Software Design And Implementation Of Frequency Measurement Method Without Predictive Filter

Researching high-performance and multifunction electronic measuring instruments,which makes the instrument have both spectrum analysis and network analysis functions,has become the development focus of the instrument industry.This can improve the utilization efficiency of the hardware,reduce the expenditure,reduce the system error,and save the test time.However,the traditional spectrum analyzer and the network analyzer have device conflicts in the hardware structure.If the spectrum function and the network analysis function are integrated,it is indispensable to utilize a new methods for pectrum analysis or image signal rejection.In this thesis,the frequency measurement method without pre-selected filters is implemented in the form of software,and is called in some instruments(such as vector network analyzers)that cannot add pre-selected filters,which can give these instruments spectrum testing functions.The research work of this thesis is as follows:(1)Combining the spectrum analysis principle of superheterodyne spectrum analyzer,this thesis analyzes two situations in which the image signal can be generated.A mirror frequency suppression method,based on random search algorithm and statistical method,is selected to realize the image signal rejection which is based on digital signal in the measurement process.(2)In order to facilitate software programming,this thesis will detail the flow of the frequency measurement method without pre-selection filter: firstly,set the parameters of the spectrum analysis software module;secondly,convert the electronic signal into digital signal through the hardware circuit;Thirdly,the digital signal need a series of operations such as windowing,FFT transformation,signal calibration,etc.Finally,the image is image suppressed by the image suppression method based on the digital signal.(3)In this thesis,the overall framework design and operation flow design of the software module without pre-selected filter frequency measurement method are carried out.In the overall frame design,the software module explains the three parameters of the parameters required for frequency measurement,data communication with hardware and users,and all internal functional modules for spectrum analysis.In the design of operation flow,this thesis implements two design schemes: single thread and multi thread.(4)The software implementation of this thesis is tested on a vector network analyzer in the form of a DLL file.It is used for memory consumption analysis,time-consuming analysis and spectrum analysis result verification.According to the experimental results,this thesis summarize the measurement parameters that affect the performance of spectrum analysis.