How to choose digital oscilloscope?
How to choose oscilloscope reasonably as the price difference of oscilloscope nearly 50 times between low-grade with high-grade.
The relationship between the bandwidth selection and the highest signal frequency to be measured is needed if accurate measurements are required. Let’s check below example, there is one pulse signal with 50 MHZ, to ensure scope of signal and accuracy of rising delay, the bandwidth of oscilloscope should be 3-5 times of measured signal’s frequency and the accurate measurement should be 8-10 times or more.
Sine wave: as usual, need more than 5 sampling sites during one period as the waveform will be more close to the actual one with more sampling sites.
Pulse wave: rising delay should be more than 5 sampling sites.
Accurate measurement rising delay should be more than 10 sampling sites.
3. Record length: record length=sample*scanning speed*10, it could also be called waveform observation time.
4. Trigger function: ensure that the measured signal can be captured and synchronized to facilitate the observation and analysis of the measured waveform
Trigger methods: automatic trigger, normal trigger and single trigger
Two kinds of trigger function
1) Edge trigger: all digital oscilloscopes have this function, It refers to positive edge, negative edge trigger, window trigger, before trigger and after trigger.
2）Smart trigger：This is considered perfectly in high-grade oscilloscopes. currently there are: delay trigger, sequence trigger, burr trigger, interval trigger, leakage logic surface trigger, TV trigger, this trigger......
5. Analysis function: Should have very strong automatic processing, computation, test and analysis ability of signal
1）Shape and parameters pass/fail automatic test function
2) Advanced function processing: average, differential, polar, exponential, logarithm, power, square root, envelope, high score system, etc.
3）FFT spectrum operation function from 10k-4m point, with power spectrum, power density, phase vector, imaginary part, real part and other measurements;
4）The direct square analysis can be used for the stability calculation of the direct square test signal from 500 points to 8M points according to various parameters
5）Waveform parameter Trend analysis function, Jitter and time analysis;
6) Could open 2-8 windows to observe original waveform and processed waveform simultaneously.
X-Y display and X-Y+X-T and Y-T display are provided, can also carry on the vernier measurement makes it specially suitable for vector diagram analysis of digital communication signals.
6. Record and print signal
1) Can be stored in a test line on a floppy and hard disk, and can be read on a PC. Some digital oscilloscopes are equipped with built-in, convenient to print and analyze long time signal;
2) Some oscilloscopes also provide VGA interface.
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.
Causes of damage to oscilloscope current probe
The reasons for the damage of the current probe, the methods for preventing the damage and the instructions for using the current probe can be summarized as follows:
Circuit board damage caused by plugging current probe after current amplifier is turned on.
Protection against damage: - do not plug or unplug the current probe while it is still active.
Magnetic ring is fragile material, drop or use too hard when it is easy to damage. Damaged/damaged magnetic rings will result in inaccurate or no longer detectable current.
How to prevent damage and use: - avoid dropping or using too hard.
Magnetic ring coil is thin, over current will cause coil burn out.
Prevent damage method: - avoid the load flow when using.
The current clamp is not aligned, and cracks will make the test inaccurate or unable to measure the current. Be careful how you push the clip.
Method to prevent damage: - when using the current clamp to align. Be careful and be careful when pushing the clip.
The cable can be easily damaged if it is pulled too hard or twisted.
Prevention of damage: - do not use the cable too hard to pull, twist, etc.