Twelve tips of oscilloscope you must know
(1). The most valuable index of oscilloscope ---Bandwidth, class parameter
(2). How high is the sampling rate?
Generally speaking, the sampling rate is 5 times the bandwidth, such as 200M oscilloscope, with 1G sampling rate is ok.
The pursuit of higher sampling rate is nothing more than to catch small burrs, but these high frequency burrs have been filtered out in the bandwidth layer, and higher sampling rate cannot bring good benefits.
(3). What is the difference between normal trigger and automatic trigger?
Normal trigger, it will sample the waveform only with trigger event satisfies the condition.
Automatic trigger, after wait for a moment, if there is no eligible trigger events occur, the oscilloscope will force the trigger function and start sampling. As random trigger position, the waveform will show unsteady. If above sequence occurs, please adopt normal mode.
(4). How to catch abnormal signal under uncertain condition?
You could catch the signal with template trigger.
When the template trigger is turned on, the template actually comes as a layer. It will constantly detect whether there is waveform that will touch the area of the template. When there is waveform that touches the template, a signal will be detected and it will be filtered and displayed.
(5). Are those channels isolated of oscilloscope?
No. Bottom of oscilloscope is connected with the earth, it could not be connected directly with the zero line.
To isolation, transformer could directly measure 220V city power, however, this is not recommended, and the safest and correct method it to use difference probes.
(6). Which is more accurate between oscilloscope and multimeter when measure voltage?
The vertical resolution ratio of general oscilloscopes is 8 bits. The measure accuracy is related to vertical resolution ratio and vertical gear.
The accuracy of multimeter is much higher. ADC of six and a half meter is up to 24 bits. That of handheld meter is far more than 8 bits. The voltage measured by the multimeter is more reliable.
(7). Differences between probe X1 and gear X10?
Two important points
Different attenuate bandwidth, signal x1 gear amplitude does not decay. X10 gear signal decay to 1/10 of original signal.
Different bandwidth, bandwidth of X1 gear is almost 10M, and 250M for X10 gear.
(8). Does the general oscilloscope probe need to be calibrated periodically?
The standard does not have a specific metering specification for the probe, but for passive probes, at least the probe compensation must be adjusted when the probe is replaced and the probe switches channels.
(9). What is main factor determines the price of oscilloscope probe ?
The main determinants of price are, of course, bandwidth and functionality.
There are many types of oscilloscope probe, different performance, such as high voltage, difference, active high-speed probe and so on, the price also from a few hundred yuan to nearly ten thousand dollars.
The probe is part of the oscilloscope contact circuit. A good probe can provide the fidelity required for testing.To do this, even passive probes must have a very large number of passive device compensation circuits (RC networks) inside.
(10). Is there any way to measure the working condition of high frequency transformer or inductor core by oscilloscope?
Can rely on the oscilloscope's own power analysis software to do, there is a function - B-H curve analysis, it can reflect the working state of the magnetic core, but also can measure the dynamic inductance value, and get the core loss.
(11). Can an oscilloscope perform Fourier decomposition?
Modern digital oscilloscope mostly has FFT function, but need to pay attention to FFT can analyze the number of points, which directly determines the accuracy of FFT analysis results, avoid spectrum leakage.
(12). Can oscilloscope filter? Such as low pass filtering of PWM wave?
Oscilloscopes typically have a 20MHz bandwidth limit, and this is a hardware filter.Some oscilloscopes also support software filters with adjustable cutoff frequencies.
What does an oscilloscope do?
Oscilloscope is a kind of instrument which is widely used to display the trace change of instantaneous value measured.It can transform the electric signal invisible to the naked eye into visible image, which is convenient for people to study the change process of various electric phenomena. An oscilloscope USES a narrow beam of high-speed electrons to produce tiny points of light by hitting a surface coated with fluorescent material. Under the action of the measured signal, the electron beam ACTS like the tip of a pen and can plot the instantaneous value of the measured signal on the screen.Use oscilloscope to be able to observe all sorts of different signal amplitude the waveform curve that changes with time, still can use it to test all sorts of different electric quantity, if voltage, current, frequency, phase difference, adjust amplitude to wait a moment.
Digital oscilloscope automatic verification system
With the development of electronic technology, digital oscilloscope with the digital technology and software greatly expanded the ability to work, the early products of low sampling rate, there is a big dead zone time, less than be improved screen refresh rate low, difficult to observe before modulation signal, communication eye diagram, such as composite video signal is more and more easy to observe. Digital oscilloscope can calculate and analyze data, which is especially suitable for capturing all details and abnormal phenomena in complex dynamic signal.In order to make the oscilloscope work in a qualified state, it is an urgent task for the test engineer to verify the oscilloscope regularly, quickly and comprehensively and to ensure the traceability of its value.
Manual verification is inefficient and prone to errors. The verification of each oscilloscope requires the test engineer to read a lot of data.The automatic test system has the characteristics of accurately and quickly measuring parameters, intuitively displaying test results, automatically storing test data and so on.It will be the trend of instrument verification to realize program control verification of oscilloscope with automatic test system.
GPIB, VXI and PXI are the standard buses of automatic test system. GPIB has won the recognition of users for its stable performance, convenient operation and low price.Here, GPIB is selected as the bus of the test system.
The hardware of automatic verification system of digital oscilloscope based on GPIB is composed of GPIB controller, FLUKE5500A, verified digital oscilloscope, PC and printer