Ⅰ.Overview
Digital circuit is developed rapidly in the eighties, whose testing tools - digital oscilloscope. They are springing up like mushrooms. As the price of a digital oscilloscope is more expensive than an analog oscilloscope. So we should choose a digital oscilloscope according to our needs. We shouldn’t go after high–index blind, otherwise will make a great unnecessary waste. The price of a low level oscilloscope is out of line with the high-end quality one. The difference between them is almost 50 times in the price, among (8,000-50 million) RMB.
Ⅱ. How to choose is reasonable
1. Bandwidth
If you want to accurate the relation between the selection bandwidth and the highest frequency of the signal. First, we look at the following example: a 50MHz pulse signal.
From the graph which on different bandwidth oscilloscope, we should choose the bandwidth of the oscilloscope 3-5times as the signal frequency and accurate measurement 8-10 times or more as the signal frequency, as in order to ensure the extension of the test signal amplitude and increase the accuracy.
2. Sampling
Sine Wave: More than 5 samples / cycle (general requirements) In fact, the more sampling points are closer to waveform.
Pulse wave: rising edge more than 5 sampling points.
Accurate measurement of the rising edge is more than 10 sampling points.
3. Storage length
Length = samples stored *the speed of scanning * 10, it is also called the formula of waveform observation time.
4. The trigger function
Must be ensured the oscilloscope can capture and synchronize the signal. It is good for the observation and analysis the measured waveform.
Trigger in three ways: automatic trigger, the normal trigger, single trigger.
Trigger divided into two categories according to function:
⑴Edge trigger
All digital oscilloscopes have this function, it is referring to positive edge, negative edge trigger, the trigger window, before the trigger and post trigger.
⑵Smart trigger
In the high-end oscilloscopes have been well considered. There are trigger delay, the order trigger, glitch trigger, the trigger interval, the logical side leakage triggered, TV trigger, the trigger on currently oscilloscopes.
5. The analysis
The analysis should have a strong automatic processing, calculation, testing and analysis for the measured signals.
⑴The test automatic sub-function can tell whether pass or fail for the shape and parameter.
⑵High function handles including average, differential, most point, exponential, logarithmic, power, evolution, envelope, high score system and other operational functions.
⑶The operation function of FFT spectrum can from 10K-4M points. The functions including the power spectrum, power of the density, the phase vector, imaginary part, real part and other measurements.
⑷Histogram analysis can test stability of the signal from 500-8M points according to various parameters.
⑸It can analysis the trend of the waveform parameters as well as jitter and the time.
⑹ While observing the original waveform and the waveform after treatment, it can open 2-8 windows.
⑺It can provide X-Y display, as well as the display function of XY, XT and YT. It also provides cursor measurement. In particular, it is suitable do vector diagram analysis for the digital communication signal.
6 Storage and print signals
⑴Some digital oscilloscopes with a built-in printer, which is easy printing and analyzing for long signal.
⑵Some digital oscilloscope also offers VGA interface.
Youroscilloscope.com offers all kinds of cheap digital oscilloscopes. Welcome wholesale and drop ship from China.