Research On Optimization Techniques Of Polar Codes And Anti-interference Filtering In Virtual Oscilloscope Systems

In recent years,with the application and development of online education models,virtual experiment simulation teaching has received more and more attention.In order to ensure the effectiveness of interactive signals,this article outlines the principle of polarization encoding and decoding,and proposes an early termination iterative algorithm based on Cyclic Redundancy Check(CRC)for Belief Propagation(BP)decoding to reduce system response.Time delay improves effectiveness.At the same time,the virtual experimental system can flexibly match components,develop instrument development and experimental teaching through the realization of software virtualization of hardware functions.However,the virtual oscilloscope system in this system suffers from serious interference in wireless network transmission and has poor reliability.In response to this problem,programs such as spectrum correction are used to suppress errors,and a virtual experimental simulation model with high reliability is established.In addition,the traditional experimental design and experimental simulation technology has problems such as difficulty in operation and poor scalability.In this regard,this article uses Agent theory and object-oriented operation technology to establish a simulation model of the virtual oscilloscope with good reusability,completeness and scalability.The main contents of this thesis are summarized as follows:1.The research of polarization code with high effective decoding algorithm is carried out for the effectiveness problems such as high delay and slow response speed of wireless networking transmission of virtual oscilloscope system.Based on the traditional polarization code BP decoding algorithm,a new BP decoding early termination iteration algorithm based on auxiliary CRC freeze bits is proposed.The freeze bit BER algorithm takes advantage of the fact that the convergence trend of the average error probability of freeze bits is the same as the convergence trend of information bits,and decides the termination of the iteration by judging whether the average error probability of freeze bits converges or not at the receiver side.In addition,the CRC is further added to the freeze bit BER algorithm,and the iteration is terminated early by the check judgment in the decoding process,which can further reduce the decoding delay.Simulations show that the new algorithm can better achieve the purpose of early termination of iteration,and the performance of the frozen bit BER algorithm with CRC assistance is better than that without CRC assistance.When the signal-to-noise ratio is high and the decoding performance is the same,the early termination iteration of the BP decoding algorithm with CRC-assisted frozen bits reduces the number of BP decoding iterations by about 80%,which greatly reduces the system delay and improves the decoding efficiency.2.Aiming at the problem of serious and poor reliability of wireless network transmission interference of the virtual oscilloscope systems,a discrete spectrum correction scheme based on fast Fourier transform(FFT)and a moving average anti-pulse interference signal filtering analysis with time stamp is proposed.The normalized frequency error is used to suppress the interference to obtain the correction amplitude and correction phase.In the case of eliminating the poor measurement value,the measurement average can be used to replace the measured value to improve the measurement accuracy.In addition,a noise signal prediction module based on long short-term memory(LSTM)network is also designed.The simulation shows that: in the signal measurement range of [1Hz,100 k Hz],the amplitude error after correction can reach 0.99%,and the minimum frequency error is only 0.0023%.3.A low-cost,functionally scalable virtual oscilloscope is developed for a series of problems such as expensive and poor scalability of virtual oscilloscopes in virtual oscilloscope systems.Compressed sensing signal processing technology is used to combine ST's 32-bit series microcontroller chip,field-programmable gate array and other modules with microcomputer.Simulation shows that the virtual oscilloscope has 50 MB bandwidth,100MS/s sampling rate,and flexible programmable software expansion functions such as signal generator,spectrum analysis,amplitude and frequency measurement,while having the waveform display and measurement functions of traditional oscilloscopes.Compared with the existing virtual oscilloscope,it is multi-functional,low-cost,highly scalable and portable.This dissertation mainly studies the simulation design of the object-oriented virtual experimental system,and develops the virtual experimental system for signal processing through the software realization of functional modules,including the optimization of the polarization code structure of the virtual experiment,the analysis of anti-interference filtering technology and Add noise signal prediction module,etc.At the same time,the early termination of the iterative decoding algorithm based on the polarization code greatly improves the response time delay of the system,making it have the three characteristics of high reliability,high efficiency and low complexity,which is very suitable for application in the virtual oscilloscope experimental system.