A digital oscilloscope measures the change of voltage over time. It converts an analogue electrical signal into a digital waveform that’s displayed on a screen.
For beginners, a digital oscilloscope can look daunting especially with the many buttons that dot the control panel.
There are some advanced and complex operations that you only learn with experience. But getting started with basic signal analysis is easy.
Here are some beginner-friendly tips on how to use a digital oscilloscope.
1. Understand the Oscilloscope
Before you start, it’s important to get a basic understanding of what the oscilloscope does and what it measures.
The most important part of the oscilloscope is the screen where the waveform appears.
The horizontal scale (x-axis) is for time while the vertical scale (y-axis) is for voltage. The time scale shows you how the voltage changes over time.
On the time scale, the oscilloscope can measure frequency, rise time and duty cycle among other time characteristics.
On the vertical scale, the oscilloscope measures the max and min voltage values, amplitude and average voltage.
In most cases, the oscilloscope will calculate these aspects automatically and display them on a screen. You don’t have to do any pen and paper calculations.
Most digital oscilloscopes can also carry out advanced operations including integration, square root and fast Fourier transform (FFT).
Next to the screen is the control panel with several buttons.
The buttons allow you to adjust the x or y axis, start and stop measurements, set a trigger (the signal for the oscilloscope to begin measuring), take a still image of the wave form and save an image to a storage device.
You can also use the buttons to carry out various mathematical operations and adjust various settings such as attenuation.
2. Setting up a Digital Oscilloscope
Your oscilloscope likely came with a probe. If it did not, look for one that’s compatible with the oscilloscope.
The probe carries the signal from your circuit to the digital oscilloscope.
To measure a signal, insert the probe into the first channel of your oscilloscope and set the attenuation switch to 10X for the best accuracy. If you are measuring low frequencies, you can leave the probe set at 1X attenuation.
Turn on the oscilloscope and wait for it to boot up.
The first thing you’ll see on the screen are the vertical and horizontal scales and a flat line across the screen. You’ll also see some basic setting on the right side.
To get started, turn on channel 1 (and turn off other channels), select trigger source to channel 1, choose DC coupling, choose rising edge trigger type, set the trigger mode to auto and select the attenuation that matches the attenuation on your probe (1X or 10X).
These settings are ideal for most basic operations. With experience, you’ll be able to select additional settings like AC coupling, logic triggering and so on.
3. Testing the Probe
Before you connect the probe to a circuit, you may want to test it first using the frequency generator on the probe.
Connect the tip of the probe to the signal output and the ground clip to the ground conductor. Check the screen for a square waveform.
Play around with the buttons for adjusting the horizontal and vertical scale and see what happens to the wave.
For instance, you can decrease time to display a single wave period or zoom out to see how the periods repeat.
If the wave keeps shaking or dancing, rotate the trigger position button, making sure you don’t set the trigger higher than the highest peak on the waveform.
You may also need to adjust the probe if the square wave has slanted horizontal lines. Turn the screw head on the probe until you see straight lines.
4. Measuring a Signal
After testing the probe and getting an idea of what the different buttons do, try measuring the signal from a real circuit.
Connect the grounding clip to a grounding point on the circuit and then use the tip of the probe to test different parts of the circuit.
Most probes come with extra attachments such as hooks or clip for attaching to a circuit.
Check the signal waveform on the screen and adjust the horizontal and vertical scales depending on the resulting wave and the level of detail you want.
Use edge triggering to stabilise the wave.
Note: If you have a multi-channel oscilloscope, you can measure two or more different signals at the same time. All the waveforms will appear on the screen. Remember to turn on the channels that you’ve connected probe to.
5. Taking Measurements
The oscilloscope will display various automatic measurements on the screen including amplitude, frequency and period.
Most oscilloscopes also have built-in mathematical functions for doing advanced operations. Play around with all these functions and settings and you’ll be a pro in no time.
It also helps to consult the user manual for specific advice regarding using a particular oscilloscope.
Most oscilloscopes have an internal memory, which allows you to save screenshots of waveforms. Most also allow you to save to an external device, usually a USB thumb drive.
An oscilloscope with USB output allows you to save more images and transfer them to other devices such as a computer or printer.