| With the development of the electronic information industry,the characteristics of modern electronic equipment with mixed signals are becoming more and more obvious.Facing the test requirements of multiple analog signals and multiple digital signals,the traditional four-channel oscilloscope is not competent.The mixed signal oscilloscope organically combines the test functions of logic analyzer and digital storage oscilloscope,which can meet the needs of users for simultaneous test and analysis of multi-channel signals.Because the hybrid oscilloscope has the largest number of channels among many types of digital oscilloscopes,the precision of multi-channel synchronization is the product performance that users care about.If the synchronization accuracy of the hybrid oscilloscope is insufficient,it will produce a great error for the study of the synchronization relationship between multiple signals of the tested system.The time base function of oscilloscope can be adapted to display input signals of different frequencies,which determines the ability of oscilloscope to expand and compress signals.Therefore,this thesis focuses on synchronization technology and time base technology in hybrid oscilloscope.To sum up,the specific research content of this thesis is as follows:1.Focusing on the goals of high sampling rate,multi-channel,ultra-wide time base,and high synchronization accuracy,this work designs a mixed-signal acquisition system architecture based on "multi-ADC + multi-FPGA + industrial control computer".2.Focusing on the need to improve multi-channel synchronization indicators,design a clock solution that meets the synchronization accuracy.JESD204 transmission technology is used to design the analog channel signal sampling synchronization scheme,and the Ser Des transmission technology is used to design the data storage synchronization scheme.The analog channel synchronization accuracy can reach ±50ps.Using GT acquisition and transmission technology to design multi-digital channel acquisition synchronization scheme,the synchronization accuracy of digital channels can reach±200ps.On this basis,further research is carried out to realize multi-channel analogdigital cross-trigger synchronization,and the synchronization accuracy can reach ±1ns.3.In order to reduce the order and resource loss of the interpolation filter,this work proposes a multi-rate interpolation structure based on a two-stage FIR frequency domain interpolation filter.This structure can achieve a maximum interpolation magnification of500 times with only a 598-order filter.On this basis,the multi-level FIR polyphase interpolation filtering algorithm is further studied,and the order of the filter is reduced to378 under the same interpolation magnification by optimizing the implementation structure.This scheme can realize the interpolation function of different magnifications on the basis of only designing the anti-image filter coefficient once,which can reduce the difficulty of designing the interpolation time base.4.In order to increase the amount of data transmitted and the transmission rate of the scrolling mode,this thesis realizes the real-time scrolling display function of fullchannel data through the transmission method of direct storage access.This feature has a high resolution and peak detection display mode,in the fastest scrolling display gear,waveform connection signal will not be lost.Based on the research on the multi-channel mixed signal oscilloscope,this thesis designed and implemented a physical test prototype with an analog channel 10 GSPS sampling rate,a digital channel 5GSPS sampling rate and a time base range of 20ps/div-5000s/div.The test prototype provides a verification platform for the main indicators of the system and the key technologies involved in the research.The test results show that the functions of the mixed-signal oscilloscope based on the synchronization technology and the time base design technology can meet the index requirements. |
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