How Does an Oscilloscope Work?

Last updated on October 15th, 2020 at 04:43 am

An oscilloscope is an electronic device that automatically uses the signals which are fed into it with the help of probes which are hooked up to an electric circuit. It is a scientific instrument or a piece of medical monitoring equipment.

The Oscilloscopes can be used for looking at any and all kinds of signals that change in circuits over time. It can also be used to locate faults in broken televisions, radios, and all kinds of similar equipment. The probes of typical oscilloscope let you feed in the electric currents via coaxial cables.

Plug in the transducer that converts one kind of energy to another. For example, a microphone can be used to study the sound signals with the help of best digital oscilloscope; you can use a thermocouple to study the changes in the temperature or a piezoelectric transducer in order to study the vibrations such as heartbeats.

How an oscilloscope works

A traditional oscilloscope works in the same way as a traditional television that was based on cathode ray tube. The other name of the oscilloscope is cathode ray oscilloscopes or CROs. In a television, the electron beams are used to scan back and forth across the screen which is coated on the back using special chemicals called phosphors. Every time when the beam hits the screen, the phosphors light up.

With no time, the electron beams sweep across the entire screen, and the picture visible to your eyes is built. This is done repeatedly so that a moving picture is seen instead of a still image. Similarly, in an oscilloscope the electron beams work in the same way, the only difference being they draw a graph instead of a moving picture.

The electrical signals which are fed into the x and y connections effectively become the x and y values on your on-screen chart. As there is a one-to-one correspondence between the two values or points, a traditional oscilloscope is known as an analog device.

 

Modern digital oscilloscopes are divided into three classes: digital storage oscilloscopes (DSO), digital phosphor oscilloscopes (DPO), and sampling oscilloscopes. All the three classes have vertical, horizontal, acquisition, and triggering systems.

The vertical system is the first entry point for the signals coming directly from the probe. The amplitude of the incoming signal to the voltage range of the subsequent circuits is optimized. There are usually two knobs or controls in this section which help to control the vertical position and volts/division. The volts/division knob will allow you to set the vertical scale on the oscilloscope screen.

When you rotate the knob clockwise, the scale will be decreased, and when it is rotated counter-clockwise, the scale will increase. A smaller scale or fewer volts per division indicates that you are more zoomed in to the waveform. The position knob on the controls focuses on the vertical offset of the waveform on the oscilloscope screen. Here, when the knob is rotated clockwise, the waves will move down, and when the knob is rotated counter-clockwise, the waves will move up the display. The position knob can be used to offset part of a waveform of the oscilloscope screen.

The acquisition system encompasses the time-base (or horizontal) elements plus the actual digitizing and storage elements. It samples the signal voltage, acquiring the numerous data points to display on the screen. In a best digital oscilloscope, the horizontal system contains the sample clock, which gives each voltage sample a precise time (horizontal) coordinate.

The seconds per division knob rotates in order to increase or decrease the horizontal scale. The rotation on the clockwise direction will decrease the number of seconds per division and vice versa. The position knob will move the waveform to the right or left side of the display in order to adjust the horizontal offset. The horizontal system can be used to adjust how many periods of waveform you want to see.

The trigger system detects a user-specified condition in the form of an incoming signal stream and applies it as a time reference in the waveform record. The event that meets all the trigger criteria is displayed on the screen similar to the waveform data preceding or following the event. The trigger system ensures that a stable and consistent waveform will be displayed on the screen. The trigger system looks for the voltage thresholds, pulse widths, logic combinations (on multiple inputs), and many other conditions to qualify an acquisition. The trigger section is entirely devoted to stabilizing and focusing the oscilloscope. The trigger tells and signals the scope what parts of the signal to trigger on and start measuring. A poorly triggered waveform will produce seizure inducing sweeping waves.

 

There are a series of buttons and screen menus that make up the entire trigger system. The main purpose of the system is to trigger the source and mode.

Here is the review that the team of this website did about the Best Oscilloscope for Audio.

In automatic trigger mode, the best digital oscilloscope attempts to draw your waveform even if it doesn’t trigger. The normal mode of the oscilloscope will only trigger and draw the waveform what is seen by the specified trigger. The single mode of the oscilloscope will look for the specified trigger and when the trigger is seen it will draw the waveform and then stop.