ALL ABOUT OSCILLOSCOPE
The oscilloscope is a measuring device that allows us to see changes in electrical voltage that depend on time. We can say oscilloscope is basically a graphic display device. Oscilloscopes, are an important tool in the armoury of the electronics engineer or tester. The oscilloscope shows information about time interval, rise time, and distortion of the formed signal.
A basic oscilloscope consists of four different systems :
- Vertical system
- Horizontal system
- Trigger system
- Imaging system
All of these systems are used by the oscilloscope to provide the most information about the signal and to allow the user to determine the integrity, predictability and reliability of these signals for any number of applications.
History of Oscilloscope
The oldest way to create an image of a waveform was to measure the voltage or current of a rotating rotor at certain points around the axis of the rotor and note the measurements made with a galvanometer. By slowly advancing around the rotor, a general standing wave can be drawn on graphing paper by recording the degrees of rotation and the meter strength at each position. These processes were automated by the step-by-step waveform measurement method by Jules François Joubert. This process could only produce a very rough waveform approach. But it was the first step in the science of waveform imaging.
The first digital storage oscilloscope was produced by Nicolet Test Instrument of Madison. It used for vibration and medical analysis with a low-speed analog-to-digital converter. After producing high-speed digiterz in Switzerland, the digital storage oscilloscope which has high speed, was developed by Walter LeCroy in United States of America. Walter LeCroy is one of the best developers of oscilloscopes in the world.
Digital oscilloscopes also led to the production of hand-held digital oscilloscopes. A handheld oscilloscope is a real-time oscilloscope, usually using a monochrome or a colored liquid crystal display. With the increase in the prevalence of computers, computer-based oscilloscopes are becoming increasingly common. The PC can be part of an oscilloscope or can be used with an oscilloscope. In oscilloscopes, a signal is captured on external hardware and transmitted to the computer where it is processed and displayed.
Digital storage oscilloscopes use a fast analog-to-digital converter to record and show a digital repreresentation of waveform. The digital storage oscilloscope allows to show pre-trigger events and troubleshooting of electronic glitches.
Digital oscilloscopes used today have emerged as a result of the development of oscillographs, cathode ray tubes, analog oscilloscopes and digital electronics.
Digital oscilloscopes have become widespread since the 1980s.
How does the Oscilloscope work?
Oscilloscopes are of two types :
- Digital Oscilloscopes
- Analog Oscilloscopes
Analog Oscilloscopes :
Although analog oscilloscopes are not preferred today, they work just like old tube televisions. They work with the technique of forming an image on a phosphor screen on the principle of transmitting the incoming signal to the coils used to deflect the electron beam formed in the cathode ray tube.
Digital Oscilloscopes :
These days, typical high-end oscilloscopes are digital devices. They connect to personal computers and use their displays. It can connect the oscilloscope to PC. Digital oscilloscopes, on the other hand, work on the principle of sampling the signal from the input thanks to high-speed microprocessors. The advantage of this is that the signal can be stopped at any time, triggered at the desired level, recorded and created again. In addition, although there is no theoretical limit in analog oscilloscopes, the sampling rate of the device you will purchase will determine the maximum frequency of the signal that you can measure in digital oscilloscopes.
Digital oscilloscopes can be classified as :
- Digital storage oscilloscopes (DSOs)
- Digital phosphor oscilloscopes (DPOs)
- Mixed signal oscilloscopes (MSOs)
- Digital sampling oscilloscopes
Using Oscilloscope - How to Use Oscilloscope?
The vertical (y) axis of the image formed on the oscilloscope screen shows the amplitude, that is, the intensity of the measured signal. The horizontal axis shows the time.
Buttons and Tasks
Volts / Div: Determines the vertical resolution of the signal displayed on the oscilloscope. By rotating this knob, we can adjust how many V voltages correspond to each frame that appears on the screen in vertical steps. Generally, we have the possibility to change this resolution in various steps between 1mV and 5V.
Secs / Div: Determines the horizontal resolution of the signal on the screen. We set how many seconds, milliseconds or microseconds each horizontal frame will represent through this button.
AC / DC Coupling :
- AC: Measures alternating current signals.
- DC: Measures direct current signals.
Trigger: This setting is only available on digital oscilloscopes. With this button, we set that the oscilloscope will start measuring when the signal reaches. If the image on the screen jumps to the right and the right, this setting will be useful.
Horizontal Pos: This setting is used to adjust the horizontal position of the signal on the screen. It is a very useful function for signals that do not fit on the screen.
Vertial Pos: This setting is used to adjust the vertical position of the signal on the screen. Especially when examining two different signals at the same time, it can be very useful to find the two signals in different positions vertically using this feature.
Auto: This button is only available on digital oscilloscopes. We can easily adjust the vertical and horizontal resolution of the measured signal in the most suitable way to the screen by pressing this button.
Stop: This button, which is only for digital oscilloscopes, allows us to take a snapshot of the current state of the signal and examine it in more detail.
Where is the oscilloscope used?
The oscilloscope can be used in many troubleshooting and research processes:
- It is used to determine the frequency and amplitude of a signal that may be critical in a circuit's input, output or internal systems. So you can tell if a component in your circuit is faulty.
- It is used to determine how much noise is in the circuit.
- In determining the shape of a wave - sine, square, triangle, complex, etc.
- It is used to measure the phase differences between two different signals.
- Oscilloscopes can be found in technical services, R&D and production departments and laboratories.
What do oscilloscopes measure?
Oscilloscope is used for many measurements. The most prominent are;
- Voltage Measurements
- Time and Frequency Measurements
- Pulse Width and Rise Time Measurements
- Phase Shift Measurements
- Digital Oscilloscope
- Analog Oscilloscope
- USB Oscilloscope
- Portable Oscilloscope
Let's explain these variants respectively.
Digital Oscilloscope: Oscilloscopes of the type that we will encounter most frequently are digital ones. They operate with a fast and high-resolution analog-digital converter (ADC) circuit and a microcontroller that controls the display functions with the button. Convenient features such as automatic measurement, frequency analysis, and FFT, image memory are made possible by digital oscilloscopes. It can transfer full screen images, video, or waveform data
from an oscilloscope to PC.
Analog Oscilloscope: These devices, working on the principle of deflection of the electron beam in a cathode ray tube on the screen by the input signal applied to the vertical and horizontal deflector coils, form the oldest type oscilloscopes known.
USB Oscilloscope: These devices working on the same principle as digital oscilloscopes do not have a screen. They use software running on our computer to display the signal.
Portable Oscilloscope: They are devices with limited features in terms of small size and easy transportation. Laboratory type oscilloscopes with battery and charge models are devices that can give high accuracy results. Portable Oscilloscope have an extra durable protective casing that is especially used for field applications and fault-discovery.
Though it should be noted that many of these pocket-sized oscilloscopes cram a ton of features into their tiny frames. It provides quality accuracy, tons of features, and robust data logging capabilities for both the scope and the integrated digital multimeter.
Whether you are a professional or a student, you need a accurate, user-friendly and portable oscilloscope.
Portable oscilloscopes are generally employed for evaluating, calculating, and checking in technology, engineering, telecoms, auto-research, and for heavy industry purposes.