Occasional signal observation using the high capture rate of SIGLENT SDS2000 Series oscilloscope

SHENZHEN, China - Jan. 2, 2014 - PRLog -- When purchasing a digital oscilloscope, people usually pay close attention to the bandwidth, real time sampling rate, memory depth and channels, but neglect easily the capture rate, which has been proved to be typically important for performance measuring of a oscilloscope.

Keywords: SIGLENT, digital oscilloscope, capture rate, DPO Oscilloscope, SDS2000

At first, we will introduce you the working principle of digital oscilloscope.

In traditional digital oscilloscope, waveform data processing and display are all completed in CPU, which becomes the bottleneck for waveform data acquisition, processing and display. Only when processing of the previous frame completed, the next frame will start. Plenty of time will be cost for only waiting in this way. Dead time is defined as the waiting time between two neighbouring acquisition frames. Since the dead time of traditional digital oscilloscope is too long, occasional glitches are hard to capture.

The dead time generally occupies nearly 99 percent of the whole time, and increasing capture rate is an efficient way to reduce the dead time.

Instead of traditional waveform acquisition, processing technology, SIGLENT SDS2000 series oscilloscope adopts the innovative FPGA technology to complete waveform processing and display, which reduce the dead time to a large extent.

In hardware debugging process, many engineers usually find that during the later process, when the main components of circuit board had been welded completely, bugs will be found a little while after system runs in the process of function verification. To find out the reason, they are likely to inspect the critical clock signal and enable signal firstly, but usually find nothing, which eventually makes them to believe that there must exits software debugs. If you know more about the dead time, capture failure of occasional glitches may likely explain this phenomenon.

In generally, the most simple and intuitive way to capture occasional glitches is to trigger in “Edge”mode and turn the “Persist”, which is a efficient way to capture the abnormal pulse that appears every tens of thousands of waveform cycles.

It seems a perfect way to capture abnormal signal, but if is it efficient for all abnormal signal? The answer is no. By turning on the “Persist”, the oscilloscope will accumulate previously appeared waveforms, but not waveforms appeared in the dead time.

At time base of 50ns, compared with the 200wfms/s capture rate of traditional digital oscilloscope, the capture rate of SDS2000 series super phosphor oscilloscope could reach to 110,000wfms/s, making a easier capture of occasional glitches and abnormal signal.