Hardware Design Of Storage System In Four-channel Digital Three-dimensional Oscilloscope

As an important test instrument, the advantageous performance of digital oscilloscope is drawing more attention of engineers. As the test signal is more and more complicated, users put forward strict requirements to the oscilloscope in channel numbers, sampling rate, rate of capture, the ability of storage and analysis and so on. This paper is based on four-channel digital three-dimensional oscilloscope as hardware platform, researches and designs the four-channel storage system and its key technology.The design requirements of storage system in four-channel digital three-dimensional oscilloscope are as follows: maximum storage depth is 140 Mpts when single-channel working in 4GSa/s sampling mode, maximum storage depth is 70 Mpts when dual-channel working in 2GSa/s sampling mode, waveform capture rate should be over 200,000 wfms/s, frame number of recording should be over 100,000 frames, and etc. This paper mainly completes the hardware design of storage system, designs multiple storage methods includeing the general store, deep storage and rapid sampling, studies various storage application functions including segment storage and hardware real-time waveform recording, which makes the function of storage system more complete and improves the performance. The specific points are as follows:1. Deep storage function of high speed data with four channels is designed and implemented. The design uses several DDR2 particles synchronous parallel to store, researches and designs several key technologies to ensure storage performance boost: alternate storage technology solves the problems, which are discontinuous waveform caused by data update and slow update; implemented variable depth of storage technology to adjust the storage depth, to improve the waveform refresh rata under the deep storage, and improve the system response speed.2. Auxiliary modules of the storage system are designed, which includes digital trigger module and high-resolution acquisition module. In a high speed parallel acquisition storage system, the traditional analog trigger can only realize trigger location accurate positioning to serial data, and it takes more time for hardware circuit to fine trigger point. Digital trigger makes up for the deficiency of the both, and can locate the position of trigger point in the parallel data quickly and accurately; High-resolution acquisition module increases the processing method before or after data storage, can effectively filter out the noise component of acquisition signal, increases the ENOB of acquisition system.3. The functions based on the deep storage are researched and designed, which includes segment storage and hardware real-time waveform recording. Segmented storage technology not noly improves the waveform capture rate under deep storage effectively, but also can capture the details of the abnormal signal and quick positioning analysis. Hardware real-time waveform recording technology has these advantages including large-capacity recording, faster speed and recording waveform without storage post-processing, which can effectively improves the speed of retrieval and the efficiency of analysis for real-time waveform.