| With the development of electronic information technology,the analog signal presents a highly complex changing trend.To realize the capture and analysis of such a signal,electronic measuring instruments need to have a variety of waveform data processing technologies.In addition,in the face of some small space and outdoor test occasions,the use of multiple types of instruments will increase the complexity and cost of testing,so the reuse of the functions of the measurement instrument becomes particularly important.Therefore,in order to meet the needs of diversified waveform data processing and multi-functional joint testing,thesis focuses on the design and implementation of its waveform processing and time-frequency measurement modules based on the USB oscillographic analyzer platform,and finally tests and verifies the design results..The main tasks and problems solved in thesis are as follows:（1）Design of high-speed data extraction mode:Firstly,aiming at the problem of extraction point in common acquisition mode,a cascade method of uniform extraction point with arbitrary integer proportion is proposed to realize arbitrary switching of base gear of 2ns/div～50s/div.Secondly,the extraction method of taking the most value for continuous sampling points improves the ability to capture abnormal signals such as glitches.At the same time,the signal-to-noise ratio of the acquisition system is improved by using the average filter extraction method which is simple and easy to realize at the digital end,and thus the system resolution is improved.（2）Design of hardware interpolation:In order to solve the problem that the real-time sampling rate of ADC is lower than the system display sampling rate,based on the interpolation algorithm of polyphase filter,multi-multiplier interpolation is carried out on the collected data in the form of digital filter and relevant logic codes are realized in FPGA to achieve the maximum interpolation of 100 times.（3）Design of edge triggering of all digital circuits:In order to solve the problem of trigger deviation caused by the difference between the signal acquisition path and the trigger path in the traditional analog trigger,an all-digital trigger system is designed.The level is compared,and the precise positioning information of the actual trigger point is generated to control the acquisition data storage,so that the edge trigger accuracy is improved to 400ps.（4）Design of data transmission and control:In order to meet the requirements of different functional transmission,and according to the interface design between FPGA and USB chip,different control systems are designed to complete the data transmission of corresponding functional modules in the system.（5）Design of time-frequency measurement module:Aiming at the design requirements of multi-function and high integration,a frequency measurement method combining equal precision frequency measurement with multi-period and step measurement cycle is proposed,which achieves the frequency measurement range of 10Hz～1 GHz and makes the measurement accuracy reach±5×10-7.In addition,an implementation method of digital voltmeter with the cooperation of software and hardware is designed.The design of thesis is based on the USB oscillographic analyzer platform.Through the testing and verification of various functional indicators of the waveform processing module,frequency meter and digital voltmeter,the waveform processing module designed in thesis functions normally and the measurement accuracy meets the requirements of the indicators,the work of thesis has been completed. |
