龙岩学院毕业设计夕卜文翻译(1) 可以存储更多个期望波形周期。这很有用，因为减少了 “断点”数。 “断点是指波形的最后存储器位置，在这个位置之后AWG必须折回到存储器的开始位置，才能连续产生输出信号。由于转换时发生的误差是不可避免的，所以 希望减少端点数量。(2) 可以存储更多的波形细节。在复杂波形的脉冲边沿处和波形过渡处存 在着高频信息。在这些快速转变区域，很难采用与简单、可预测正弦波形一样的 插值方法。为了真实再现一个复杂信号，现有的波形存储容量必须用于存储更多 的过渡和振荡波形，而不是更多的信号周期。今天的AWG技术水平提供了 8兆的存储深度。某些顶级型号AWG同时提供大存储 深度和高采样率。这些仪器可以存储和重现复杂的射频波形，甚至包括用于网络 设备物理层测试的伪随机数据流。同样，这些AWG能够产生非常短暂的数字脉冲 和暂态波形。Signal SourcesThe Complete Measurement SystemAn acquisition instrumentusually an oscilloscope or logic analyseris probably the first thing that comes to mind when you think about making electronic measurements. But these tools can only make a measurement when they arc able to acquire a signale of some kind. And these are many instances in which no such signal is available unless it is externally provided.A strain gauge amplifier , for example , does not produce signals ;it merely increases the power of the signals it receives from a sensor. Similarly , a multiplexer on a digital address bus docs not originate signals ; it directs signal traffic from counters registers , and other elements . But inevitably it becomes necessary to test the amplifier or multiplexer before it is connected to the circuit that feeds it. In order to use an acquisition instrument to measure the behavior of such devices ,you must provide a stimulus signal at the input.Td cite another exemple, engineers must characterize their emerging designs to ensure that the new hardware meets design specifications across the full range of operation and beyond . This is known as margin or limit testing . It is a measurement task that requires a complete solution ; one that can generate signals as well as make measurements .The toolset for digital design characterization differs from its counterpart in analog / mixed signal design ,but both must include stimulus instruments and acquisition instruments. The signal source, or signal generator , is the stimulus source that pairs with an acquisition instrument to create the two elements of a complete measurement solution.What is a Signal Source?A signal source is nothing less than the cornerstone of almost any instrumentation setup used in hardware design, debug, or evaluation projects . It is a key engineering tool. It is an essential troubleshooting aid for the technician. It is a surrogate for an automotive ignition pulse, a heart pacemaker, or a guided missiles gyro output. Second only to the ubiquitous DMM, signal sources are perhaps the most universal class of electronic test instruments .Unless you are working with a purely DC circuit, your circuit is likely to require some kind of AC stimulus signal as you evaluate components, functional blocks, and subsystems. The waveform from the signal source emulates a signal coming in from the outside world , such as a sensor output. Similarly, it can be used as a stand-in fbr waveforms that will appear in as-yet-unavailable parts of the circuit design.Interestingly, the signal sources job is not simply to provide an idealwavefbrm. Often the instrumcnet must add known , repeatable amounts and types of distortion(or enors) to the signal it delivers. This characteristic is one of the signal sources strongest virtues, since il is often impossible to create predictable distortion exactly when and where its needed using only the circuit itself. The response of the unit-under-test(UUT) in the presence of these distorted signals reveals its abillity to handle stresses that fall outside the normal performance envelope.A stimulus signal may take the form of a low-distortion sine wave, a streame of logic pulses , a high-frequency radio carrier wave , a mobile telephone transmission , and many other formats . Traditionally , the task of producing these diverse waveforms has been filled by separate, dedicated signal sources, from ultra-pure audio sinc-wavc generators to multi-GHz RF signal generators. While there are many commercial solutions, the user must often custom-design or modify a signal source for the project at hand. It can be very difficult to design an instrumentation-quality signal generator, and of course, the time spent designing ancillary test equipment is a costly distraction from the project itself.Fortunately, digital sampling technology and signal processing techniques have brought us a solution that answers almost any kind of signal generation need with just one type of instrument-the arbitrary generator.Types of Digital Signal SourcesBroadly divided into arbitrary waveform generators(AWG), arbitrary function generators(AFG), and data or pattern generators(DG), digital signal sources span the whole range of signal-producing needs.Each of these types has its unique strengths:AWG: Whether you want a data stream shaped by a precise Lorentzian pulse for disk-drive characterization, or a complex modulated RF signal to test a GSM-or CDMA-bascd telephone handset, the AWG can produce any waveform you can imagine. You can use a variety of met