Research On Eye Diagram Measuring Method And Parameters Extraction Based On Vector Network Analyzer

This paper is studying a method of generating eye diagram and extracting parameters of eye diagram based on the vector network analyzer(VNA).The eye diagram test is an important means for the evaluation of quality of high-speed signal.The VNA is commonly used as testing instruments,especially in the field of high-speed circuit and microwave,so the study of the eye diagram generation method based on vector network analyzer has the practical significance.This paper presents an eye diagram generation method by the means of convolution between pseudo-random sequence and impulse response,and an eye parameters extraction method based on K-Means clustering.Therefore,this paper is divided into two part: the one is the eye diagram generation,another is the calculation of the eye diagram parameters.In the process of the eye diagram generation,the S parameters measured by the vector network analyzer could be used as the required data sources which generate the eye diagram.Firstly,starting from the theory of Fourier transform,the corresponding relations between time domain and frequency domain have been discussed.Through the repeated analysis and comparison,this paper has decided to use the inverse Chirp-Z transform to convert the data from the frequency domain to the time domain.In the process of time domain conversion,the influence of the windowing is also discussed,and the influence of different window functions on the time domain impulse response is compared,and the Kaiser window is selected as the required window function.After adding window,the time domain impulse response can be obtained by Chirp-Z inverse transform.This paper uses the pseudo-random sequence as the generation of eye diagram stimulation codes,discussed some properties and the generation mechanism of the m sequence at the same time.After generating an m-sequence,m-sequence and impulse response convolution,and the convolution and the cutting,stacking,the formation of the eye diagram.In the process of the eye diagram parameters extraction,the K-Means clustering algorithm is applied to the calculation of parameters.Eye diagram parameters extraction method proposed in this paper is as the breakthrough point to the eye at the intersection of time value,and the eye data segmentation,it can be divided into several sub sets,and these sub set K-Means clustering to get some key value.According to some of the key value obtained,the definition and calculation formula with the eye parameters,calculate the rest parameters of all the eye diagram.At the end of the paper,the eye diagram test of differential line based on the method proposed in this paper is verified.During the experiment,the differential mode,the common mode,and the single ended mode respectively,using the method proposed in this paper to generate the eye diagram and calculate the relevant parameters of eye diagram.Based on PLTS software test results as reference results,compared with the eye diagram and the eye diagram parameters calculated using the method of generating,verify the correctness and feasibility of this research method.