What is a Signal Generator?
A signal generator is a device that provides electrical signals of various frequencies, waveforms, and output levels. When measuring the amplitude characteristics, frequency characteristics, transmission characteristics, and other electrical parameters of various telecommunication systems or telecommunication equipment, as well as measuring the characteristics and parameters of components, it is used as a test signal source or excitation source.
When testing, researching or adjusting electronic circuits and equipment, in order to measure some electrical parameters of the circuit, such as measuring frequency response, noise factor, and calibrating voltmeters, it is required to provide electrical signals that meet the specified technical conditions to simulate the excitation signal of the device under test. When the steady-state characteristic measurement of the system is required, a sinusoidal signal source with known amplitude and frequency should be used. When testing the transient characteristics of the system, it is necessary to use a rectangular pulse source with known leading-edge time, pulse width, and repetition period. And it is required that the parameters of the output signal of the signal source, such as frequency, waveform, output voltage, power, etc., can be accurately adjusted within a certain range, with good stability and output indication. Signal sources can be divided into four categories: sine wave signal generators, rectangular pulse signal generators, function signal generators, and random signal generators according to different output waveforms.
Types of Signal Generator
Sine signal generator
The sine signal is mainly used to measure the frequency characteristics, nonlinear distortion, gain, and sensitivity of circuits and systems. According to the frequency coverage, it is divided into the low-frequency signal generator, high-frequency signal generator, and microwave signal generator; according to the adjustable range and stability of output level, it is divided into the simple signal generator (ie signal source), standard signal generator (the output power can be accurately attenuated to below -100 decibel milliwatts), and power signal generator (output power is more than tens of milliwatts); according to the frequency change, it is divided into the tuned signal generator, sweep frequency signal generator, program-controlled signal generator type signal generator, and frequency synthesis type signal generator, etc.
The functional generator can generate some specific periodic time function waveform signal (mainly sine wave, square wave, triangle wave, sawtooth wave, pulse wave, etc.). The frequency range can be from the ultra-low frequency of a few millihertz or even a few microhertz up to tens of megahertz. In addition to being used for communication, instrumentation, and automatic control system testing, it is also widely used in other non-electrical measurement fields. The frequencies of these function generators can be electronically controlled, programmed, locked, and swept. In addition to working in the continuous wave state, the instrument can also work by key control, gate control, or triggering.
The pulse generator is a generator that produces rectangular pulses of adjustable width, amplitude, and repetition rate. It can be used to test the transient response of linear systems, or use analog signals to test the performance of radar, multiplexed, and other pulsed digital systems. The pulse generator is mainly composed of a master oscillator, a delay stage, a pulse forming stage, an output stage, and an attenuator. The main control oscillator is usually a circuit such as a multivibrator. Except for self-excited oscillation, it mainly works in a trigger mode. Usually, a pre-trigger pulse is output first after the external trigger signal is applied to trigger the oscilloscope and other observation instruments in advance, and then the main signal pulse is output after an adjustable delay time, the width of which can be adjusted. Some can output a pair of main pulses, and some can output two main pulses with different delays respectively.
Random signal generator
Random signal generators are divided into two categories: noise signal generators and pseudo-random signal generators. A completely random signal is white noise with a uniform spectrum within the operating frequency band. The intensity of the noise generator output must be known, usually expressed in decibels by which its output noise power exceeds the resistance thermal noise (called the excess noise ratio) or its noise temperature. When performing correlation function measurement with white noise signal, if the average measurement time is not long enough, there will be statistical errors, which can be solved by pseudo-random signal.
Difference Between Function Generator and Signal Generator
Due to the different structures, the frequencies of the generated signals are different, and the uses are different.
A function generator is a multi-waveform signal source. It can generate sine, square, triangle, sawtooth, and even arbitrary waveforms.
Application: The function generator has a wide frequency range and is widely used. It is an indispensable general-purpose signal source. It can be used in production testing, instrument maintenance, and laboratories, and is also widely used in other scientific and technological fields, such as medicine, education, chemistry, communications, geophysics, industrial control, military, and aerospace.
A signal generator is a device that can provide electrical signals of various frequencies, waveforms, and output levels, and has a wide range of applications in production practice and scientific and technological fields.
Application: The signal generator is used as a test signal source or excitation source when measuring the amplitude characteristics, frequency characteristics, transmission characteristics, and other electrical parameters of various telecommunication systems or telecommunication equipment, as well as when measuring the characteristics and parameters of components.
Application of Signal Generator
Signal generators, also known as signal sources or oscillators, have a wide range of applications in production practice and scientific and technological fields. Various waveforms can be represented by trigonometric equations. Function signal generators are widely used in circuit experiments and equipment testing. For example, in communications, broadcasting, and television systems, radio frequency (high frequency) transmission is required. The radiofrequency wave here is the carrier wave. To carry audio (low frequency), video signals, or pulse signals, an oscillator that can generate high frequency is required. In industry, agriculture, biomedicine, and other fields, such as high-frequency induction heating, smelting, quenching, ultrasonic diagnosis, nuclear magnetic resonance imaging, etc., oscillators with higher or lower power and higher or lower frequencies are required.