电子信息工程专业英语考试要点总结(4)

needed ,bring the signals back out to the analog world through the

digital-to-analog converter.

数字信号是模拟信号的数值表示。在数字世界里，对这些信号进

行处理可能会更容易、成本更低。在现实世界中我们可以通过“模数

转换”将信号转换为数字信号，然后对信号进行处理；如果需要的话，

用“数模转换器”将信号转换回到模拟世界中去。

8.Keep in mind that the distinction between DSPs and other

microprocessors is not always a clear line .For instance ,look at how Intel

describes the MMX technology addition to its Pentium processor : "Intel

engineers have added 57 powerful new instructions specifically designed

to manipulate and process video ， audio and graphical data

efficiently .These instructions are oriented to the highly parallel ,

repetitive sequences often found in multimedia operations . "

别忘了:DSPs 和其他微处理器的界限并不是很清晰。例如，让我

们看一看inte 是如何描述其奔腾处理器新增的MMX 技术的：“为了

高效操作和处理视频、音频和图形数据，intel 工程师新增了57 条功

能强大的指令。这些指令面向的是多媒体操作中经常出现的、高度并

行和重复的程序。”

9.In practical application , these are certainly many other factors to

consider when evaluating analog versus digital filters ,or analog versus

digital signal processing in general . Most modern signal processing

8、systems use a combination of analog and digital techniques in order to

accomplish the desired function and take advantage of the best of both the

analog and the digital world .

在实际应用中，在评价模拟滤波器和数字滤波器（或模拟信号处理和数字信号处理）的时候，坑定还要考虑许多其他因素。为了实现期望的功能和充分利用两种技术各自的优势，多数现代信号处理系统都采用了模拟技术和数字技术相结合的方式。

10.Audiophiles demand the utmost sound quality , and all that factors are

treated as secondary .If you had to describe the mindest in the world , it

would be : overkill . Rather than just matching the abilities of the

human ear ,these systems are designed to exceed the limits of hearing .

It's the only way to be sure that the reproduced music is pristine .

高保真音响爱好者对声音质量的要求极高，所有其他因素都被视为次要的。假如要用一个词来描述这种心理活动的话，那就是“过分”。高保真音响系统不是设计得刚好满足人类的听觉需求，而是超越了人类的听觉极限，这是唯一能够确保再现音乐无任何失真的办法。

11.Then the sample are processed in groups of 1152 (about 26 msec

worth). Each group is first passed through 32 digital filters to get 32

frequency bands . At the same time the input is fed into a psychoacoustic

model in order to determine the masked frequencies .Next each of the 32

frequency bands is further transformed to provide a finer spectral

resolution .

在这之后，样本以1152(约26ms)为一组进行处理。每组样本首先通过32 个数字滤波器，从而得到32 个频带。同时，输入信号进入心理声学模型以决定被屏蔽的频率。下一步，32 频带中的每个频带 中的每个频率进一步变换得到更好的频谱分辨率。