从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法。该方法在APD接收机输出统计模型（Webb-Gaussian模型）的基础上,推导了M-PPM的LDPC译码算法...从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法。该方法在APD接收机输出统计模型（Webb-Gaussian模型）的基础上,推导了M-PPM的LDPC译码算法中初始似然比值的精确计算方法,并给出了详细的译码过程。理论分析和仿真结果表明,与目前普遍采用的APD近似非对称Gaussian统计模型下的译码性能相比较,在相同的信道条件下,该方法可以获得大约1~2 d B的性能增益。这为进一步提高自由空间光通信系统的性能提供了一定的理论依据。展开更多
In the methanolic solution, the selectivity of rhodamine hydrazide （RhH） was simply switched from Cu2＋ to Hg2＋ ions. For the optimal absorption of RhH onto a solid-phase membrane, pure methanol was used to dissolv...In the methanolic solution, the selectivity of rhodamine hydrazide （RhH） was simply switched from Cu2＋ to Hg2＋ ions. For the optimal absorption of RhH onto a solid-phase membrane, pure methanol was used to dissolve RhH prior to the impregnation. Of solid-phase membranes tested, the filter paper was chosen due to its cost-effectiveness and good detection limit of Hg2＋ ion. The detection limit of the RhH impregnated filter paper for the detection of Hg2＋ ion was determined to be under 2 ppm both fluorescent and colorimetric detection.展开更多
文摘从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法。该方法在APD接收机输出统计模型（Webb-Gaussian模型）的基础上,推导了M-PPM的LDPC译码算法中初始似然比值的精确计算方法,并给出了详细的译码过程。理论分析和仿真结果表明,与目前普遍采用的APD近似非对称Gaussian统计模型下的译码性能相比较,在相同的信道条件下,该方法可以获得大约1~2 d B的性能增益。这为进一步提高自由空间光通信系统的性能提供了一定的理论依据。
文摘In the methanolic solution, the selectivity of rhodamine hydrazide （RhH） was simply switched from Cu2＋ to Hg2＋ ions. For the optimal absorption of RhH onto a solid-phase membrane, pure methanol was used to dissolve RhH prior to the impregnation. Of solid-phase membranes tested, the filter paper was chosen due to its cost-effectiveness and good detection limit of Hg2＋ ion. The detection limit of the RhH impregnated filter paper for the detection of Hg2＋ ion was determined to be under 2 ppm both fluorescent and colorimetric detection.
