《信号发生器的功能是什么-中英文翻译.doc》由会员分享，可在线阅读，更多相关《信号发生器的功能是什么-中英文翻译.doc（9页珍藏版）》请在taowenge.com淘文阁网|工程机械CAD图纸|机械工程制图|CAD装配图下载|SolidWorks_CaTia_CAD_UG_PROE_设计图分享下载上搜索。
1、What Are the Functions of a Signal Generator?When an engineer, scientist or technician needs a thorough, reliable way to analyze an electronic system, he might reach for a signal generator. It produces an oscillating signal with precisely controlled frequency and amplitude characteristics, and is an
2、 indispensable tool for testing different types of audio, video, radio and other types of broadcast equipment. DescriptionA signal generator is a common piece of electronic test equipment. It is a convenient source of time-varying electrical signals with known waveform, frequency and amplitude. It o
3、ffers several waveforms of good quality with accurate and stable frequency.FeaturesA signal generator has controls to set frequency range, frequency fine tune and amplitude. It will have either a waveform selector switch or have simultaneous outputs for a few different waveforms. The ones most frequ
4、ently offered are sine, triangle and a rectangular pulse. Some generators will have a rising or falling saw tooth waveform. A digital generator may have very large selections of pre-programmed waveforms. A more sophisticated model has amplitude and frequency modulation, possibly with a built-in modu
5、lation oscillator. If it offers modulation, there may be an input for an external modulation signal.PurposeOne of the main uses of signal generator is to send a signal into a circuit to test it. A technician looks at the signal at different points in the circuit with an oscilloscope, spectrum analyz
6、er or other equipment. If the signal is distorted, attenuated or missing entirely, this will tell her what the circuit is doing. It is used to test systems of equipment, injecting a pure signal into a radio transmitter, for example. Analyzing the received signal can tell a lot about the quality of b
7、oth transmission and reception.A signal generator can drive mechanical equipment, like a shaker. A shaker is used to vibrate something, like a piece of equipment under test. If the signal generator drives the shaker with a 20 hertz sine wave and the equipment falls apart, the designers might have to
8、 rework it to be sturdier.TypesAn audio signal generator covers the frequency range of hearing and is meant for work on audio equipment. Usually, it has a frequency range greater than the audio range, such as 1 hertz to 100 kilohertz, to test the circuits past their normal range. A radio frequency s
9、ignal generator operates to 10 gigahertz, depending on the model. A microwave signal generator produces signals up to 70 gigahertz or higher. In 2009, many signal generators have gone digital-they produce the waveforms digitally and synthesize the frequency from a quartz crystal standard. Other sign
10、al generators use analog circuits-the frequency is based on an adjustable RC network, and the waveforms are shaped using active networks. Some signal generators produce a special-purpose signal, like a test pattern for aligning a television.ConsiderationsSince a signal generator can start at about $
11、100 and go to tens of thousands, it makes sense to know what you need before buying one. A radio-frequency generator would be overkill if you mainly work with audio equipment. If you do a lot of testing on broadcast equipment, a good digital signal generator will pay for itself in time savings. Like
12、wise, if you need extreme frequency stability and precision, a digital model will work better for you.Types of Signal GeneratorsEngineers, technicians and scientists use many kinds of signal generators in their work. Audio signal generators are the most common type, used for testing sound equipment
13、and to run scientific experiments. Communications and broadcast technicians use radio frequency (RF) generators for radio and television. Telephone and radar engineers use microwave signal generators. And digital engineers use logic generators to develop computer circuits. For complex applications,
14、such as digital television, technicians may use different kinds of signal generators at the same timeAudioA technician who works on sound gear will have an audio-frequency signal generator on his bench. Though the range of human hearing generally runs 20 to 20,000 cycles per second, the signal gener
15、ator will have a wider range of frequencies, to test equipment to its limits. It has a selection of fixed waveforms, including sine, triangle, square and saw tooth. The best signal generators have waveforms of very high purity to look for harmonic distortion.Noise generators produce a random, static
16、-like signal covering the entire audio bandwidth. White noise gives equal probability to all frequencies in its range. Pink noise has equal energy per octave; its white noise with low-pass filtering. These are used to test the frequency response of audio circuits and room acoustics.RadioRadio signal
17、 generators cover a higher frequency range than audio, to hundreds of megahertz or more. Theyre used to test radio broadcast equipment. Generating radio frequencies with precision is more difficult than audio, so these signal generators are more expensive.Since radio broadcasts use modulation, a sig
18、nal generator will produce two signals, the carrier frequency and a modulating signal. The signal generator will have amplitude and frequency modulators built in, to test different kinds of broadcast gear.MicrowaveThese signal generators produce frequencies into tens of gigahertz. Theyre used to tes
19、t communications equipment and radar. As the frequencies are even higher than for radio, and since the equipment is more specialized, its more expensive.LogicEngineers who build computer-related equipment need logic signal generators. These produce a variety of high-frequency pulses modulated by dat
20、a. Since data is specific to an application, the signal generators relate to external data sources.ArbitraryA traditional signal generator produces a fixed set of waveforms, such as sine and saw tooth. An arbitrary signal generator lets you create and program a wave shape, which is then produced at
21、the frequency you set. These generators are digital in nature, creating the wave shapes from a data table.Principles of Signal GeneratorsA signal generator is an electronic instrument that generates repeating voltage waveforms.An ideal signal generator can simply be modeled as a voltage source as sh
22、own in Fig1.Fig1 the model of ideal signal generatorWhere Vs(t) is a specified function of time. A practical signal generator is modeled as an ideal signal generator connected to a series source resistance (output resistance) Rs as shown in Fig 1 (b). The terminal voltage, v(t), is the output of the
23、 signal generator and depends on the terminal current, i(t), and Rs. Vs(t) can be, in general, a sine wave, a square wave, a triangular wave or a pulse train. The first three are characterized by three parameters: frequency (or period), amplitude, and DC (Offset) value. The pulse train is associated
24、 with frequency, amplitude and pulse duration. These parameters can be set to any value in the operation range of the signal generator, using the external controls. In general, amplitude ranges of signal generators vary from 10 mV to 20V, and frequency ranges vary from 1Hz to 40 MHz. This means sign
25、als for which the amplitude and frequency can be set to any value in these ranges can be generated using these signal generators. Signal generators usually produce more than one type of signals. Different signal types can be obtained by proper connection and/or switching. A simplified block diagram
26、of a sine and square wave generator is given in Fig.2. Fig2 Block diagram of a sine and square wave generatorA sine wave oscillator is the heart of the signal generator. It generates a sine wave of fixed amplitude and adjustable frequency, which is set by the external frequency control. This signal
27、is fed to both attenuator I and squarer. The signal amplitude is set to the desired value determined by external controls, by attenuator I. The output of attenuator I is a sine wave with desired amplitude and frequency.The squarer generates a square wave of fixed amplitude and at the same frequency
28、with the sine wave. The output of the squarer is fed to attenuator II which acts similar to attenuator I. The output is the square wave with amplitude and frequency which are determined externally.信号发生器的功能是什么？当工程师，科学家或技术人员需要一个彻底的，可靠的方法来分析的电子系统，他可能需要一个信号发生器。信号发生器能产生一个振荡信号精确控制的频率和幅度特性的振荡信号，在用于测试不同类型的音
29、频、视频，无线和其他类型的广播设备中，信号发生器是不可缺少的工具。描述电子测试仪器的信号发生器是一种常见的测试工具。在已知的波形，频率和幅度的随时间变化的电信号测试中，这是一个方便的来源，它提供了多种品质好，准确和稳定频率的波形。特点对信号发生器的控制，来设定频率范围、幅度等，这将需要一个波形选择器开关，或同时为几个不同的波形的输出，最经常输出的是正弦波，三角波和矩形脉冲。一些信号发生器也会产生上升沿或下降沿锯齿波形。对于可编程的波形，数字发生器有非常大的选择范围，一个更复杂的模型，需要对幅度和频率进行调制，可能有一个内置的调制振荡器。如果它进行调制，还有可能是一个外部的调制信号的输入端。目的
30、信号发生器的主要用途之一就是对一个电路发送一个信号，以测试它。一名技术员在观察示波器，频谱分析仪或其它设备的电路中不同点处的信号时。如果信号失真，衰减或完全丢失，这会告诉她这个电路现在在干什么。过去它用来测试设备的系统，就是用一个无线电发射机发送一个纯粹的信号，例如，分析接收到的信号时，可以知道很多发送和接收的一些特点。信号发生器可以驱动的机械设备，例如振动器，像一种测试设备一样可以用来筛选东西。如果20赫兹正弦波信号发生器来驱动振动筛选器，设备将不会工作，设计师可能需要返工，以使它更加坚固。类型一种音频信号发生器听觉的频率覆盖范围是指对音频设备的工作范围。一般它具有的频率范围是大于音频1赫兹
31、至100千赫兹范围，通过其正常范围用于测试电路。无线频率信号发生器运行至10千兆赫，这取决于在模型上。微波信号发生器产生的信号高达70 GHz或更高。在2009年，许多信号发生器已经达到数字化，他们生产的数字波形频率取决于石英晶体标准。其它信号发生器使用模拟电路-频率是根据一个可调的RC网络，和波形的形状是使用主动网络。某些信号发生器能产生一个特殊用途的信号，通过测试模式来调整电视的工作。注意事项由于信号发生器的价格可在100美元左右开始，到数以万计，再买它之前，你需要知道你要买一个什么类型的信号发生器。如果你主要使用音频设备，射频发生器会矫枉过正。如果对一个广播设备你做了很多的测试，良好的数
32、字信号发生器将支付本身在节省时间。同样如果您需要极高的频率稳定度和精度，数字模型将更好地为你服务。信号发生器的种类工程师，技术人员和科学家使用多种信号发生器工作。音频信号发生器，是用于测试声音设备和运行科学实验最常见的类型。对于广播和电视，通信和广播技术使用无线电频率（RF）发生器。电话和雷达工程师使用微波信号发生器。数字工程师使用逻辑发信号发生器来开发计算机电路。对于复杂的应用，例如数字电视，技术人员可能会在同一时间使用不同的信号发生器。音频音响设备的技术人员将需要声频信号发生器。虽然人类的听觉范围的一般运行每秒20至20,000个周期内，在测试设备中，信号发生器将具有更广泛的范围内的频率，
33、可以达到它的极限。它有一个固定波形的选择，包括正弦波、三角波、方波和锯齿波。对于在观察波形的谐波失真时，最好的信号发生器具有非常高的纯度波形。噪声信号发生器能产生一个随机的，静态的能覆盖整个音频带宽的信号。白噪声给出了相同的概率在其范围内的所有频率。粉红噪声每倍频程具有相同的能量，它是白噪声，低通滤波。这些用于测试音频电路的频率响应和室内声学。无线电无线电信号发生器覆盖比更高的频率范围的音频，到几百兆赫或以上。他们已经习惯了内测试无线电广播设备。产生无线电频率精度比音频比较困难，所以这些信号发生器都比较昂贵。由于广播使用调制，信号发生器将产生两个信号，载波频率和调制信号。信号发生器将具有内置的
34、幅度和频率调制器，用于测试不同种广播齿轮的微波。这些信号发生器产生到几十千兆赫的频率，他们用来测试通信设备和雷达。由于频率甚至高于无线电广播，并且由于设备更专业，所以它更昂贵。逻辑建立计算机相关设备的工程师需要逻辑信号源。这些通过数据产生的各种高频调制的脉冲是特定于应用程序，信号发生器涉及到外部数据源。其他传统的信号发生器产生一组固定的波形，如正弦波和锯齿波。任意信号发生器允许您创建和编写波形的形状，然后再在您所设定的频率进行编程。从数据表中创建的波形形状来看，这些发生器在本质上是数字的。信号发生器的原理信号发生器是一个能够产生重复电压波形的电子仪器。作为电压源，如在图1所示，一个理想的信号发
35、生器可以简单地进行建模。图1 模型的理想信号发生器其中，VS（t）是指定的时间函数。一种实用的信号发生器被建模为一个连接到一系列源电阻（输出阻抗）卢比，如在图1（b）所示理想信号发生器。v（t）为信号发生器输出的终端电压，取决于终端上的电流i（t）和Rs。在一般情况下，VS（t）可以是一个正弦波，方波，三角波或脉冲串。前三个的特点是由三个参数：频率（或周期），振幅和DC（偏移）值。相关的频率，振幅和脉冲持续时间的脉冲串。这些参数可以被设置为使用外部控制信号发生器的操作范围中的任何值。在一般情况下，信号发生器的幅度范围变化从10 mV至20V，而从1Hz到40 MHz的频率范围内变化。这意味着可
36、以使用这些信号发生器产生的信号的振幅和频率可以被设置为在上述范围内的任何值。信号发生器通常产生一个以上的类型的信号，不同的信号类型，可以通过以下方式获得正确的连接。一个正弦波和方波发生器的简化框图，如图2所示。图2 方框图的正弦波和方波发生器正弦波振荡器是信号发生器的心脏。它会产生一个幅度固定和频率可调的正弦波，这是由外部频率控制。该信号被馈送到两个衰减器I和平方器。该信号的幅度值，按照自己需要的值由外部控制的。通过衰减器I，他所输出的是一个按照自己所需的幅度和频率所定的是一个正弦波。平方器能在正弦波相同的频率下能产生一个固定幅度的方波，平方器的输出被馈送到第二衰减器的作用类似衰减器I，它输出的是方波额外的幅度和频率。