Yang Kuojun, Tian Shulin, Zeng Hao, Qiu Lei, Guo Lianping
School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, China.
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore.
Rev Sci Instrum. 2014 Apr;85(4):045102. doi: 10.1063/1.4869871.
In traditional digital storage oscilloscope (DSO), sampled data need to be processed after each acquisition. During data processing, the acquisition is stopped and oscilloscope is blind to the input signal. Thus, this duration is called dead time. With the rapid development of modern electronic systems, the effect of infrequent events becomes significant. To capture these occasional events in shorter time, dead time in traditional DSO that causes the loss of measured signal needs to be reduced or even eliminated. In this paper, a seamless acquisition oscilloscope without dead time is proposed. In this oscilloscope, three-dimensional waveform mapping (TWM) technique, which converts sampled data to displayed waveform, is proposed. With this technique, not only the process speed is improved, but also the probability information of waveform is displayed with different brightness. Thus, a three-dimensional waveform is shown to the user. To reduce processing time further, parallel TWM which processes several sampled points simultaneously, and dual-port random access memory based pipelining technique which can process one sampling point in one clock period are proposed. Furthermore, two DDR3 (Double-Data-Rate Three Synchronous Dynamic Random Access Memory) are used for storing sampled data alternately, thus the acquisition can continue during data processing. Therefore, the dead time of DSO is eliminated. In addition, a double-pulse test method is adopted to test the waveform capturing rate (WCR) of the oscilloscope and a combined pulse test method is employed to evaluate the oscilloscope's capture ability comprehensively. The experiment results show that the WCR of the designed oscilloscope is 6,250,000 wfms/s (waveforms per second), the highest value in all existing oscilloscopes. The testing results also prove that there is no dead time in our oscilloscope, thus realizing the seamless acquisition.
在传统数字存储示波器（DSO）中，每次采集后都需要对采样数据进行处理。在数据处理期间，采集会停止，示波器对输入信号无响应。因此，这段时间被称为死区时间。随着现代电子系统的快速发展，偶发事件的影响变得显著。为了在更短时间内捕获这些偶然事件，需要减少甚至消除传统DSO中导致测量信号丢失的死区时间。本文提出了一种无死区时间的无缝采集示波器。在这种示波器中，提出了将采样数据转换为显示波形的三维波形映射（TWM）技术。利用该技术，不仅提高了处理速度，还以不同亮度显示波形的概率信息。因此，向用户展示了三维波形。为了进一步减少处理时间，提出了同时处理多个采样点的并行TWM以及在一个时钟周期内处理一个采样点的基于双端口随机存取存储器的流水线技术。此外，使用两个DDR3（双倍数据速率三倍同步动态随机存取存储器）交替存储采样数据，从而在数据处理期间采集可以继续。因此，消除了DSO的死区时间。此外，采用双脉冲测试方法测试示波器的波形捕获率（WCR），并采用组合脉冲测试方法全面评估示波器的捕获能力。实验结果表明，所设计示波器的WCR为6250000 wfms/s（每秒波形数），是所有现有示波器中的最高值。测试结果还证明我们的示波器没有死区时间，从而实现了无缝采集。
