampling rate
? 脉冲流 stream of pulses
? 重复率 repetition rate
? 编码过程 coding process
? 模拟信号 analog signal
? 传输质量 transmission quality
? 数字通信 digital communication
? 数字传输 digital transmission
? 含噪声的环境 noisy environment
下 一 页 上 一 页
四川邮电职业技术学院 9
While-reading Activities / New
words and phrases
? 传输路由 transmission path
? 信噪比 signal-to-noise ration
? 信号电平 signal levels
? 地面系统 terrestrial systems
? 噪声功率 noise power
? 二进制传输 binary transmission
? 反向操作 reverse operation
? 8-位码序列 8-digit sequence
? 接收端 receiving terminal
? 帧格式 frame format
? 同步字 synchronization word
上 一 页 返 回
四川邮电职业技术学院 10
While-reading Activities / Text
organization
? 1,Ss read the text and point out the main idea of the
text,
?The main idea,The text mainly discusses the
principle of pulse code modulation
? 2,Ss make an analysis of the organization of the
text,
?The text may be divided into Three major sections,
?Section1 (Lines1-20),PCM?s 3 separate operations
and the ideal sampling frequency,
?Section2 (Lines21-40),the inherent advantage of
digital transmission for overcoming noisy
environments,
?Section3(Lines41-64),coding devices and process,返 回
四川邮电职业技术学院 11
Text and translation
?The Principle of PCM(1)
翻 译 下 一 页 返 回
四川邮电职业技术学院 12
Text and translation
? PCM is dependent on (2) three separate
operations,sampling,quantizing,and
coding (2’),Many different schemes for
performing (2) these three functions have
evolved during recent years,and we shall
describe the main ones,
翻译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 13
Text and translation
?In these descriptions we shall see how a
speech channel of telephone quality may be
conveyed as a series of amplitude values,
each value being represented (3),that is,
coded,as (3?) a sequence of 8 binary digits,
下 一 页 返 回 上 一 页 翻 译
四川邮电职业技术学院 14
Text and translation
?Furthermore (4),we shall prove that a
minimum theoretical sampling frequency of
order 6.8 kilohertz (kHz) is required to
convey a voice channel occupying the range
300 Hz to 3.4 kHz(4a),Practical equipments,
however,normally use a sampling rate of 8
kHz,and if 8-digits per sample value are
used,the voice channel becomes
represented by a stream of pulses (4b) with a
repetition rate of 64 kHz,Fig,1-1 illustrates
the sampling,quantizing,and coding
processes,
下 一 页 返 回 上 一 页 翻译
四川邮电职业技术学院 15
Text and translation
? Reexamination of our simple example
shows us that the speech signal of
maximum (5) frequency 3.4 kHz has been
represented by a signal of frequency64 kHz,
翻 译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 16
Text and translation
?However,if only 4-digits per sample value
had been used,the quality of transmission
would drop,and the repetition rate of the
pulses would be reduced to 32 kHz,Thus the
quality of transmission is dependent on the
pulse repetition rate,and for digital
communication systems these two variables
may be interchanged most efficiently,
下 一 页 返 回 上 一 页 翻 译
四川邮电职业技术学院 17
Text and translation
? Digital transmission provides a powerful
method for overcoming noisy environments,
Noise can be introduced into transmission
path in many different ways; perhaps via a
nearby lightning strike,the sparking of a car
ignition system,or the thermal low-level
noise (6) within the communication
equipment itself,
翻 译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 18
Text and translation
?It is the relationship of the true signal to the
noise signal,known as the signal-to-noise
ratio (7) which is of the most interest to (7?) the
communication engineer,Basically,if the
signal is very large compared to the noise
level,(7a) then a perfect message can take
place; however,this is not always the case
(7b),
返 回 上 一 页 下 一 页 翻译
四川邮电职业技术学院 19
Text and translation
?For example,the signal received from a
satellite,located in far outer space (8),is very
weak and is at a level only slightly above
that of the noise,Alternative examples (8?)
may be found within terrestrial systems
where,although the message signal is
strong,so is the noise power,
翻 译 下 一 页 返 回 上 一 页
四川邮电职业技术学院 20
Text and translation
? If we consider binary transmission,the
complete information about a particular
message will always be obtained by simply
detecting the presence or absence of the
pulse,
翻 译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 21
Text and translation
?By comparison(9),most other forms of
transmission systems convey the message
information using the shape,or level of the
transmitted signal (9?); parameters that are
most easily affected by the noise and
attenuation introduced by the transmission
path,
下 一 页 返 回 翻 译 上 一 页
四川邮电职业技术学院 22
Text and translation
?Consequently (10) there is an inherent
advantage (10?) for overcoming noisy
environments by choosing digital
transmission,
下 一 页 返 回 翻 译 上 一 页
四川邮电职业技术学院 23
Text and translation
? So far in this discussion we have assumed
that each voice channel has a separate
coder,the unit that converts sampled
amplitude values to a set of pulses; and
decoder,the unit that performs the reverse
operation (11),This need not be so and
systems are in operation where a single
codec (i.e.,coder and its associated decoder)
is shared between 24,30,or even 120
separate channels,
翻 译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 24
Text and translation
?A high-speed electronic switch (12a) is used
to present the analog information signal of
each channel,taken in turn (12b),to the codec,
The codec is then arranged to sequentially
sample the amplitude value,and code (12c)
this value into the 8-digit sequence,
下 一 页 返 回 上 一 页 翻 译
四川邮电职业技术学院 25
Text and translation
?Thus the output to the codec may be seen
as a sequence of 8 pulses relating to
channel 1,then channel 2,and so on,This
unit is called a time division multiplexer
(TDM),and is illustrated in Fig,1-2 (13),The
multiplexing principle that is used is known
as word interleaving,Since the words,or 8-
digit sequences,are interleaved in time,
下 一 页 返 回 上 一 页 翻译
四川邮电职业技术学院 26
Text and translation
? At the receive terminal a de-multiplexer
is arranged to separate the 8-digit
sequences into the appropriate (14) channels,
The reader may ask,how does the de-
multiplexer know which group of 8-digits
relates to channel 1,2,and so on? Clearly
this is important!
翻 译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 27
Text and translation
? The problem is easily overcome by
specifying a frame format (15a),where at the
start of each frame a unique sequence of
pulses called the frame code (15b),or
synchronization word (15c),is placed so as
to(15d) identify the start of the frame,
翻 译 下 一 页 上 一 页 返 回
四川邮电职业技术学院 28
Text and translation
?A circuit of the de-multiplexer is arranged to
detect the synchronization word,and
thereby it knows that the next group of 8-
digits corresponds to channel 1,The
synchronization word reoccurs once again
after the last channel has been received,
下 一 页 返 回 上 一 页 翻 译
四川邮电职业技术学院 29
Text and translation
?与本单元课题有关的电信术语或用语 。
下 一 页 上 一 页 返 回
四川邮电职业技术学院 30
Post-reading Activities
?i,Review the important expressions,
phrases or sentences which were learnt in
the text by guiding the students through
Exercises 1-2 between Page 18 and Page 19
in class,
下 一 页 上 一 页
四川邮电职业技术学院 31
Post-reading Activities
?ii,Ask the students to summarize the
translation skills touched upon in the study
of the text,
上 一 页 返 回
四川邮电职业技术学院 32
Further Development of the Theme-
related Specialized Knowledge
?PCM原理及应用可参考网络资源,
?http://www.webopedia.com/TERM/P/PCM.htm
l
?http://www.itu.int/search/pages/ituwebsearch
/basic.asp?QuerySubmit=true&QueryText=pc
m
?韩其顺和王学铭主编,英汉科技翻译教程。上海：
上海外语教育出版社。 2003年 1月。
?张韵斐。现代英语词汇学概论。北京：北京师范
大学出版社。 2003年 1月。
返 回
四川邮电职业技术学院 33
Assignments
?1.Preview Unit 02
?2.Do Exercises3-5 between Page 19－ 22
返 回
四川邮电职业技术学院 34
本单元结束！
谢 谢！！
四川邮电职业技术学院 35
?以下幻灯片为翻译及注释内容
四川邮电职业技术学院 36
Text and translation
?课文题目,PCM原理
课 文
四川邮电职业技术学院 37
Text and translation
?PCM的构成依赖于三个环节,即采样、量化和编
码, 近年来,人们对这三个环节的实现提出了许多
不同的方案,我们将对其中一些主要的方案进行讨
论,
课 文
四川邮电职业技术学院 38
Text and translation
?在这些讨论中,我们会看到话路中的语声信号是如
何转换成一个幅值序列的,而每个幅值又被编码,
即以 8位二进制数的序列表示,
课 文
四川邮电职业技术学院 39
Text and translation
?而且,我们将证明,为了变换频率范围
300Hz~3.4KHz的话路信号,理论上的最小采样频
率为 608KHz.但是,实际设备通常用 8KHz的采样
速率,而如果每个样值用 8位码的话,则话路是由一
个重复速率为 64KHz的脉冲流来表示的, 图 1-1表
示了采样、量化和编码的过程,
课 文
四川邮电职业技术学院 40
Text and translation
?让我们再研究一下上面提到的简单例子,可以看
出,最高频率为 3.4KHz的话音信号是用 64KHZ的
(脉冲流 )信号来表示的,
课 文
四川邮电职业技术学院 41
Text and translation
?但是,如果每个样值只用 4位码表示,则传输质量会
下降,而脉冲的重复速率也将减小到 32KHz.因而
传输质量是取决于脉冲重复速率的,对于数字通信
系统,这两个量之间极明显地相互影响着,
课 文
四川邮电职业技术学院 42
Text and translation
?数字传输对于克服噪声环境的影响提供了一个强
有力的手段,噪声可以以多种不同的方式进入传输
信道,比如说因为附近的闪电、汽车点火系统的打
火或因通信设备本身低电平所致,
课 文
四川邮电职业技术学院 43
Text and translation
?正是这种被称为信噪比的即真实信号与噪声的关
系引起了通信工程师的极大的兴趣,从本质上讲,
如果信号比噪声电平大得多,则信息的传输是完美
的,但是,实际情况并不总是这样,
课 文
四川邮电职业技术学院 44
Text and translation
?例如,从位于遥远太空中的卫星接收的信号极其
微弱,其电平仅比噪声稍高一点,地面系统则是另
一类例子,尽管信号很强,噪声也很强,
课 文
四川邮电职业技术学院 45
Text and translation
?研究二进制信号的传输可见,只要简单地去判别脉
冲的”有”和”无”,我们就获得了一条消息的全
部信息,
课 文
四川邮电职业技术学院 46
Text and translation
?相比之下,许多其他形式的传输系统是利用被传信
号的波形或电平来传送信息的,而这些参数又极易
受到传输途径中的噪声和衰耗的影响,
课 文
四川邮电职业技术学院 47
Text and translation
?因此选择数字传输系统在克服噪声环境方面有其
固有的优势,
课 文
四川邮电职业技术学院 48
Text and translation
?到目前为止,在这个讨论中,我们一直假定每个话
路各有一个编码器和解码器,前者是将幅度采样值
变成脉冲,而后者施行相反的变换,这种设置并非
必需,在实际运行的 PCM系统中,单一的编、译码
器为 24路,30路,甚至 120路所共用 (注, 在当代
PCM设备中,编、译码器系分路设备,即每个话路
各有一套,)
课 文
四川邮电职业技术学院 49
Text and translation
?一个高速的电子开关被用来将每一话路的模拟信
号依次地送往编、译码器,然后编、译码器再顺序
采样幅值并把这个幅值编成 8位码序列,
课 文
四川邮电职业技术学院 50
Text and translation
?因此从编译码器输出的信息就是一个分别对应于
话路 1,话路 2,等等的 8位码序列, 这种设备称为
时分复用,如图 1-2所示, 音域 8位码的码字序列按
时间顺序插接在一起,所以上面的复用原则称为码
字插接,
课 文
四川邮电职业技术学院 51
Text and translation
?接收端设置了分路设备,将 8位码序列分配到相应
的话路中,读者也许会问,分路设备怎么知道哪一
个 8位码组对应于第 1路、第 2路极其他各路呢?显
然这是很重要的,
课 文
四川邮电职业技术学院 52
Text and translation
?这个问题是很容易解决的,我们只要指定一个帧格
式,即在每一帧的开始放置一个被称作帧码或同步
字的独特的码序列以标志每帧的起始,
课 文
四川邮电职业技术学院 53
Text and translation
?而用分路设备的一个电路去检测同步字,从而就可
知道下一个 8位码组对应于话路 1.当最后一个话
路的码字收到之后,同步码字有再次出现,
课 文
四川邮电职业技术学院 54
While-reading Activities /
Key language points
?1.本篇课文涉及数字通信领域，题目为：,PCM
原理”,
四川邮电职业技术学院 55
While-reading Activities /
Key language points
?2,be dependent on 依靠，依赖，取决于,
?2?,performing是 perform的动名词,动名词虽为名词，
但 仍保留着动词的某些特征，例如它仍可带有动词宾语,
本句中的 these three functions就是 performing的宾语,
本课中这类例子很多，例如第四段中的最后一句中,
Consequently there is an inherent advantage for
overcoming noisy environments by choosing digital
transmission,
句中的 overcoming和 choosing都是动名词且带有自己
的动词宾语,
四川邮电职业技术学院 56
While-reading Activities /
Key language points
? 另有理论认为ＰＣＭ分为四过程，如下,
? The practical implementation of PCM makes use of other
processes,The processes are carried out in the order in which
they appear below,
Filtering
Sampling
Quantizing
Encoding
The filtering stage removes frequencies above the highest
signal frequency,These frequencies if not removed,may
cause problems when the signal is going through the stage of
sampling,Sampling of a waveform means determining
instantaneous amplitudes of a signal at fixed intervals,You
may have a problem in understanding what this sentence
means,but if you take time to look at Figure 7 on the following
Slide,you should be able to understand,
四川邮电职业技术学院 57
While-reading Activities /
Key language points
? 3,each value being represented这是一种独立分词结
构，用来表示一种伴随状态，作状语,可译成：“而每一
幅值被表示为”,独立分词结构在科技文章中相当常见，
例如,
There are many kinds of steel,each having its uses
in industry,
译为：“钢有许多种，在工业中每种都有它自己的用
途”,
独立分词结构还可以表示时间、原因或条件等，对主句
进行补充说明,例如表示原因,
The resistance being very high,the current in the
circuit was low,
译为,“由于电阻很高，故电路里的电流很小”,
四川邮电职业技术学院 58
While-reading Activities /
Key language points
?(3?).as a sequence of 8 binary digits句中的 as
意为“作为，表为，成为”,该短语可译成,“(表
为 )8位二进制码的序列”,
四川邮电职业技术学院 59
While-reading Activities /
Key language points
? 4,furthermore,adv.“而且；此
外”
Furthermore,these child-
raising families may raise other
people‘s children in addition to
their own,而且,这些抚养孩子的
家庭除了自己的孩子外也可以抚养
其他人家的孩子。
The house is too small,and
furthermore,it's too far from the
office,这座房子太小,而且离办公
地点也太远。
? 同义词, again,also,besides,by
the same token,in addition,
likewise,similarly,then,too,
? (4a) 脉冲流
? (4b),occupying是 occupy的
现在分词,
动词的 -ing形式可以作为名
词用，称为动名词，本课注释
(2)已对此作了介绍。动词的 -
ing形式亦可作形容词用 (称现
在分词 ).它一般修饰该动作的
发出者，而且它亦可带有自己
的宾语，例如本句中的,“a
voice channel occupying
the range 300Hz to 3.4kHz”,
该短语可译为,“占有 300Hz到
3.4kHz频率范围的话路”,
四川邮电职业技术学院 60
While-reading Activities /
Key language points
?5,n.(pl,maximums,-ma[-mE])最大量 ; 最大数 ;
最高点极点 ; 最高额,最大限度 【 数 】 极大 (值 );
最大 (值 )(发展的 )顶峰时期
reach a maximum 达到顶点
The excitement was at its maximum,
兴奋到极点。
The sound has reached its maximum,声音
达到最高音位。
?反义词,minimum
四川邮电职业技术学院 61
While-reading Activities /
Key language points
?6.本句中的几个词组可译为,
lightning strike 打雷
sparking of a car ignition system 汽车点
火系统的打火
thermal low-level noise 低电平的热噪声
四川邮电职业技术学院 62
While-reading Activities /
Key language points
? 7,known as the signal-
to-noise ratio 译为“称
为信号噪声比”,
? 7?,Be of + n,结构
Be of importance=be
important
be of the most interest
to= be most interesting
to
? 7a,compared to the
noise level 意为,“与噪声
电平相比”,
? 7b,this is not always
the case,实际情况并非
如此,
四川邮电职业技术学院 63
While-reading Activities /
Key language points
? 8,located in far outer space这
是一种分词短语结构,located是动
词的 -ed形式，称为过去分词，起
形容词的作用，在句中作定语,这
种分词往往用来修饰原来动词动作
的承受者,
例如,
The trees planted by me have
grown up.“我种的树已长大了,”
再例如,
Electromotive force results in
electrical pressure,compared
to water pressure.“电动势产生电
压，电压好比水压”
所以课文中的这一短语可译为,“位
于遥远太空中的 (卫星 )”,
? 8?,Alternative adj.随便一个的；
二者择一的 (三者或以上的选择用
choice)
The way was blocked,so we
went by an alternative road.这
条路被挡住了，因此我们走了另一
条路。
n,抉择；选择余地
I wanted to go out,but I had
no money,I had no alternative
but to staying at home.我想出去，
可是没钱；只能待在家里。
We have no alternative but
to go on.除了继续下去,我们没有
选择的余地。
There was no other
alternative but to fight till the
victory.除了战斗直到胜利,别无选
择。
四川邮电职业技术学院 64
While-reading Activities /
Key language points
? 9,By comparison 相比之下
? 9?,using the shape,or level of transmitted signal 为现在分词
短语结构，作伴随情况状语，可译为,“用传输信号的波形或电平 (来
传送信息 )”,
类似的例子还有,
The rockets rose hissing over the launching site.“火箭在发
射场的上空嘶嘶地上升,”
再例如,
They sat together,carefully studing the design of the
circuits,
,他们坐在一起仔细地研究着那些电路的设计,”
对课文中的这个句子，全句可译为,“相比之上，许多其他形式的
传输系统是利用被传信号的波形或电平来传送信息的，而这些参数
又极易受到传输途径中的噪声和衰耗的影响,”
四川邮电职业技术学院 65
While-reading Activities /
Key language points
? 10.consequently,adv.,
conj.所以，因此
Mr,Foster has never
been to China,
Consequently / Hence
he knows very little
about it."福斯特先生从
未去过中国,所以对中国了
解得很少。,
同义词,accordingly,
hence,as a result,
therefore,
10’,inherent advantage
固有的优势,
四川邮电职业技术学院 66
While-reading Activities /
Key language points
?11,So far in this discussion we have assumed that
each voice channel has a separate coder,the unit
that converts sampled amplitude values to a set of
pulses; and decoder,the unit that performs the
reverse operation,本句理解和翻译应注意结构的分
析,在宾语从句 that each voice channel has… 中
has带了两个并列的宾语 coder,decoder；且这两个成
分又分别带了非限制性定语从句,
四川邮电职业技术学院 67
While-reading Activities /
Key language points
? 12a,A high-speed
electronic switch, 一个
高速电子开关
? 14b,taken in turn 轮流
地，依次地
? 12c,Code 此处作动词，
编码,
四川邮电职业技术学院 68
While-reading Activities /
Key language points
四川邮电职业技术学院 69
While-reading Activities /
Key language points
?14,appropriate,adj.适合的 ; 适当的 ; 相称的
appropriate example适当的例子
appropriate manners适当的态度
Write in a style appropriate to your subject.
用与你的题目相称的体裁写。
Ordinary shoes are not appropriate to resist
the electricity.普通鞋不适于抗电击。
四川邮电职业技术学院 70
While-reading Activities /
Key language points
?15a,specifying a frame format 指定一个帧格
式
?15b,the frame code:帧码
?15c,synchronization word：同步字
?15d,so as to 以便，为了,
四川邮电职业技术学院 71
While-reading Activities /
Key language points
四川邮电职业技术学院 72
While-reading Activities /
Key language points
四川邮电职业技术学院 73
Text & Translation,
? 16,与本单元课题有关的电信术语或用语,
? 称作同步字的独特码序列
a unique sequence of pulses called synchronization word
? 涉及到第一, 第二及其它各路的序列
a sequence relating to channel 1,2 and so on
? 将抽样的幅值转换成一串脉冲的单元
the unit that converts sampled amplitude value to a set of pulses
? 由传输路由引入的衰减
the attenuation introduced by transmission path
? 被传信号的波形 the shape of transmitted signal
? 一条特定消息中的全部信息
the complete information about a particular message
? 由卫星上收到的信号 the signal received from a satellite
? 真实信号与噪声信号间的关系
relationship of the true signal to the noise signal
下 一 页
四川邮电职业技术学院 74
Text & Translation,
? 16,与本单元课题有关的电信术语或用语,
? 实现这三项功能的方案 the schemes for performing these 3 functions
? 一串幅值 a series of amplitude value
? 电话质量的话路 a speech channel of telephone quality
? 理论上最小取样频率 a minimum theoretical sampling frequency
? 汽车点火系统的打火 the sparking of a car ignition system
? 脉冲的, 有, 和, 无, the presence or absence of the pulse
? 时分多路复用器 Time Division Multiplexer
? 高速电子开关 a high-speed electronic switch
? 重复率为 64khz的脉冲流 the stream of the pulses with a repetition of 64 khz
上 一 页
四川邮电职业技术学院 75
Course Introductin----EST’s
features
? English for Science and Technology (EST),
? The Study focusing on EST began in 1950s,EST
has its own features in writing style,vocabulary,
grammar and rhetorical devices,
? Generally speaking,EST lays more emphasis on
scientificalness,logic,accuracy and strictness
instead of literary grace,Thus its writing often is
filled with nominalized phrases,passive voiced
sentences,non-restrictive attributive clauses and
postpositional determiners etc,
? Therefore,in understanding and translating the
material of EST,we lay more emphasis on
faithfulness,expressiveness and accurateness (信,
达,切 ) rather than faithfulness,expressiveness and
elegance( 信，达，雅,which advocated by Yanfu),
返 回
四川邮电职业技术学院 76
Course Introduction----EST’s
features
? Vocabulary Studying Tips
Get Familiar with certain lexicological devices
(word-formation);
Grasp the words? meaning in the concrete
registers (context,fields of science),
Read more related materials and do more
translation,Practice and repetition is the mother of
memory,
返 回
四川邮电职业技术学院 77
Course Introduction----
Vocabulary Studying Tips
? lexicological devices (word-formation);
(a),Compounding or composition ( about 27%),
raindrop pulse code modulation
(b),Derivation of affixation (about 17.5%)
Prefixation,decode synchronization
suffixation,modulation coder
(c),Conversion (about 10.5%),code
(d),Initialisms and acronyms （ about 9%),
PCM CCITT UNESCO NATO
(e),Blending (about 6%) TELEX
(f),Neoclassical formations (about 4%) psychedelic neuroliguistic
(g),Reduplication (about 0.5%) walkie-talkie
(h),Clipping (about 2%) phone lab
返 回
四川邮电职业技术学院 78
Course Introduction----EST’s
features
? Vocabulary Studying Tips
? Get Familiar with certain lexicological
devices;
? Grasp the words? meaning in the
concrete registers (context,fields of
science),
EYE,眼睛
inspection eye
hoisting eye
observing eye
television eye
flower eye
CELL 蜂窝，蜂房
The nucleus is the information center of
the cell,
细胞核是 细胞 的信息中枢。
He was imprisoned in a cell,
他被关在监狱的 单人小牢房 中。
In the center of the spacious workshop
stood a cell with packets of block
anodes,
在宽敞的车间中央有一个装有一组组阳极板
的 电解槽 。
When the ends of a copper wire are
joined to a device called an electric
cell a steady stream of electricity
flows through the wire,
当把一根铜丝的两端连接到一种叫做
电池 的电器上时，就会有稳定的电流
流过该铜丝。
A basic cellular system consists
of three parts,a mobile unit,a cell
site,and a MTSO,
一个蜂窝式系统基本上由三部分组成：
移动机，无线基站和电话交换就局。
Why one common word has so
many different scientific meanings?
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