Several Tips for Oscilloscope Using
Oscilloscope is still the necessary tools working on the stage at present, based on the user common problems; we summarized several tips of oscilloscope.
High-speed serial test requirement
Basically, the bandwidth and sampling rate must meet the requirements of the serial signal, then we need to examine whether it is differential signal, and signal analysis of oscilloscope to serial test, such as the trigger and decoding, etc.
Oscilloscope bandwidth
When choose the bandwidth of the oscilloscope; in general, it is 2.5 times of measured signal rate or five times of the highest frequency signal, so that you can see the five harmonics of the signal.
Bandwidth shortage will lose the high frequency signal harmonic component, leading to the inaccurate of time and amplitude test. But even the oscilloscope of the same bandwidth will show different time to rise. For applications, the measurement errors on the rise are crucial, and in a data signal, it has a very big impact on the eye chart opening degree. Because of this, rise time is very important to the measurement equipment (oscilloscopes) in domain indexes.
At present the extensive applied printed circuit boards, connectors, cable and integration module rise time is limited, so that after the high speed signal through transmission, the high coefficients loss will be serious. Many new third generation standards (USB3.0, PCIE Gen3, and 10 G-KR) have to take that into account, so the required bandwidth is much lower than before. Of course, there are some exceptions, which demand higher bandwidth, such as 100 G Ethernet solutions, it uses complex modulation technology (DP-QPSK), asks four analog input and more than 20 GHz bandwidth to analyze. In view of the application, TEK has announced that its bandwidth more than 30 GHz oscilloscopes will be launched later in the second half of this year.
The sensitivity of testing instruments
In order to improve the sensitivity of the testing instrument, we should choose the right bandwidth, overlarge bandwidth will increase noise. In vertical set, we should make the signal fulfill the screen as far as possible, thus make full use of the AD digits. We can adopt waveform average, right probe bandwidth, or choose high resolution (Hi-res) collection model and so on.
The capture of the abnormal phenomenon
Using DPX technology, and open the infinite afterglow, a few seconds we can see abnormal signals which we will ignore usually. This performance improves the witness appeared in digital system transient events, the transient events include short pulse, burr and convert error, etc.