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Name: Imaboung
Status: Student
Grade: 9-12
Location: GA
Country: United States
Date: April 2008


Question:
What is electrical noise? Are there different types of electrical noise?



Replies:
Electrical noise is any kind of electrical energy that you do not want. For example, if you tune your radio to a place between two broadcasting stations, you may hear some static or bleed through from nearby stations. You may consider what you hear to be electrical noise. Here is an example that may be more subtle. If you are listening to music off your computer or media player, and there is a silent passage in the music or between songs, you may hear some background noise in the form of a hiss - this noise is inherent in electrical devices. Good electronic products have components selected to minimize this noise. The electrical content you want is called signal. Electronic devices are often rated with something called a signal to noise ratio. The higher the number, the better. Hope this helps.

Bob Froehlich


Hi Imaobong,

The most broad definition of electronic noise, is the presence of unwanted electrical signals that make it more difficult to detect or process the actual signals one is interested in. An example of this is an ordinary audio amplifier, such as that in cassette player. Very weak signals are picked up from the moving tape, and fed to the amplifier, which increases their strength sufficiently that these signals can now drive a speaker or earphones.

With an amplifier such as this, electrical noise (or "noise" for short) can result unwanted noise in the speaker of earphones. This "noise" can come from inside or outside the amplifier. Many devices such as fluorescent lights, computers, and many others, generate and transmit unwanted signals. These signals may be picked up by the above amplifier, and amplified together with the music from the tape. The result can be a buzzing or other objectionable noise you hear.

In a television, the same sort of unwanted random transmitted signals can cause speckles to appear and dance around on the TV screen, messing up the picture.

Sometimes the components that are used to make the amplifier circuit create electrical noise that can be heard in the speaker or earphones. Components like transistors, used in an amplifier, are never "perfect" and themselves can generate small amounts of random signals ("noise") together with the signals they are supposed to be amplifying. This can often be heard as a low level hissing noise in the speakers together with the music.

Electrical noise, therefore is simply any unwanted electrical signals that may be picked up from other equipment that is unintentionally radiating (transmitting) them, or the unwanted signals can be generated within the equipment by less than perfect components. We call them "noise", because the effect is similar to how audio noise prevents you from clearly hearing a sound or music you are trying to hear.

Regards,

Bob Wilson


Most generally, noise is any unwanted fluctuation in a reading. For example, a circuit may have an intended signal -- say a voltage change -- but when you actually measure the voltage, you may see fluctuations in the voltage. The fluctuations are called 'noise'. If you graphed your voltage, instead of a smooth straight line like you intend, it might be bumpy and bounce above and below the intended level.

You may also see a term called 'signal-to-noise', which is a measure of how strong your signal is compared to how strong the noise is. If your signal is 100 times stronger than your noise, the chances are good you will be able to detect the signal. If your noise is just as strong as your signal, or stronger, then you may have more trouble detecting the signal.

Hope this helps,
Burr Zimmerman



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