What Is a Noise Generator?
A noise generator is a device that generates noise.
Noise generators are mainly used to evaluate the performance of various devices and systems. Some devices can generate white noise or pink noise, and some are available as a function within function generators.
White noise is noise that has uniform intensity across the entire bandwidth from low to high frequencies on the frequency axis. When heard audibly, it sounds like “sir”.
Pink noise is noise whose components become smaller as the frequency increases. When heard audibly, it sounds like a “thud”, like the sound of strong rain or a waterfall. Noise generators are useful as sound and vibration sources for sound and vibration testing.
Uses of Noise Generators
1. Evaluation of Electronic Equipment
There are two types of noise generators: dedicated noise generators and noise generators provided as a function within function generators. The purpose of using either type is to evaluate the functionality and performance of devices.
The noise generator is used to generate white noise or pink noise that simulates the noise that occurs in the natural world, and to evaluate whether the device under test can maintain the desired functions and performance.
It is used for EMI (Electro Magnetic Interference) testing and BER (Bit Error Rate) testing to evaluate whether the data errors in a device are within a specified range. It is also used for data transfer tests on disc drives of various BD/DVD recorders.
2. Acoustic and Vibration Tests
Noise generators are used as sound and vibration sources for sound and vibration testing. By connecting the output of white noise to a loudspeaker, the acoustic, sound insulation, and sound absorption characteristics of a hall, etc. can be evaluated. They are also useful for vibration tests when connected to a shaker.
Principle of Noise Generators
Noise can be generated by using a noise generator, by using an electronic circuit such as a diode, or by using a programming language.
1. Using a Noise Generator
Noise generators are used for electromagnetic interference (EMI) tests and acoustic characteristic tests, etc. Noise generators and function generators have built-in noise generators. Select white noise, pink noise, etc. to output noise. The noise generator that comes with the synthesizer can also be used.
2. Generate Noise With an Electronic Circuit Such as a Diode
Use the broadband noise generated when a reverse voltage is applied to a zener diode, transistor, or operational amplifier. This is white noise, but it can also be generated by temperature-controlled resistors or gas discharge tubes. Pink noise is generated by inversely proportional power attenuation of the white noise to the frequency.
3. Using Programming Languages
This method uses a programming language such as C, Java, or Python. Noise is generated by software using random numbers.
Types of Noise Generators
There are various types of noise generators. Some types output noise ranging from a few KHz to the GHz band, and their output frequency can be set linearly.
The level of noise output can also be adjusted. In addition to interfaces that can be operated via a control panel on the device itself, some types can be controlled from a PC via Ethernet.
Other Information on Noise Generators
EMI Testing
EMI testing evaluates whether a device can continue to function correctly when subjected to the worst-case noise that could occur in the user’s environment. For example, in the case of a household appliance like a television, it is permissible for the interference to momentarily disrupt the image on the screen or lead to audio malfunctions.
When the transient noise is eliminated, the device must be able to return to its original state. In order to confirm such a situation, a noise generator is used to create a worst-case environmental condition and evaluate whether normal operation can be continued under such conditions.