How to Calculate Frequency from Oscilloscope

An oscilloscope is a device used to view the voltage of an electrical component in the form of waves on a screen. It consists of a screen, input ports, and several controls. Oscilloscopes can be either analog or digital.

Most current oscilloscopes will provide you with the readings for voltage and frequency. They usually have other statistical information such as standard deviation and mean.

That said, if your budget oscilloscope does not have these features, you could manually calculate the frequency by yourself.

So, let’s learn how to calculate the frequency from the oscilloscope.

Oscilloscopes and Frequency

Essentially, an oscilloscope visualizes electronic signals (or voltage) passing through a component (such as a wire). It does so by turning the electronic signals into a graph on its display screen, where the voltage is displayed on the vertical axis, and the time is measured on the horizontal axis of the graph.

Most oscilloscopes can display both AC (alternating current) and DC (direct current) waveforms.
The time and voltage units on most oscilloscopes can be adjusted from seconds per division (s/div) to nanoseconds per division (ns/div) and from volts per division (V/div) to microvolts per division (μV/div), respectively.

Measured in hertz, frequency is the number of times oscillating waves pass a certain point on the graph every unit of time (so, for example, five waves per second).

Finding out the frequency of a voltage waveform can be useful for myriad reasons. The most common of them being that, when the frequency of the waveform of a component’s voltage is measured, it can tell us whether the component is working as it should be or if its voltage needs to be fixed.

Calculating Frequency Using an Oscilloscope

Let’s go through the entire process.

Enlarging Display Area

Start by making sure the signal area on your oscilloscope’s display is enlarged.

Measuring Time

Then, measure the time value using the horizontal scale of your oscilloscope, and also by counting the number of divisions (horizontally) between the two ends of a wave, along the Center Horizontal Graticule Line.

In simpler words, this means to count the number of divisions between the peak points of the waves on the waveform of your signal (or a part of the signal’s waveform whose frequency you wish to calculate).

Multiplying

The next step is to multiply this number of horizontal divisions by the time/div value to find the signal’s “period”. And the period of a wave is the amount of time it takes for the wave to complete a full cycle.

Using Formula

Now that you have all your elements, you can use a simple formula to find out the frequency of the waves. This formula will have you divide the value 1 by the period of the wave (or waves) in order to calculate the frequency. So, the formula for this would be: frequency = 1/the period of a wave.

Conclusion

As mentioned before, finding out the frequency of a waveform is only a matter of navigating on a screen in the case of most modern oscilloscopes.

However, if needed, this frequency can also be worked out manually using the few steps mentioned above.

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