Research On Real-time Signal Measurement Technology Based On Information Entropy And Its Application

Modern electronic signals become increasingly complicated and diversified,and the information carried by the signals is diverse,random and of large amount.How to effectively extract the information and realize real-time acquisition and analysis of wideband,transient and non-stationary signals has brought challenges to modern signal measurement.On one hand,high-speed and high-accuracy acquisition is pursued to capture as more signal details as possible;on the other hand,mass data acquired at high sampling rate with high resolution have brought troubles to the real-time processing and analysis of signals,which affect the system response seriously.In order to meet this challenge,time-domain measurement based on real-time sampling and processing has attracted wide attention and has become the mainstream of modern signal measurement.While the main indicators of time-domain measurement are accuracy and speed,the accuracy and the speed of signal acquisition and processing become the key to ensure the performance in time-domain test system based on A/D conversion.Information entropy expresses the probability of discrete random events in numerical form and measures the degree of uncertainty of information.From the perspective of information entropy,transient and abnormal components superposed in signals make the information entropy different,which lays a foundation for improving the performance of real-time signal measurement.Based on analysis methods of information entropy,this paper mainly discusses the real-time signal measurement technology.Aiming at improving the accuracy and speed in time-domain measurement,theories and applications of high-resolution acquisition,abnormal signal detection,transient signal measurement,three-dimensional wave imaging and seamless measurement have been reaserched as follows:(1)High-resolution acquisition algorithm based on maximum entropy principle.An information entropy-based data fusion and average-based decimation-filtering algorithm is proposed.For single acquiring signal,resolution is improved through eliminating gross error in quantization by utilizing the maximum entropy of sample data with further noise filtering via average-based decimation after data fusion of efficient sample data under the premise of oversampling.No subjective assumptions and constraints are added to the signal under test in the whole process,and there is no impact on the analog bandwidth of digital acquisition system under actual sampling rate.(2)Abnormal signal detection method based on singular spectrum entropy and power spectrum entropy.Acording to the information entropy characteristics in both time domain and frequency domain,the singular spectrum entropy and power spectrum entropy,which represent the complexity of signals,are used as trigger conditons in signal acquisition.An abnormal signal detection system based on two-stage trigger comparison is designed.By the control of common trigger and information trigger together,the feature extraction and anomaly identification of measured signal are realized,which provides a new way for realization of the abnormal signal detection in time-domain test instrument.(3)Real-time measurement technology of transient signal based on approximate entropy.The complexity(amount of information)of measured signal is quantitatively described by the approximate entropy value,and the characteristic signals are captured self-adaptively under the control of the approximate entropy.By extracting the critical or useful information and removing the redundant or useless information,the time consumption of processing data and displaying waveforms is reduced,and the real-time performance of transient signal measurement is improved.A new method for the design of electronic test instrument with seamless measurement capability is also provided.(4)Real-time display technology of three-dimensional waveform.The effects of direct three-dimensional wave imaging mechanism and simple three-dimensional waveform mapping technology on realizing real-time signal measurement are analyzed.The special three-dimensional wave imaging mechanism and dynamic zoom technology of three-dimensional waveform are proposed and applied to the digital oscilloscope,which enhances the real-time performance of signal measurement.(5)Design and implementation of digital oscilloscope with seamless measurement capability.The conditions of realizing “seamless measurement” of digital oscilloscope are discussed and a digital oscilloscope with “quasi-seamless measurement” capability is designed by improving the system structure and optimizing the display mechanism.On this basis,the "seamless measurement" of the key information carried by the measured signal in time domain is achieved by using the method of characteristic signal extraction based on approximate entropy.In addition,the abnormal signal detection is conducted by the trigger system based on singular spectrum entropy and power spectrum entropy,and the effective number of samples is improved by the high-resolution acquisition function based on maximum entropy in the oscilloscope.