A novel design and implementation of an attendance checking node for coal mines based on the CAN bus is presented in this paper. Hardware circuits and programming methods for the attendance checking node are discussed...A novel design and implementation of an attendance checking node for coal mines based on the CAN bus is presented in this paper. Hardware circuits and programming methods for the attendance checking node are discussed,including the single-chip computer with CAN controller AT89C51CC03,the CAN bus transceiver TJA1050,the large capacity DataFlash memory,the real-time clock DS1302,the voice chip ISD2560 and the card-reading circuit in Wie-gand format. All the extended hardware satisfies the requirements for intrinsically safe circuits (GB3836.4-2000) and intrinsically safe authentication promoted by the national explosion-proof institute. Further,the software programming methods for the CAN controller (AT89C51CC03) and the implementation of the CAN communications protocol are presented as well.展开更多
光通信系统中低密度奇偶校验(Low-density Parity-check,LDPC)码采用对数似然比置信传播(Log-likelihood Ratio Belief Propagation,LLR-BP)算法进行译码时,在高信噪比区域迭代译码过程中会出现变量节点外部信息振荡不收敛而导致译码纠...光通信系统中低密度奇偶校验(Low-density Parity-check,LDPC)码采用对数似然比置信传播(Log-likelihood Ratio Belief Propagation,LLR-BP)算法进行译码时,在高信噪比区域迭代译码过程中会出现变量节点外部信息振荡不收敛而导致译码纠错性能的降低。为满足光通信系统的要求,提出了一种削弱外部消息振荡的改进LLR-BP译码算法。该算法通过引入加权系数平衡前后两次迭代之间变量节点传递的外部信息,明显减缓了外部信息的振荡现象。仿真结果表明:与传统LLR-BP译码算法相比,该改进LLR-BP算法具有更佳的误码性能,同时降低变量节点外部信息振荡现象并加快了译码的收敛速度。展开更多
针对串行抵消列表翻转(Successive Cancellation List Flip,SCLF)译码算法存在译码性能与复杂度不能同时兼顾的问题,提出了一种快速串行抵消列表翻转(Fast Successive Cancellation List Flip,FSCLF)译码算法。该算法通过加入四种特殊...针对串行抵消列表翻转(Successive Cancellation List Flip,SCLF)译码算法存在译码性能与复杂度不能同时兼顾的问题,提出了一种快速串行抵消列表翻转(Fast Successive Cancellation List Flip,FSCLF)译码算法。该算法通过加入四种特殊结点的识别来加快译码速率,同时构建了临界集(Critical Set,CS),不再依据先前译码错误而引起的错误传播,而是通过两种特殊结点即信息比特R1结点和单奇偶校验(Single-Parity-Check,SPC)结点分别对对数似然比(LogLikelihood Ratio,LLR)值进行计算来判决并确定翻转位置,当奇偶校验位不满足时只需翻转与最不可靠输入LLR值相对应的信息比特,这样减少了翻转次数,从而降低了算法复杂度。仿真结果表明:在误块率为10-5时,所提出的FSCLF译码算法比原SCLF译码算法的信噪比改善了0.09dB,为中短码长情况提供了参考算法。展开更多
针对无线传感器网络的最小二乘定位算法抗差性的不足,提出了一种基于时空滤波(STF)的抗差性加权最小二乘(WLS)节点定位算法——STLS。该算法基于空间域滤波的数据一致性检测算法利用相邻节点间必须满足的几何约束关系,采用优化矩阵操作...针对无线传感器网络的最小二乘定位算法抗差性的不足,提出了一种基于时空滤波(STF)的抗差性加权最小二乘(WLS)节点定位算法——STLS。该算法基于空间域滤波的数据一致性检测算法利用相邻节点间必须满足的几何约束关系,采用优化矩阵操作,剔除粗差邻居节点,其计算复杂度为多项式的平方。通过使用具有2步收敛特性的 DFP算法,最小化目标代价函数,实现节点的快速定位。实验结果表明,在均匀网格拓扑或各向异性 C 型网格拓扑下,该算法均可有效识别和剔除测距低估粗差点,其定位精度明显优于未进行空间一致性检测的加权最小二乘定位算法,当网络平均连通度较低时,该优势表现得尤为明显。展开更多
基金Projects 50674086 supported by the National Natural Science Foundation of ChinaBS2006002 by the Society Development Science and Technology Planof Jiangsu Province20060290508 by the Doctoral Foundation of Ministry of Education of China
文摘A novel design and implementation of an attendance checking node for coal mines based on the CAN bus is presented in this paper. Hardware circuits and programming methods for the attendance checking node are discussed,including the single-chip computer with CAN controller AT89C51CC03,the CAN bus transceiver TJA1050,the large capacity DataFlash memory,the real-time clock DS1302,the voice chip ISD2560 and the card-reading circuit in Wie-gand format. All the extended hardware satisfies the requirements for intrinsically safe circuits (GB3836.4-2000) and intrinsically safe authentication promoted by the national explosion-proof institute. Further,the software programming methods for the CAN controller (AT89C51CC03) and the implementation of the CAN communications protocol are presented as well.
文摘光通信系统中低密度奇偶校验(Low-density Parity-check,LDPC)码采用对数似然比置信传播(Log-likelihood Ratio Belief Propagation,LLR-BP)算法进行译码时,在高信噪比区域迭代译码过程中会出现变量节点外部信息振荡不收敛而导致译码纠错性能的降低。为满足光通信系统的要求,提出了一种削弱外部消息振荡的改进LLR-BP译码算法。该算法通过引入加权系数平衡前后两次迭代之间变量节点传递的外部信息,明显减缓了外部信息的振荡现象。仿真结果表明:与传统LLR-BP译码算法相比,该改进LLR-BP算法具有更佳的误码性能,同时降低变量节点外部信息振荡现象并加快了译码的收敛速度。
文摘针对串行抵消列表翻转(Successive Cancellation List Flip,SCLF)译码算法存在译码性能与复杂度不能同时兼顾的问题,提出了一种快速串行抵消列表翻转(Fast Successive Cancellation List Flip,FSCLF)译码算法。该算法通过加入四种特殊结点的识别来加快译码速率,同时构建了临界集(Critical Set,CS),不再依据先前译码错误而引起的错误传播,而是通过两种特殊结点即信息比特R1结点和单奇偶校验(Single-Parity-Check,SPC)结点分别对对数似然比(LogLikelihood Ratio,LLR)值进行计算来判决并确定翻转位置,当奇偶校验位不满足时只需翻转与最不可靠输入LLR值相对应的信息比特,这样减少了翻转次数,从而降低了算法复杂度。仿真结果表明:在误块率为10-5时,所提出的FSCLF译码算法比原SCLF译码算法的信噪比改善了0.09dB,为中短码长情况提供了参考算法。
文摘针对无线传感器网络的最小二乘定位算法抗差性的不足,提出了一种基于时空滤波(STF)的抗差性加权最小二乘(WLS)节点定位算法——STLS。该算法基于空间域滤波的数据一致性检测算法利用相邻节点间必须满足的几何约束关系,采用优化矩阵操作,剔除粗差邻居节点,其计算复杂度为多项式的平方。通过使用具有2步收敛特性的 DFP算法,最小化目标代价函数,实现节点的快速定位。实验结果表明,在均匀网格拓扑或各向异性 C 型网格拓扑下,该算法均可有效识别和剔除测距低估粗差点,其定位精度明显优于未进行空间一致性检测的加权最小二乘定位算法,当网络平均连通度较低时,该优势表现得尤为明显。