Research On Indoor Visible Light Location Algorithm Of DVB-T Based On SoC

In recent years,people's demand for location services has been increasing,such as commodity positioning in business districts,and route guidance in traffic places.And because LED has the advantages of low cost,green environmental protection,etc.,the indoor visible light positioning(VLP)technology based on LED has received extensive attention.Current VLP systems are affected by many factors,such as ambient light and fluctuations in LED luminous power.In this paper,an improved VLP system based on channel coding and positioning algorithm is proposed,and an actual positioning system is built to verify the performance.The specific content is as follows:(1)Introduction to the basic theory of indoor visible light positioning system.Firstly,the characteristics of the visible light positioning system are analyzed,including LED characteristics,noise model and channel characteristics.By analyzing the luminous effect and volt-ampere characteristics of the LED,it is found that the light intensity of the LED will fluctuate slightly,and the external circuit needs to provide a stable working current.Then,several commonly used indoor visible light positioning algorithms are introduced,and the principle of geometric measurement method is emphasized.Based on cost,algorithm complexity and accuracy,this paper chooses a positioning algorithm based on Received Signal Strength(RSS).Finally,several technical indicators for evaluating indoor positioning are introduced.(2)Research on improved methods based on channel coding and RSS algorithm.The first is the research based on channel coding,introducing the channel coding module of the Digital video Broadcast-Terrestrial standard(DVB-T)to improve the influence of ambient light in noise.Finally,the LDPC code is selected as the channel coding of the system by comparison,and an improved decoding algorithm is proposed by combining the Log-BP decoding algorithm and the MS decoding algorithm.Secondly,based on the research of the RSS algorithm,it is found that the fluctuation of the LED luminous power affects the Positioning results.A compensation algorithm of adding a fixed detector with a known position is proposed to compensate the fluctuation of the positioning mobile detector,and the feasibility of the algorithm is verified by simulation.(3)Build an experimental platform to verify the improvement of system performance.First complete the hardware design part of the system,implement LDPC coding and decoding on the programmable logic array(FPGA)and carry out functional verification.After that,the design of LED driver circuit and I/V conversion amplifier circuit which can provide stable working current is completed.Finally,an experimental platform with a size of 1m × 1m × 1.5m was built.The experimental results show that the system in this paper has a significant performance improvement compared with the traditional RSS positioning algorithm.The communication distance is increased by about 37% and the communication range is increased by about 262%.And the average error of the traditional RSS algorithm is 12 cm,and the improved system reduces the average error to 5.7cm.