针对通信系统解调损失测试过程中存在的引用理论误码率不准确以及保证置信度情况下的码元测试长度的标准不一问题,对部分常引用错误的调制体制的理论误码率进行了推导分析,对误码率测试长度与置信度之间的关系进行分析计算,得到在置信度...针对通信系统解调损失测试过程中存在的引用理论误码率不准确以及保证置信度情况下的码元测试长度的标准不一问题,对部分常引用错误的调制体制的理论误码率进行了推导分析,对误码率测试长度与置信度之间的关系进行分析计算,得到在置信度0.99情况下码元测试长度应不小于136/Pe(Pe为系统的误码率上限)。开展了验证实验,实验数据表明,错误的引用BPSK以及CPFSK(非相干解调)的理论误码率将引起解调损失误差分别不小于0.7 d B和1.0 d B;相对于136/Pe的码元测试长度下的解调损失的重复性为0.08 d B,10/Pe的码元测试长度下的解调损失的重复性增大了4倍。展开更多
The microstructure and mechanical properties of AZ80 magnesium alloy after solid solution and aging treatments were studied by using optical microscope （OM）, X-ray diffraction （XRD）, scanning electron microscopy ...The microstructure and mechanical properties of AZ80 magnesium alloy after solid solution and aging treatments were studied by using optical microscope （OM）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） as well as tensile testing. The results indicated that β-Mg17Al12 phase was getting to distribute discontinuously along the grain boundary after treated at 395℃ ageing for 12 h followed by water-cooling, but it did not dissolve into α-Mg completely. The residualβ-Mg17Al12 phase distributed along the grain boundary and had block-like or island shapes. The size of α-Mg was getting to be coarsening but not significantly. The β-Mg17Al12 precipitates appeared in discontinuous and continuous pattems from supersaturated α-Mg solid solution after aged at 200℃. The precipitation patterns were associated with the aging time essentially. The tensile strength and elongation of the alloy increased significantly but the hardness and yield strength decreased after solid solution treatment. However, with the prolonging of aging time, the hardness and strength of alloy increased while the ductility decreased.展开更多
文摘针对通信系统解调损失测试过程中存在的引用理论误码率不准确以及保证置信度情况下的码元测试长度的标准不一问题,对部分常引用错误的调制体制的理论误码率进行了推导分析,对误码率测试长度与置信度之间的关系进行分析计算,得到在置信度0.99情况下码元测试长度应不小于136/Pe(Pe为系统的误码率上限)。开展了验证实验,实验数据表明,错误的引用BPSK以及CPFSK(非相干解调)的理论误码率将引起解调损失误差分别不小于0.7 d B和1.0 d B;相对于136/Pe的码元测试长度下的解调损失的重复性为0.08 d B,10/Pe的码元测试长度下的解调损失的重复性增大了4倍。
文摘The microstructure and mechanical properties of AZ80 magnesium alloy after solid solution and aging treatments were studied by using optical microscope （OM）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） as well as tensile testing. The results indicated that β-Mg17Al12 phase was getting to distribute discontinuously along the grain boundary after treated at 395℃ ageing for 12 h followed by water-cooling, but it did not dissolve into α-Mg completely. The residualβ-Mg17Al12 phase distributed along the grain boundary and had block-like or island shapes. The size of α-Mg was getting to be coarsening but not significantly. The β-Mg17Al12 precipitates appeared in discontinuous and continuous pattems from supersaturated α-Mg solid solution after aged at 200℃. The precipitation patterns were associated with the aging time essentially. The tensile strength and elongation of the alloy increased significantly but the hardness and yield strength decreased after solid solution treatment. However, with the prolonging of aging time, the hardness and strength of alloy increased while the ductility decreased.
