Research On Indoor Positioning System Based On Carrier Phase Difference And Wireless Sensor Network

Traditional indoor positioning methods such as Wifi and Bluetooth have low positioning accuracy in non-line-of-sight environments,while UWB positioning systems require extremely high node synchronization,which increases deployment costs.The use of carrier phase difference for positioning does not require strict time synchronization and has high positioning accuracy in indoor environments.Therefore,this article combines carrier phase difference positioning technology with wireless sensor network technology and proposes a method based on carrier phase difference and wireless transmission.The indoor positioning system of the sensor network uses a dual-antenna structure sensor node to measure the phase difference of the signal source carrier,and realizes the summary of the phase difference of the distributed sensor nodes with the help of a wireless sensor network.The article mainly discusses the specific implementation of the positioning system from four aspects: carrier phase difference positioning principle,wireless sensor network architecture and communication mechanism,node design and positioning algorithm.The specific research content is as follows:The paper first introduces the positioning principle of the system,and then uses HFSS simulation software to establish a 433 MHz omnidirectional antenna model for carrier signal transmission and reception.By simulating the radiation field phase of the antenna model,it is verified that the carrier phase difference measurement value of the dual antenna structure model is equal to the actual distance.It proves the feasibility of the positioning scheme in an ideal environment.In response to the data collection requirements of the distributed sensor nodes in the positioning system,the paper designs a tree-shaped dual-channel wireless sensor network topology.On this basis,the time synchronization algorithm based on TPSN is studied and the TDMA data transmission mechanism is used to improve the data transmission speed and node coordination ability of the sensor network.In the experiment part,the time synchronization characteristics and channel quality of the network are tested,and the results show that the indicators of the wireless sensor network meet the design requirements of the positioning system.The paper designs the signal source,sensor node and base station node respectively: the main frame of the positioning system is built using the STM32F103 logic control chip and the CC2630 wireless communication module,the ADF4351 digital frequency synthesizer and the AD8302 phase measurement chip are used to detect the target location information.Aiming at the problem of solving the nonlinear equations(hyperbolic equations)of the positioning system,the paper analyzes the classic Chan algorithm and Taylor algorithm,and proposes a least squares iterative method based on prior coordinates and Taylor series expansion by improving the latter.On the premise of ensuring the algorithm convergence,the problems of sensor information redundancy and measurement error interference in the system are solved.The MATLAB simulation results and the final positioning experiment all prove the effectiveness of the algorithm.