为系统客观地评价某通信系统的抗电磁干扰能力,提出一种以误码率为评价指标的电磁干扰效应实验方法,确定了不同干扰信号对该通信系统的作用规律,分析了干扰机理,结果表明:同频干扰时,在产生误码功率的前2 d Bm,误码率逐渐增大,而后1 d B...为系统客观地评价某通信系统的抗电磁干扰能力,提出一种以误码率为评价指标的电磁干扰效应实验方法,确定了不同干扰信号对该通信系统的作用规律,分析了干扰机理,结果表明:同频干扰时,在产生误码功率的前2 d Bm,误码率逐渐增大,而后1 d Bm范围内,误码率迅速增加到0.47,干扰功率与发射功率呈线性变化;误码率达到10-2数量级,话筒发出吱吱声,达到0.47时显示屏出现死机现象;偏离发射频率2 MHz范围内的信号易产生干扰;带外强干扰信号会使通信系统减敏,干扰功率与信号频偏呈正比;互调干扰的两路信号同步变化时,其功率与发射功率呈线性关系,反之功率与信号频率之间的关系相同;扩频或RS编码可提高通信系统对同频小信号的抑制效果,而对邻频干扰,扩频反而使系统更易受到干扰,且产生干扰的功率区间变宽。展开更多
The Chinese government is dedicated to enhancing the level of informatization in administrative law enforcement to ensure fairness and increase credibility.Currently,law enforcement has exposed such problems as insuff...The Chinese government is dedicated to enhancing the level of informatization in administrative law enforcement to ensure fairness and increase credibility.Currently,law enforcement has exposed such problems as insufficient force,difficulties in collecting evidence,and low evidential power.These problems contradict the principles of rule of law and standardization.Many local governments have implemented advanced information technologies for urban administration and law enforcement,including big data,artificial intelligence,and IoT.Among these technologies,IoT is the core communication infrastructure for innovative law enforcement platforms.However,traditional video communications rely on batteries or dedicated power sources,leading to maintenance challenges and high power consumption.In this paper,we propose AT-Eye,a new video communication paradigm for all-time law enforcement video monitoring,which is battery-free and high-throughput.The key enabler of AT-Eye is ambient backscatter technology,which enables energy harvesting and video communication simultaneously.Unlike previous methods,our proposal introduces a novel CCK-based modulation for tag cameras and achieves 4-way concurrency.The modulation is simple because it uses phase difference and it is energyefficient because generating square waves is adequate.Moreover,to ensure full compatibility with COTS WiFi,we modulate the physical service data unit.Therefore,data recovery is possible using only commercial NICs.We conduct comprehensive experiments to examine our proposal and experiment results show that AT-Eye achieves a throughput of 10.8 Mbps with COTS radios.We also simulate a 16-way battery-free tag camera system,demonstrating AT-Eye’s feasibility of high-definition video communication.展开更多
文摘为系统客观地评价某通信系统的抗电磁干扰能力,提出一种以误码率为评价指标的电磁干扰效应实验方法,确定了不同干扰信号对该通信系统的作用规律,分析了干扰机理,结果表明:同频干扰时,在产生误码功率的前2 d Bm,误码率逐渐增大,而后1 d Bm范围内,误码率迅速增加到0.47,干扰功率与发射功率呈线性变化;误码率达到10-2数量级,话筒发出吱吱声,达到0.47时显示屏出现死机现象;偏离发射频率2 MHz范围内的信号易产生干扰;带外强干扰信号会使通信系统减敏,干扰功率与信号频偏呈正比;互调干扰的两路信号同步变化时,其功率与发射功率呈线性关系,反之功率与信号频率之间的关系相同;扩频或RS编码可提高通信系统对同频小信号的抑制效果,而对邻频干扰,扩频反而使系统更易受到干扰,且产生干扰的功率区间变宽。
基金This work was supported by NSFC Grant No.62276244,61932017,and 61971390.
文摘The Chinese government is dedicated to enhancing the level of informatization in administrative law enforcement to ensure fairness and increase credibility.Currently,law enforcement has exposed such problems as insufficient force,difficulties in collecting evidence,and low evidential power.These problems contradict the principles of rule of law and standardization.Many local governments have implemented advanced information technologies for urban administration and law enforcement,including big data,artificial intelligence,and IoT.Among these technologies,IoT is the core communication infrastructure for innovative law enforcement platforms.However,traditional video communications rely on batteries or dedicated power sources,leading to maintenance challenges and high power consumption.In this paper,we propose AT-Eye,a new video communication paradigm for all-time law enforcement video monitoring,which is battery-free and high-throughput.The key enabler of AT-Eye is ambient backscatter technology,which enables energy harvesting and video communication simultaneously.Unlike previous methods,our proposal introduces a novel CCK-based modulation for tag cameras and achieves 4-way concurrency.The modulation is simple because it uses phase difference and it is energyefficient because generating square waves is adequate.Moreover,to ensure full compatibility with COTS WiFi,we modulate the physical service data unit.Therefore,data recovery is possible using only commercial NICs.We conduct comprehensive experiments to examine our proposal and experiment results show that AT-Eye achieves a throughput of 10.8 Mbps with COTS radios.We also simulate a 16-way battery-free tag camera system,demonstrating AT-Eye’s feasibility of high-definition video communication.
