电子信息专业英语复习

1 .3 Star P4

The star topology developed during the era when mainframes centrally controlled most computer communications. The voice switching world also employs a star topology when multiple remote switching nodes, each serving hundreds to even thousands of telephone subscribers, home-in on a large central switch. This network radiates in a star-like fashion from the central switch through the remote switches to user devices. The central node performs the communication switching and multiplexing functions in the star topology. Nodes communicate with each other through point-to-point or multipoint links radiating from the central node. The difference between this topology and the multipoint topology is that the central node only provides point-to-point connections between any edge nodes, on either a physical or logically switched basis.

星型拓扑结构发育在大型机集中控制大多数计算机通信的时代。语音切换领域在多个远程开关节时点也采用星型拓扑结构，每个服务于数百甚至数千名电话订阅者，安放在大型的中央交换机上。这个网络像星型一辐射，这个网络从中央交换节点通过远程交换到达用户设备。中央节点在星型拓扑结构中执行通信交换和多路复用功能。节点之间的连接，从中央节点通过点对点或多点链接辐射。这种拓扑结构和多点拓扑之间的区别是，中心节点只提供任在物理或逻辑上交换的基上的何边缘节点的点对点连接。

Figure 1 .5 shows a star topology, where Node A serves as the center of the star and Node B through E communicate via connections switched to and through the central Node A. An example of a star topology is many remote terminal locations, or clients, accessing a centralized server through the central node as illustrated in the figure. The physical star topology is widely used to connect devices to a central hub in LANs, and thus is often called a “hub and spoke” topology. The central hub may logically organize the physical star as a logical bus or ring as is commonly done in LAN wiring hubs. A key benefit of the physical star topology is superior network management of the physical interfaces. For example, if a single interface fails in a physical star topology, then the management system can readily disable it without affecting any other stations. Conversely, in a broadcast topology, a single defective switch can take down the entire shared medium network. As we shall see, many wide area networks also have a star topology, driven basically by the client-server computing paradigm.

图 1.5 显示星型拓扑结构，在节点A 作为星的中心而节点B 至 E 沟通通过连接切换到达和通过中央节点a。星型拓扑结构的一个例子是很多远程终端的地址或客户端，通过中心节点访问集中的服务器，如图所述。物理星型拓扑结构被广泛用于将设备连接到局域网的中央枢纽，因而通常被称为"中心和分支"的拓扑结构。中央集线器逻辑上可能把物理星型看成是一个逻辑总线或逻辑环，就好像局域网布线集线器一样。物理星型拓扑结构的关键好处是高级网络管理的物理接口。例如，如果在物理星型拓扑结构一个单一的接口没有成功，管理系统可以随时禁用它而不会影响任何其他接口的状态。相反，在广播的拓扑中，一个单一的缺陷开关可以取下整个共享介质网络。我们将会看到，很多的广域网络也有星型拓扑结构，基本上由客户端-服务器计算范式。

2 .

3 .1 Asynchronous and Synchronous Data Transmission P11

异步和同步数据传输

Asynchronous character transmission has no clock either in or associated with the transmitted digital data stream. Instead of a clock signal, start and stop bits delimit characters transmitted as a series of bits numbered 1 through 8 as illustrated in the example of Figure 2 .4 . There may be a variable amount of time bet ween characters. Analog modem communication

employs this method extensively. Here we simply explain the notion of baud rate, which is the number of discrete signals transmitted on the communication channel per unit time. Asynchronous character transmission usually operates at lower speeds ranging from 300 bps up to 28-kbps. Asynchronous interfaces include RS232C and D, as well as X .21.

异步字符传输并不需要时钟或与传输数字数据流关联。相反的时钟信号，启动和停止位分隔字符作为一系列的编号为1 至8，如图2.4 的示例中所示的位传输。可能有可变投注金额的时间之间的字符。模拟调制解调器通信广泛采用这种方法。在这里我们只是解释的概念是在每单位时间的通信信道上传输的离散信号数目的波特率。异步字符传输通常工作在较低的速度从300 个基点至28 kbps。异步接口包括RS232C 和D，以及作为级。

On the other hand, synchronous data transmission clocks the bits at a regular rate by a clocking signal either associated with, or derived from, the transmitted digital data stream. The motivation for synchronous signaling is to eliminate the extra time required to send the start and stop bits in asynchronous transmission. Since the start and stop bits are at least one unit time long, they comprise at least 20 percent of the line transmission rate. Therefore, in synchronous transmission, the sender and receiver must have a means to derive a clock within a certain frequency tolerance.

另一方面，同步数据传输钟表固定的频率上的位，由一个时钟信号关联，或来自传输数字数据的流。同步信号的动机是要消除发送开始和停止位在异步传输时所需的额外时间。由于至少一个单位时间长的启动和停止位，他们占线传输速率至少20%。因此，在同步传输中，发送者和接收者必须有一种手段来派生一个时钟在某些频率公差范围内。

3 .2 .6 Mobility 流动性P19

GSM is a cellular telephony system that supports mobility over a large area. Unlike cordless telephony systems, it provides location, roaming, and hand-over.

GSM 是一个蜂窝电话系统，在一个大面积内支持流动性。与无绳电话系统不同，它还能提供位置、漫游和移交等。

1 . Location Area 位置区域

The ability to locate a user is not supported in first-generation cellular systems. This means that when a mobile is called, the network has to broadcast the notification of this call in all the radio coverage. In GSM, however, location areas (LAs), which are groups of cells, are defined by the operator. The system is able to identify the LA in which the subscriber is located. This way, when a user receives a call, the notification (or paging) is only transmitted in this area. This is far more efficient, since the physical resource use is limited.

2 . Roaming 漫游

In particular, the GSM system has the capability of international roaming, or the ability to make and receive phone calls to and from other nations as if one had never left home. This is possible because bilateral agreements have been signed bet ween the different operators, to

allow GSM mobile clients to take advantage of GSM services with the same subscription when traveling to different countries , as if they had a subscription to the local network . To allow this, the SIM card contains a list of the networks with which a roaming agreement exists. When a user is “roaming” to a foreign country, the mobile phone automatically starts a search for a network stipulated on the SIM card list. The choice of a network is performed automatically, and if more than one network is given in the list, the choice is based on the order in which the operators appear. This order can be changed by the user. The home P LMN is the network in which the user has subscribed, while the visited PLMN often refers to the P LMN in which the user is roaming. When a user receives a call on a visited PLMN, the transfer of the call from the home PLMN to the visited PLMN is charged to the called user by his operator.

3 . Handover 移交

When the user is moving from one cell to the other during a call, the radio link between BTS 1 and the MS can be replaced by another link, bet ween BTS 2 and the MS. The continuity of the call can be performed in a seamless w ay for the user. This is called handover. With respect to dual-band telephones, one interesting feature is called the dual-band handover. It allows the user in an area covered both by the GSM-900 and by the DCS-1800 frequency bands, for instance, to be able to transfer automatically from one system to the other in the middle of a call.

10 .1 Signals P79

Signals are scalar-valued functions of one or more independent variables. Often for convenience, when the signals are one-dimensional, the independent variable is referred to as “time”. The independent variable may be continuous or discrete. Signals that are continuous in both amplitude and time (often referred to as continuous-time or analog signals) are the most commonly encountered in signal processing contexts. Discrete time signals are typically

associated with sampling of continuous-time signals. In a digital implementation of a signal processing system, quantization of signal amplitude is also required . Although not precisely correct in every context,discrete-time signal processing is often referred to as digital signal processing .Discrete-time signals, also referred to as sequences, are denoted by functions whose arguments are integers . For example, x (n) represents a sequence that is defined for all integer values of n and undefined for non-integer values of n . The notation x (n) refers to the discrete-time function x or to the value of the function x at a specific value of n .The distinction between these two will be obvious from the context .

Some sequences and classes of sequences play a particularly important role in discretetime signal processing . These are summarized below .

The unit sample sequence , denoted by δ( n) , is defined as

( 1)

The Eq .(1 ) plays a role similar to an impulse function in analog system analysis .

The unit step sequence , denoted by u( n) , is defined as Eq .(2 ) :

Exponential sequences of the form

play a role in discret e-time signal processing similar to the role played by exponential functions in continuous-time signal processing . Specifically, they are eigenfunction s of discrete-time linear syst ems and for tha t reason form the basis for transform analysis techniques . W hen | α| = 1, Eq . ( 3 ) takes the form of a complex exponential sequence typically expressed in the form

Because the variable n is an integer , complex exponential sequences separated by integer multiples of 2π in ω( frequency) are identical sequences, i .e .,

This fact forms the core of many of the important differences between the representation of discrete-time signals and systems and that of continuous-time signals and systems .

A general sinusoidal sequence can be expressed as

x( n) = A cos (ω 0 n+ Φ) ( 6)

where A is the amplitude , ω 0 the frequency, and Φ the phase . In contrast with continuous-time sinusoids, a discrete-time sinusoidal signal is not necessarily periodic and if it is , the

period is only when is an integer . In both continuous time and discrete time , the importance of sinusoidal signals lies in the facts that a broad class of signals can be represented as a linear combination of sinusoidal signals and that the response of linear time-invariant systems to a sinusoidal signal is sinusoidal with the same frequency and with a change in only the

amplitude and phase .

信号是一个独立或多个独立的变量的向量函数，为了方便，当信号是一维的时候，该变量是时间函数，这个独立的变量可能是连续的或是离散的。在幅度和时间上连续的信号通常被认为时间连续或模拟信号，这些都是在数字信号处理中常遇到的。离散时间信号与连续时间信号的抽样信号有着密切的联系。在一个数字处理系统的数字设备中，信号幅度的量化是必要的。尽管不是在每一个领域都是十分精确，离散时间信号处理通常被认为是数字信号处理过程。

离散时间信号，通常又被称为序列，用一些幅度为整数的函数来表征。例如X n 代表：对于给定一个特征值n,离散函数或函数值x,这两者之间的区别将在此中得到说明。

一些序列或一个序列数，在离散数字信号处理中充当特别的角色。它们概括如下：

序列δ n 扮演的角色如同冲击函数在模拟系统分析中的一样。

单位阶跃序列，用u n 来表征，被定义如下：

指数序列的形式的时候，被表达为：

由于变量n是一个整数，复杂的指数序列在ω 频率上以2π的整数倍被分解为唯一的指数

序列，例如：

这个事实构成了表征离散时间信号与系统和连续时间信号与系统不同特征的核心。一个规则的正弦曲线序列能被表达为：

x( n) = A cos (ω 0 n+ Φ) ( 6)

A为幅度，为频率，Φ为相位，与连续的正弦时间信号相比，离散时间正弦信号不必是周期性的，如果是，也只有在2π/是一个整数时，周期才为2π/，对于连续和离散时间信号，正弦信号的重要性在于这样一个事实：大量的信号族能被这样的正弦信号线性组合，同时正弦信号通过线性时不变系统的响应是一个正弦的，它们有相同的频率，仅仅只是在幅度和相位上有改变。

12 .3 Driving Forces in the Multimedia Communications Revolution P94

在多媒体通信革命的驱动力

Modern voice communications networks evolved around the turn of the twentieth century with a focus on creating universal service, namely, the ability to automatically connect any telephone user with any other telephone user without the need for operator assistance or intervention.

现代语音通信网络在20世纪发展的重点是建立普遍服务,即能自动连接任何电话用户与任何

其他电话用户不需要操作员协助或干预

This revolutionary goal defined as a series of technological problems that had to be solved

before the vision became reality, including the invention of the vacuum tube for amplification of telephone signals, mechanical switching to replace the operator consoles that were used in most localities, numbering plans to route calls, signaling systems to route calls, etc. The first transcontinental call in the United States was completed in 1915, thereby ushering in the “modern age of voice communications,” an age that has been developed and improved upon for the past 80 or so years.

这个革命的目标被称为一系列技术问题,必须解决在愿景成为现实之前,包括电子管的发明电话信号的放大,机械开关取代操作员控制台使用在大多数地方,编号计划路线电话,信号系统

路由电话,等。第一个横贯大陆的电话在美国于1915年完工,后来成为“现代语音通信的时代,一个时代已经开发和改进在过去的80年左右的时间。

We are now in the midst of another revolution in communications, one that holds the promise of providing ubiquitous service in multimedia communications. The vision for this revolution is to provide seamless, easy-to-use, high-quality, affordable multimedia communications between people and machines anywhere and anytime. There are three key aspects of the vision that characterize the changes that will occur in communications once this vision is achieved.

我们现在正处于又一次通信革命中，一个包含提供多媒体通信中无处不在的服务承诺。这场革命的美景是人机器在任何地方和任何时候都可以提供无缝、易用、高质量、可负担的多媒体通信。有三个关键方面的视觉特征的变化将发生在通信实现这个愿景。

(1) The basic currency of communications evolves from narrow-band voice telephony to seamlessly integrated, high-quality, broad-band transmission of multimedia signals.

(2) The basic access method changes from wireline connections to combinations of wired and wireless , including cable , fiber , cell sites, satellite, and even electrical power lines.

(3) The basic mode of communications expands from primarily involving people-to-people communications to including people-to-machine communications.

（1）通信革命的基本货币演变从窄带语音技术到无缝集成到高质量、再到宽频带多媒体信号传输。

（2）基本访问方法从有线连接变为组合的有线和无线，包括电缆、纤维、基站、卫星、以至电器的电源线。

（3）通信基本模式从主要涉及到包括人机通信的人民对人民通信扩展。

There are a number of forces that are driving this multimedia revolution, including:

· the evolution of communications networks and data networks into today’s modern Plain Old Telephone Service (POTS) network and packet (including the Internet) networks, with major forces driving these two networks into an integrated structure;

· the increasing availability of ( almost unlimited) bandwidth on demand in the office, the home , and eventually on the road, based on the proliferation of high- speed data modems, cable modems, hybrid fiber-coax systems, and, recently, a number of fixed wireless access systems; · the availability of ubiquitous access to the network via Local-Area Networks ( LAN’s ) , wireline, and wireless networks providing the promise of anywhere, anytime access;

·the ever increasing amount of memory and computation that can be brought to bear on virtually any communications or computing system-based on Moore’s law of doubling the communications and memory capacity of chips every 18 or so months;

· the proliferation of smart terminals , including sophisticated screen phones, digital telephones,

multimedia Personal Computers ( PC’s ) that handle a wide range of text , image, audio, and video signals, “network computers” and other low-cost Internet access terminals, and Personal Digital Assistants ( PDA’s ) of all types that are able to access and interact with the network via wired and wireless connections;

· the digitization of virtually all devices, including cameras, video capture devices, video play back devices , handwriting terminals, sound capture devices, etc., fueled by the rapid and widespread growth of digital signal-processing architectures and algorithm s, along with associated standards for plug-and-play as well as interconnection and communications between these digital devices . 有许多力量推动这种多媒体革命,包括:

?通信网络和数据网络的演变到今天的现代普通电话服务(锅)网络和包(包括互联网)网络,与大部队驾驶这两个网络集成的结构;

?(几乎无限的)带宽的增加可用性需求在办公室,家里,并最终在路上,基于高速度的扩散数据调制解调器电缆调制解调器,混合fiber-coax系统,,最近,一些固定无线接入系统;

?无处不在的可用性对网络的访问通过局域网(LAN)、有线、无线网络提供的承诺在任何地方,任何时候访问;

?不断增加数量的内存和计算,可以给任何通讯或计算系统的摩尔定律的芯片的通信和内存容量翻倍每18个月;

?智能终端的普及,包括复杂的屏幕手机,数字电话、多媒体个人电脑(PC)处理广泛的文本,图像,音频和视频信号,“计算机网络”和其他低成本的互联网接入终端,和个人数字助理(PDA)的所有类型能够访问和与网络交互通过有线和无线连接;

?几乎所有设备的数字化,包括摄像机、视频采集设备、视频回放设备,笔迹终端,声音捕捉设备,等等,由于增长迅速而普遍的数字信号处理体系结构和算法,以及相关的标准,即插即用,以及这些数字设备之间的互连和通信。

。

14 .1 Getting into Virtual Reality P107

进入虚拟现实

Users can represent themselves with an avatar . ( This word derives from the Sanskrit AVATARA , which means “descent”, according to the Encyclopedia Britannica . In Hinduism, avatar means the deity in human or animal form to counteract some particular evil in the world.) Representative of our selves , an avatar may or may not look like us; he could be a“digital clone”— hopefully this will never be too controversial or illegal — or the handsome creature from the fairy tales that never gets tired or ages . The avatars actions and behavior are driven by our actions; i.e., speech, movements, and emotions. This requires efficient real-time algorithms to process the raw speech signal, images, and video (from a single camera or multicameras) and to represent the extracted information in a compressed form.

用户可以代表自己的阿凡达。（这个词源于梵文个，这意味着"血统"，根据大英百科全书。在印度教，阿凡达指的神，在人类或动物的形式，以抵消一些特定的邪恶在世界。）可能会或可能不像我们;他可能是"数字克隆人"——希望这不会太有争议或非法——或英俊生物从童话故事，永远不会厌倦或年龄。化身行动和行为是由我们的行动; 驱动即，演讲、运动和情绪。这就需要高效的实时算法来处理原始语音信号、图像和视频（从单个摄像机或multicameras），并代表以压缩的形式提取的信息。

There is quite a bit of“traditional”signal processing in carrying such tasks (i.e., speech analysis/ synthesis, image and video segmentation, and motion estimation and tracking ,among

others ) . Such avatars live and move in a virtual synthetic or real world. The rendition of this world can be done using computer graphics techniques or photo realistic 3-D image spaces or a combination of the two (augmented reality).

还有相当多的"传统"的信号处理在执行此类任务(例如，语音分析/ 合成、图像和视频分割和运动估计和跟踪，除其他外的)。这种化身生活，在一个虚拟的合成或真实世界中移动。可以做的这个世界翻译使用计算机图形技术或现实三维图像空间或两个组合的图片（增强现实）。

Finally, different ways to interface with this new representation of physical world need to be devised. Stereoscopic displays, head mount devices, and complicated display systems, such as CAVE, provide means for such a visual interface. Life in a CAVE is a very rewarding experience and I encourage you to visit one nearest you!

最后，不同的方式与这个新的表示法的物理世界的接口需要设计。自由立体显示器顶装式设备，和复杂的显示系统，如洞穴，为这种可视化的界面提供了手段。在一个山洞里的生活是非常有益的体验，我鼓励你去离你最近的一个！

This is an exciting research topic that is expected to keep generating a lot of interest and exciting applications. In fact, MPEG-4, the recent multimedia compression standard, addresses interactivity, as well as encoding of synthetic scenes and facial animation parameters which can be used to animate a 3-D facial modal.

All these exciting aspects of immersive virtual reality are addressed in the six articles of this well-thought our special issue.

这是一个令人兴奋的研究课题，预计将保持大量生成的兴趣和令人兴奋的应用程序。事实上，MPEG-4，最近的多媒体压缩标准，解决了交互性，以及编码合成的场景和面部动画参数可以用来对三维人脸模型进行动画处理。所有这些令人兴奋的沉浸式虚拟现实所述考虑周全的这六条我们特殊的问题。

23 .9 Time-saving Examples P199

Probably the most important benefit attributable to using algorithms, kernels, and development tools that are all integrated and standardized is improved time to market. To illustrate this, the following table compares the development time required to create a Universal Port application using traditional development methods and the Express DSP real-time software technology described above. Programmers designed this application to handle voice, data, and fax in a single system.

可能最重要的好处归因于使用算法、玉米粒与所有集成和标准化的开发工具是加快产品上市时间。为了说明这一点下, 表创建使用传统的开发方法和上文所述的表达DSP 实时软件技术的通用端口应用程序所需的开发时间的比较。程序员设计该应用程序可以在单个系统中处理声音、数据和传真。

The comparison is between designing the code completely from scratch and

using an integrated algorithm/ tools/ operating system framework. The result in this example is a 60 % reduction in development time. In addition, the target system overhead needed to support the standard is substantially lower. Using the standards based framework, the application incurs less than a 1% increase in execution cycles and less than a 1 % increase each in program and data memory . Additionally, intangible benefits include:

设计完全从零开始的代码和使用集成的算法是比较/ 工具/ 经营系统框架。在此示例中的结果是60%减少开发时间。此外，需要支持标准的目标系统开销是极大地降低。基于框架

的使用的标准，应用招少于执行周期增加了1%，小于1%增加每个程序和数据的内存中。此外，无形的好处包括︰

· improved determinism through standard code Part IV Electronics 199

· reliable optimized code

· easier debugging during integration and field-testing

It is clear that the age of do-it-yourself DSP software development is over . The rise of:

· standard algorithms

· DSP r un-time components

· open integrated development tools and

· support from an extensive third-party network

Allow DSP software engineers to innovate as quickly and creatively as their hardware colleagues . The results for DSP product development OEMs are:

· exceedingly fast time to market

· creatively advanced products

· the ability to capture market through software differentiation

·通过标准代码部分四电子199

·改进的决定论可靠的优化的代码

·容易在集成过程中调试和实地测试

很显然，自己动手的DSP 软件开发的时代已经结束。兴起︰

·标准算法

·DSP 研发非时间组件

·打开集成的开发工具和

·从广泛的第三方网络支持允许DSP 软件工程师

允许DSP 软件工程师，以创新为快速和创造性硬件的同事一样。Oem 是DSP 产品发展的结果︰

·非常快的时间市场

·创造性地先进的产品

·捕获市场通过软件分化的能力

24 .2 Choosing a Processor P203

Digital signal processors are in many ways similar to general purpose processors . One of the main differences between the two is that the DSP is typically optimized to process certain signal processing functions very fast, like filtering and Fast Fourier Transforms ( FFT ) .Many steps in these functions are executed with single cycle instructions in a DSP . Engineers designed DSPs with scalability in mind. Many real-time signal processing functions decompose their processing over many processors in order to gain a significant improvement in processing time. This feature can operate either temporally or spatially ( Figure 24 .3) . Processors that house these functions need to have fast inter-processor communication. In the DSP processor , this fast communication is usually accomplished using high-speed I/ O ports and shared memory . Figure 24 .3 Spatial and Temporal Decomposition .

数字信号处理器在很多方面类似于通用处理器。两者的主要区别之一是DSP 通常优化，速度非常快，加工某些信号处理功能像过滤和快速傅里叶变换(FFT)。在这些函数中的许多步骤与在DSP 中的单周期指令执行。工程师们设计了Dsp 考虑可缩放性。许多的实时信号处理功能分解他们处理许多处理器相比，为了获得重大改善的处理时间。此功能可操作时间

上或空间上(图24.3)。房子这些功能的处理器需要有快速处理器间通信。Dsp 数字信号处理器，在这快速的通信通常是使用高速我/ O 端口和共享的内存。图24.3 时空分解。

There are an increasingly larger number of options available to system designers for a general-purpose DSP. These include:

有越来越多的选项可用的通用dsp 系统设计师。这些措施包括︰

Application Specific Integrated Circuits ( ASICs ) : These devices can function as DSP

co-processors but are not very flexible for many general-purpose signal processing needs .

RISC Processors: The extremely fast clock speed for these devices allows them to perform well in certain DSP applications. Scalability and other real-time (predict ability ) issues still remain for these devices . DSPs are specifically made to handle real-time deterministic applications .

Field Programmable Gate Arrays ( FPGA ) : These devices are very fast and can do

certain DSP functions very quickly . However, they are also more difficult to develop in comparison to a DSP where a simple program can do the same function .

Host Signal Processing: This area is becoming a more popular area in the DSP arena .

Host signal processing generally refers to executing DSP algorithms on a PC ( referred to as the host) . Many of the lower-end multimedia applications function in this way, but PC-based DSP still lags behind a true DSP solution for high-performance DSP applications .

应用专用集成电路(Asic): 这些设备可以作为DSP 的协处理器，但不是很灵活的许多通用信号处理的需要。RISC 处理器︰速度极快的时钟速度为这些设备允许他们好在某些DSP 应用程序中执行。可扩展性和其他实时（预测能力）问题仍为这些设备。Dsp 是专门作出了处理实时确定性应用程序。现场可编程门阵列(FPGA): 这些设备速度非常快，很快能完成某些DSP功能。然而，他们也更难于形成与DSP 一个简单的程序可以在那里做相同的功能。

主机信号处理︰这一领域变得更受欢迎的地区，在DSP 舞台上。主机信号处理一般是指在个人计算机（称为主机）上执行DSP 算法。很多低端多媒体应用程序功能的这种方式，但基于PC 的DSP 仍落后于一个真正的DSP 解决方案为高性能DSP 的应用程序。

Because of the complexity of today’s signal processing applications and the need to upgrade often, a programmable device such as a DSP has become an at tractive alternative rather than a customized hardware solution .

由于今天的信号处理应用程序和需要经常升级的复杂性，如DSP 的可编程器件已成为牵引的替代，而不是定制的硬件解决方案。

P205

Another factor in processor choice is the required memory for an application . Typically,in RISC processors, the required memory to run an application goes up . This is because it takes more RISC instructions to execute a particular algorithm than a conventional CISC

processor . In some cases, the increase can be dramatic . All of the research, benchmarking,and prototyping should be used to determine memory requirements for a particular application . There is always the possibility of trading performance for memory, and memory can be optimized at the cost of application performance . Since DSP algorithms involve performing tight loops of operations over many data points, if just these small kernels are optimized, the performance improvement is substantial .

在处理器选择的另一个因素是为应用程序所需的内存。通常情况下，在RISC 处理器中，所需的内存来运行应用程序就会上升。这是因为它需要更多的RISC 指令来执行特定的算法比

传统的CISC 处理器。在某些情况下，增加可以是戏剧性的。所有的研究、基准测试和原型应该用于确定特定的应用程序的内存要求。有始终是有可能的交易为内存，性能和内存可以优化应用程序的性能代价。由于DSP 算法涉及执行行动的紧凑循环在许多数据点，如果只是这些小的内核进行了优化，性能的改善是实质性的。