Research On Indoor Positioning Technology Based On Spread Spectrum Acoustic Wave

With the rapid development of communication technology and mobile positioning technology,location information services using outdoor positioning and navigation technology have penetrated into all aspects of life,and people's demand for indoor location information is also increasingly urgent.However,due to GPS and other satellite positioning technologies,they cannot be used indoors.Application,how to achieve indoor high-precision,stable and reliable positioning and navigation has become an urgent problem to be solved.This paper analyzes the current main indoor positioning methods and selects acoustic wave positioning method with high precision,low cost,and not affected by indoor light electromagnetic environment.However,due to the attenuation characteristics,multipath effect,and noise interference of the acoustic wave propagation channel In order to reduce these effects,an indoor positioning technology based on spread-spectrum sound waves is proposed and tested through the built hardware platform.The results show that the system has certain anti-interference ability and high positioning accuracy.The main work of this article is as follows:1.Analyze the propagation characteristics of sound waves in the air,introduce the spread spectrum communication technology for the energy attenuation and multipath effect in the sound wave propagation process,and through the analysis of the related technologies of spread spectrum communication,select the expansion suitable for this system Frequency modulation.2.Research on time synchronization,delay estimation and the spatial layout of the base station,which have a greater impact on positioning accuracy.A time synchronization method between base stations is proposed and the cross-correlation function algorithm is used to determine the propagation delay of acoustic signals.With reference to the satellite constellation geometric distribution evaluation method in satellite positioning technology,the geometrical accuracy attenuation factor(GDOP)is used to simulate and analyze the geometric layout of acoustic wave base stations,and several good layout methods are provided to provide large-scale base station layout reference.3.Based on the principle of spread spectrum modulation and positioning calculation of sound waves,the overall framework of the system is established,the parameters of the main parts of the system are determined,and the generation and processing of the spread spectrum sound wave signals of the system are completed.The main modules of the system platform are implemented,including the application software and hardware development platform,the appropriate sound wave transmitter is selected and the sound wave receiver is designed.4.Use the established spread-spectrum acoustic positioning system to test the transmission of various acoustic signals between circuits and the hardware response error,and remove the error to test the effective communication distance of the system in the indoor environment.And indoor positioning test was carried out.The test results showed that the positioning accuracy was within 10 cm,which verified the feasibility of the spread spectrum acoustic wave indoor positioning system.5.Through the error analysis of the indoor positioning experiment results,for the existing system errors,combined with the satellite positioning differential positioning method,a differential method suitable for the system is designed.The experimental data was analyzed and processed from two aspects,ranging difference method and position difference method.The results showed that the positioning accuracy was improved by 64% and 71.3% after the two difference calculations.