It is said that the oscilloscope is an electronic visualization instrument or apparatus, for the graphic representations of electrical signals that could even vary in time.
And it is that these devices are widely used in signal electronics, and usually works in conjunction with a spectrum analyzer since the values of the electrical signals are presented as coordinates on a medium-sized screen, in which generally the X-axis is horizontal and represents the times. The Y-axis is vertical and is responsible for representing the tensions.
What is an oscilloscope
As a concept of an oscilloscope, we can say that it is a measuring instrument for electronics, which in turn represents a graph of amplitude on the vertical axis and time on the horizontal axis.
Students widely use it, designers, engineers in the field of electronics, as it is often complemented by a multimeter, a power supply, and a function generator or arbitrary, lately, with the explosion of devices with radio frequency technologies such as WiFi or Bluetooth, the workbench is complemented by a spectrum analyzer.
How an oscilloscope works
For DC voltages, the voltage level (at offset = 0) is read directly from the distance to the zero lines. In the example on the right, we assume that 2 V / DIV are set. In this case, the magnitude of the measured voltage is 8 V. For alternating voltages, the peak voltage (Us) and the peak-to-peak voltage (Uss), as well as their frequency, can be read off from the curve signal. In the example, again assuming a setting of 2 V / DIV, the peak voltage is 5 V and USS 10 V. The frequency results from the time course of a complete oscillation after the conversion f = 1 / T. In our example, a swing, assuming a set time base of 50 μs / DIV, runs over five grid units of the time axis, i.e., 50 μs x 5 = 250 μs. 1/250 μs = 4 kHz.
Without triggering, the signal would go through the screen all the time, and one would not get a stagnant signal image needed for accurate evaluation. The triggering must establish a temporal and phase reference between the input signal and the time-deflection signal. To do this, the trigger generator samples the measuring signal to an adjustable level (trigger level) either on the rising, falling, or both slopes (Slopes) according to the operator’s instructions. It compares the detected trigger level with the setting. Suppose he detects the signal under the given conditions, the outputs a trigger pulse, and starts the vibration of the time deviation. The trigger source can be both the measuring signal, a signal from an external source, and the mains frequency.
The time sweep is the constant horizontal deflection of the beam across the image width. The time base used is a deflection generator whose frequency can be set in a defined manner. Usually, a sawtooth signal is used here. All measuring signal impulses arriving during its rise time are displayed on the screen. The start of the sawtooth signal occurs for each pass through the trigger pulse. The lower the frequency of the sawtooth, the more pulses of the waveform are displayed.
The vertical deflection ensures the vertical positioning of the beam in proportional dependence on the voltage level of the input signal. For this purpose, it is adapted to the deflection possibilities of the oscilloscope via a defined voltage divider (attenuator) via a vertical amplifier. Here also, the DC / AC input coupling is defined.
AC / DC coupling
While the DC coupling allows all signals to pass, superimposed DC components are separated during AC coupling. Also, additional filters are available for the trigger coupling, which filter out specific frequency components in the trigger signal or only pass them through.
Let’s start by knowing that the applications or functions of an oscilloscope are very diverse since it is an instrument to general-purpose apparatus, or also as devices for specific purposes.
As the oscilloscope achieves a wide variety of applications or uses, which can range from the medina to the field of industry, of course going through a variety of scientific occupations that stand out from biology to physics.
That is why we have decided that we will explain a small list of the general functions of oscilloscopes:
- In medicine: It is presented as an electrocardiograph or electroencephalograph and works to find the measurements of venous and arterial depression, measurement of the respiratory rhythm, and finally, as an electro-graph, that is, it measures the electrical activity of the nervous tissues.
- In radio communications: It works as spectrum analyzers, frequency meters, modulation meters, and finally, as tests or demonstration of transmission lines.
- For electronic instrumentations: They serve for measurements of amplitude, phase, frequency, and distortions of electrical signals, as well as as-as a plotter of curves, that is, characterization of various devices.
- As navigation: They work like radar systems, sonar systems, signaling devices, guidance systems, and finally, as simulation systems.
- In physics: In physics, they are presented as durations of short events, that is, pulses from nanoseconds to milliseconds, monitoring of nuclear activities, characterization of materials, and also as experiments for spectroscopy.
- In industries: They work as test and measurement systems, monitoring, and testing for quality controls.
- For services: In the field of service, they work or services for the repair of electronic equipment, and also for automotive electronic tunings.
Types of oscilloscope
Now, the oscilloscopes are divided into two types, analog and digital, that is why we will briefly explain the two types of oscilloscopes:
- Analog oscilloscope: In this type of oscilloscope, the voltage to be measured is applied to the vertical deflection plates of the oscillating device of a cathode ray duct, an amplifier with high input and gain impedances that can be adjustable must be used. , while a sawtooth-shaped tension is applied to the horizontal deflection plates.
- Digital oscilloscope: The analog oscilloscopes are currently being changed by digital oscilloscopes, for many reasons, counting first of all the facilities to transfer all the measurements to any LCD screen or personal computer, since in these oscilloscopes, like its name indicates, previously the signal is digitized by an analog-digital convert.