Research And Design Of High Precision Angle Sensing System Toward LPWAN

In the era of industry 4.0,the demand for long-distance low-power angle sensor is increasingly strong.It is urgent to have a reliable and high-precision angle sensor system that can meet the demand of low-power wireless long-range communication.Combining low power wide area network(LPWAN)technology with angle sensor technology to design a wireless angle sensing information collection system meets the needs of social economy and development,which has important practical significance.This paper is oriented to the problem of decreased data reliability due to low power consumption and long-distance transmission of LPWAN technology.With the goal of achieving high-precision angle sensing acquisition,processing and effective transmission,this paper proposes and constructs a high-precision angle sensing system for LPWAN.The angle sensing system designed in this paper mainly includes three modules,among which the multi-mode high-precision calculation module combined with the deployment method can provide up to 17-bit resolution angle analysis;The high reliability wireless transmission module based on the calculation module can suppress the phase offset error within 0.3 rad for accurate demodulation.The channel coding and decoding module with strong error correction ability can suppress the bit error rate of wireless transmission below 10^-3 when the signal to noise ratio is higher than 2.5d B.The main research results of this article are as follows:1.Aiming at the problems of external interference and quantization noise in the generation of angle sensing signals,and facing the need to improve resolution,a high-resolution combined signal acquisition device for suppressing interference and noise is designed,which has superior signal acquisition capabilities.2.Aiming at the high-precision processing requirements of angle sensing signals and the phase calculation requirements required in the modulation and demodulation process,a multi-mode high-precision calculation algorithm is proposed and designed.Among them,the inverse triangulation calculation error is less than 10^-3 rad,combined with the designed information acquisition device It can provide data output with a resolution of up to 17 bits for angle sensing.At the same time,it can also provide phase amplitude calculation with an error of less than 10^-3 for transmission modulation.The calculation is accurate and the hardware implementation is less difficult.3.Facing the low power consumption and long-distance transmission requirements of LPWAN and the problem of frequency band congestion,a variety of modulation and demodulation methods are modeled and simulated in the frequency band below 1GHz,and the PSK modulation and demodulation scheme is selected to design a highly reliable wireless transmission module;The quadrature modulation and transmission algorithm is proposed and designed to improve the spectrum utilization.Based on the high-precision integrated calculation module,two-stage carrier synchronization and timing recovery algorithm are designed,the demodulation phase deviation is less than 0.3 rad,carrier frequency and phase offset suppression capabilities are excellent.4.In order to solve the problem of data distortion caused by bit error in low-power long-distance transmission,low density parity check(LDPC)is proposed based on the analysis and optimization of LDPC algorithm,an optimization algorithm based on quasi cyclic structure is proposed and designed.By using the structural characteristics of the double diagonal structure matrix,the matrix multiplication operation in coding is simplified,and the process of calculating and generating matrix is omitted,so as to reduce the storage requirements and optimize the coding speed.5.Optimize and simulate the decoding error correction algorithm with different information as the decision factor,and design an improved minimum sum product error correction algorithm based on the error correction capability and the algorithm complexity and error correction calculation delay.Combining the LDPC codec algorithm proposed and designed in this paper with the wireless transmission algorithm,when the bit error rate is less than10^-3,the QPSK modulation signal-to-noise ratio threshold is only 5.1d B,and the BPSK modulation signal-to-noise ratio threshold is only 2.5d B;that is,under relatively low signal transmission power,reliable data transmission can be guaranteed.Finally,the register transfer level(RTL)circuit of each part of the algorithm is designed and simulated by Quartus prime development kit.The results show that the function of the designed circuit is consistent with the algorithm design,and the performance is excellent,which meets the design expectation of this paper.