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Measurement Equipments
A signal generator is a device widely used in the electronics industry for many years. Although the initial models were quite basic compared to today's, the technology has evolved tremendously, providing a wide range of features and improved performance. The first signal generators were analog and were quite limited. With the digital age, all generators have evolved and are now capable of performing much more complex functions. Now we will look at the main types of signal generators.
This category covers various types of devices, such as function generators, arbitrary function generators (AFG), and arbitrary waveform generators (AWG). In addition, there are more specific generators, such as those for audio signal, radio frequency and vector signals.
Function generators are devices designed to produce a limited but precise set of periodic waveforms at specific frequencies. In turn, a signal generator can be analog (traditional) or digital.
A traditional, or analog, signal generator works by using electronic circuits that generate varying voltages to create different waveforms. Here's a basic description of how it works:
In summary, an analog signal generator produces tunable waveforms by manipulating analog electronic circuits that control the frequency, amplitude, and shape of the generated signal.
The most modern models employ a technology known as direct digital synthesis (DDS), allowing waveforms to be generated at exact frequencies with a rapid response to frequency changes during generation.
A DDS (Direct Digital Synthesis) signal generator is an electronic device used to produce periodic waveforms with exceptional precision in terms of frequency and phase. It uses a digital technique to generate signals, in contrast to traditional analog methods. Instead of employing complex analog circuitry, a DDS generator uses a stable frequency oscillator and a digital-to-analog converter (DAC) to create output signals.
The key to the operation of a DDS generator is a digital phase counter, which produces a sequence of values that are used to determine the signal amplitude at each sampling point. These values are fed to a lookup table, which stores the amplitude values of the desired waveform. The output of the DAC is fed these amplitude values to generate the final waveform.
The main advantage of a DDS generator is its ability to generate waveforms with high precision and frequency stability, as well as to quickly switch between different frequencies. This makes it ideal for applications where a variable frequency signal is required, such as in stimulus response testing, signal modulation, or in audio and RF (radio frequency) synthesis.
These generators typically have limited memory, storing only a few standard periodic waveforms such as sine, square, pulse, ramp, and sweep. However, depending on the device, more or fewer waveform options may be offered. They are cost-effective tools for applications such as stimulus response testing, filter characterization, and clock source simulation, which require exclusively periodic waveforms.
Arbitrary Function Generators (AFG) share similarities with standard digital function generators powered by DDS, but with one key additional feature: the ability to store and use user-defined waveforms. This involves having a dedicated internal memory space to store these custom waveforms, allowing the user to define a specific waveform, save it to the AFG's memory and then generate it using the Direct Digital Synthesis (DDS) technique. In addition to these custom waveforms, AFGs also include predefined sets of waveforms stored in their internal memory, which can also be generated using DDS. Therefore, AFGs are highly valuable tools when working on applications similar to those requiring standard function generators, but with the advantage of being able to define more unique waveforms than those provided by the manufacturer. It is important to verify that the device's available memory is sufficient to store user-defined waveforms before purchasing.
Arbitrary Waveform Generators (AWGs) have the ability to generate both standard waveforms and complex, custom user-defined waveforms. Some AWGs can also combine and link waveforms to effectively produce sequences of waveforms. To generate complex or sequenced waveforms, AWGs require a considerable amount of internal memory to store these waveforms. Therefore, when selecting an AWG, it is important to ensure that it has sufficient memory capacity for the specific waveforms of your application. In addition to the expanded memory capacity, AWGs also use a different clock scheme compared to standard function generators or AFGs that employ DDS. The clock scheme in an AWG sends points in the exact order in which they are stored in memory, meaning they cannot change the output frequency instantaneously.
Analog wave generators have distinct advantages and disadvantages compared to DDS, AFG, and AWG.
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The bandwidth of a signal generator refers to the frequency range within which the generator can produce signals with acceptable amplitude and minimal distortion. In other words, it is the range of frequencies that the generator can generate accurately and faithfully. In exact terms, the maximum limit that defines this bandwidth is the point where the signal attenuation is 3dB.
For example, if a signal generator has a bandwidth of 0 Hz to 100 MHz, it means that it can generate signals with frequencies from 0 Hz to 100 MHz with acceptable quality and minimal distortion.
The larger the bandwidth, the higher the frequency you can generate sinusoidally with less distortion, but also the shorter the rise time of the signal. This is an especially important parameter when generating square wave signals and pulse trains.
Bandwidth is an important specification to consider when selecting a signal generator, especially if you are working with applications that require specific frequencies within a certain range. A wider bandwidth allows the generator to cover a wider range of frequencies, making it more versatile in different applications.
Bit resolution in signal generators refers to the precision with which the device can represent the amplitude of the signal. It is similar to the concept of bit resolution in digital systems, where it refers to the amount of information that can be stored or processed.
In a signal generator, the bit resolution determines the number of amplitude levels it can generate. For example, a signal generator with 8-bit resolution can represent the signal amplitude using 256 different levels (2^8 = 256), while a 12-bit generator can represent the amplitude with 4096 levels (2^12 = 4096).
Higher bit resolution generally translates into greater accuracy in waveform generation as it allows a wider range of amplitude levels to be represented and therefore greater fidelity in signal reproduction. This is especially important for applications that require high precision in the generated waveform, such as high-fidelity testing or communications system design.
In summary, bit resolution in signal generators is a key factor influencing the accuracy and quality of the generated signal, and higher resolution typically translates into better fidelity in waveform reproduction.
When evaluating a signal generator, it is important to consider these parameters and how they align with the specific requirements of your application.
An RF (Radio Frequency) generator is a device used to generate radio frequency signals, which are electromagnetic signals used in a wide variety of applications, such as wireless communications, radio and television equipment testing, radio frequency measurements, scientific research and development of electronic devices, among others.
These generators are capable of producing RF signals with frequencies ranging from a few kilohertz (kHz) to several gigahertz (GHz), depending on the design and specifications of the device. They can generate different types of waveforms, such as sine, square, triangular, and modulated waveforms, depending on the application needs.
RF generators can range in complexity, from basic devices that generate simple signals to more advanced generators that offer a wide range of functions and features, such as modulation, attenuation, frequency sweep, and remote control.
In summary, an RF generator is an essential component in many applications involving radio frequency signals, providing the ability to generate accurate and controlled signals for a variety of purposes.
A vector generator is an advanced version of an RF generator that can not only generate radio frequency signals, but can also modulate and manipulate them in more sophisticated ways. These generators are primarily used in wireless communications applications, such as testing mobile devices, wireless networking equipment, and radar systems.
Here are some distinguishing features of vector generators:
In summary, vector generators are powerful and versatile tools in the field of wireless communications, providing advanced capabilities to generate, modulate and analyze complex RF signals for a variety of applications.
A pink noise generator is a device that produces a noise signal whose power spectral density is inversely proportional to frequency. This means that as the frequency increases, the power density decreases. The name "pink" comes from the analogy with the visible light spectrum, where the color pink has a similar energy distribution.
Some important features of a pink noise generator include:
In summary, a pink noise generator is a valuable tool in test and measurement, as well as in the design and analysis of audio and communications systems, providing a controlled source of noise with a specific power distribution in the frequency domain.
An audio generator is a device designed to produce audio signals, which are acoustic signals in the frequency range audible to humans, typically from a few hertz (Hz) to several kilohertz (kHz). These generators are commonly used in a variety of applications, including audio equipment testing, sound system calibration, acoustic research, and music production, among others. In many cases the generators seen above can be used as audio generators.
Here are some important features and applications of audio generators:
In summary, audio generators are versatile and essential tools in a variety of sound and audio-related applications, providing a controlled source of audio signals for testing, calibration, research and music production.
