# What is a Nyquist in Terms of Frequency?

• fsonnichsen
In summary, "Nyquist" is a term used in digital signal processing to measure frequency relative to the Nyquist frequency, which is dependent on the sample rate. It is similar to other dimensionless quantities used in physics, such as the Reynolds number. However, it is not common to refer to "a Nyquist" as a specific unit of measurement. The term may have originated from a draft of a textbook, but it is not a widely recognized term.
fsonnichsen
Can anyone tell me the definition of a "Nyquist" with respect to units of frequency? I didn't find it defined on the web. I presume it is some measure of cycles/sample or similar

Thanks
Fritz

fsonnichsen said:
Can anyone tell me the definition of a "Nyquist" with respect to units of frequency?
It isn't. But I can see that a creative author might decide he can use it as a measure of the ratio of two frequencies.

Do you have a reference to where you found it? Some topic dealing with sampling an analog signal, I presume.

This was in a draft of a textbook. I tend to agree with your premise that this is a "home spun" term.

Thanks
Fritz

In digital signal processing it is quite common to measure frequency relative to the Nyquist frequency (which depends on the sample rate of course). That is no different from other dimensionless quantities used in physics (e.g. Reynolds number).

But I've never seen the term "a Nyquist" used.

I can explain that Nyquist frequency is a term used in signal processing and digital signal sampling. It is defined as half of the sampling rate, or the maximum frequency that can be accurately represented in a digital system. This is based on the Nyquist-Shannon sampling theorem, which states that a signal must be sampled at a rate of at least twice its highest frequency component in order to accurately reconstruct the original signal. Therefore, the Nyquist frequency is a crucial factor in determining the sampling rate for digital systems to avoid signal distortion and aliasing. It is typically measured in hertz (Hz), the unit of frequency, and is an important concept in digital signal processing and communication systems. I hope this helps clarify the definition of Nyquist frequency for you.

## What is a Nyquist in Terms of Frequency?

A Nyquist is a term used in the field of signal processing to refer to the maximum frequency that can be accurately sampled or measured in a given system. It is named after the Swedish-American engineer Harry Nyquist.

## Why is Nyquist important in signal processing?

Nyquist is important because it helps determine the sampling rate needed to accurately represent a signal. If the Nyquist frequency is not taken into account, it can lead to aliasing, which is a distortion of the original signal.

## How is Nyquist related to the sampling theorem?

The Nyquist frequency is a key component of the sampling theorem, which states that in order to accurately represent a signal, the sampling rate must be at least twice the highest frequency present in the signal. This ensures that the original signal can be reconstructed without distortion.

## What happens if the Nyquist frequency is exceeded?

If the Nyquist frequency is exceeded, aliasing occurs, which means that higher frequency components of the signal are incorrectly represented as lower frequencies. This can result in distorted or inaccurate data.

## How is Nyquist used in real-world applications?

Nyquist is used in a variety of real-world applications, including audio and video processing, wireless communication, and medical imaging. It is a fundamental concept in signal processing and is crucial for accurately capturing and analyzing signals in these and many other fields.

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