Pressure sensors are the essential equipments in the field of pressure measurement. In this work, we propose a temperature compensation fiber Bragg grating （FBG） pressure sensor based on the plane diaphragm. The pla...Pressure sensors are the essential equipments in the field of pressure measurement. In this work, we propose a temperature compensation fiber Bragg grating （FBG） pressure sensor based on the plane diaphragm. The plane diaphragm and pressure sensitivity FBG （PS FBG） are used as the pressure sensitive components, and the temperature compensation FBG （TC FBG） is used to improve the temperature cross-sensitivity. Mechanical deformation model and deformation characteristics simulation analysis of the diaphragm are presented. The measurement principle and theoretical analysis of the mathematical relationship between the FBG central wavelength shift and pressure of the sensor are introduced. The sensitivity and measure range can be adjusted by utilizing the different materials and sizes of the diaphragm to accommodate different measure environments. The performance experiments are carried out, and the results indicate that the pressure sensitivity of the sensor is 35.7pm/MPa in a range from 0MPa to 50MPa and has good linearity with a linear fitting correlation coefficient of 99.95%. In addition, the sensor has the advantages of low frequency chirp and high stability, which can be used to measure pressure in mining engineering, civil engineering, or other complex environment.展开更多
物联网的快速发展对于无线通信技术提出了更高的要求,专为低带宽、低功耗、远距离、大量连接的物联网应用而设计的低功耗广域网技术( LPWAN: Low Power Wide Area Network)快速兴起。LoRa( Low Power Long Range Transceiver)作为LPWAN...物联网的快速发展对于无线通信技术提出了更高的要求,专为低带宽、低功耗、远距离、大量连接的物联网应用而设计的低功耗广域网技术( LPWAN: Low Power Wide Area Network)快速兴起。LoRa( Low Power Long Range Transceiver)作为LPWAN 技术的典型代表,受到了广泛的关注与研究。本文对于LoRa 的物理层技术体制进行了分析,给出了其基本的数学信号处理模型,提出了基于FFT( Fast Fourier Transform)的信号解调算法,并将该调制解调技术的仿真性能与正交调制非相干检测的理论性能进行了比较,由仿真结果可以看出,两者的性能是一致的。除此之外,分析了LoRa 系统在Guassian 信道及典型衰落信道下的性能表现。展开更多
To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acousti...To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acoustic communications. An FrFD frequency-hopped communication method based on chirp modulation, namely multiple chirp shift keying-FrFD hopping (MCSK-FrFDH), is proposed for underwater acoustic channels. Validated by both simulations and experimental results, this method can reach a bandwidth efficiency twice more than conventional frequency-hopped methods with the same data rate and anti-multipath capability, suggesting that the proposed method achieves a better performance than the traditional frequency hopped communication in underwater acoustic communication channels. Results also show that in practical scenarios, the MCSK-FrFDH system with longer symbol length performs better at the low signal-to-noise ratio (SNR), while the system with larger frequency sweeping range performs better at a high SNR.展开更多
文摘Pressure sensors are the essential equipments in the field of pressure measurement. In this work, we propose a temperature compensation fiber Bragg grating （FBG） pressure sensor based on the plane diaphragm. The plane diaphragm and pressure sensitivity FBG （PS FBG） are used as the pressure sensitive components, and the temperature compensation FBG （TC FBG） is used to improve the temperature cross-sensitivity. Mechanical deformation model and deformation characteristics simulation analysis of the diaphragm are presented. The measurement principle and theoretical analysis of the mathematical relationship between the FBG central wavelength shift and pressure of the sensor are introduced. The sensitivity and measure range can be adjusted by utilizing the different materials and sizes of the diaphragm to accommodate different measure environments. The performance experiments are carried out, and the results indicate that the pressure sensitivity of the sensor is 35.7pm/MPa in a range from 0MPa to 50MPa and has good linearity with a linear fitting correlation coefficient of 99.95%. In addition, the sensor has the advantages of low frequency chirp and high stability, which can be used to measure pressure in mining engineering, civil engineering, or other complex environment.
文摘物联网的快速发展对于无线通信技术提出了更高的要求,专为低带宽、低功耗、远距离、大量连接的物联网应用而设计的低功耗广域网技术( LPWAN: Low Power Wide Area Network)快速兴起。LoRa( Low Power Long Range Transceiver)作为LPWAN 技术的典型代表,受到了广泛的关注与研究。本文对于LoRa 的物理层技术体制进行了分析,给出了其基本的数学信号处理模型,提出了基于FFT( Fast Fourier Transform)的信号解调算法,并将该调制解调技术的仿真性能与正交调制非相干检测的理论性能进行了比较,由仿真结果可以看出,两者的性能是一致的。除此之外,分析了LoRa 系统在Guassian 信道及典型衰落信道下的性能表现。
基金supported by the National Natural Science Foundation of China(4137604041676024)
文摘To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acoustic communications. An FrFD frequency-hopped communication method based on chirp modulation, namely multiple chirp shift keying-FrFD hopping (MCSK-FrFDH), is proposed for underwater acoustic channels. Validated by both simulations and experimental results, this method can reach a bandwidth efficiency twice more than conventional frequency-hopped methods with the same data rate and anti-multipath capability, suggesting that the proposed method achieves a better performance than the traditional frequency hopped communication in underwater acoustic communication channels. Results also show that in practical scenarios, the MCSK-FrFDH system with longer symbol length performs better at the low signal-to-noise ratio (SNR), while the system with larger frequency sweeping range performs better at a high SNR.
