What Is Frequency Oscilloscope?

Oscilloscope, also known as O-scope or simply just scope informally, is an incredibly useful tool for engineers and regular people alike.

It is used to display the varying signal voltages of an electric signal and how it changes over time. An oscilloscope’s bandwidth is what represents the frequency of it.

So when we are talking about the frequency of an oscilloscope, we are actually talking about its bandwidth. To learn what is frequency oscilloscope and what certain level frequencies can do to your oscilloscope reading, check out the next section.

What Is Frequency and How Is It Represented?

The frequency of an oscilloscope indicates the level of frequency you can calculate with it. It is represented by bandwidth.

Bandwidth is often considered to be the oscilloscope’s single most critical feature, and that is justified. Measured in Hertz, the bandwidth of an oscilloscope is the span of frequencies it can precisely calculate.

If you do not have enough bandwidth, your signal’s amplitude will be incorrect & your waveform details may get lost.

On the contrary, if you have too much bandwidth, you can detect unnecessary noise, thereby providing you with an incorrect calculation.

Why is that you may ask? Well, to answer, think of your oscilloscope as a low pass filter, which only allows frequencies up to a certain limit to pass.

Low pass filters allow the signals to pass in maximum possible amplitude before the frequency of the signal reaches the higher end of the frequencies that the filter allows to pass.

Then, a filter attenuates the signals that pass through them right to the point when the amplitude of the signal is dampened to nothing.

When the signal reaches three decibels upon attenuating, you have reached the cutoff threshold of your oscilloscope’s bandwidth specification.

Say, your oscilloscope has a bandwidth of 200 mega Hertz, and you know now that it means that the filter of your oscilloscope has a cutoff frequency of 200 mega Hertz.

Why should this knowledge matter to you? Read the next sections for an answer to that.

The Consequence of Too Much Frequency

You can capture noise from the environment with your oscilloscope. When doing so, the oscilloscope will add noise to the signal when it is being filtered, processed, and then digitized. This noise addition takes place at all frequencies.

So, with your 200 mega Hertz oscilloscope, it will show noise up to 200 mega Hertz only; on the other hand, if your oscilloscope has 30 GigaHertz bandwidth, it will add noise to the measurement all the way through its entire range of frequency regardless of the frequency of the signal.Thus, your signal will have a lot of noise.

Another reason you would not want to get too high of bandwidth is that they cost a lot more. Basically, the higher the bandwidth of the oscilloscope, the greater the price will be.

What if there are possibilities that you might need higher bandwidth in the future? Get an oscilloscope with the feature that lets you upgrade the bandwidth through purchasing a software license.

That way, your oscilloscope will not become obsolete, and you can still get usage out of it without needing to purchase an entirely new one.


The Consequence of Too Little Frequency

The Consequence of Too Little Frequency

If you attempt to measure a signal with a higher frequency than the oscilloscope’s cutoff frequency, you will either get a distorted and attenuated version of the signal or not get much of a signal at all.It isn’t even a good idea to measure a signal with as high a frequency as the highest scope of bandwidth.

If you try to measure a 200 mega Hertz signal with a 200 mega Hertz oscilloscope, you will not get the best representation of the signal as the filter will have already started to distort the input due to reaching the maximum frequency.

Although there are many essential features of an oscilloscope that you will need to check before you pick one for your measurements, obviously, bandwidth is the most important spec you will need to review before any other. Without a good bandwidth range, you will not get an accurate and clean measurement at all.


Now that you understand why frequency and bandwidth are so important and how they work, I hope your purchase decision for an oscilloscope has become a little bit easier as you know what to look for. Thanks for reading!

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