Research on Channel Coding in Underwater Acoustic Communication Combined with OFDM Technology

正交频分复用（OFDM）技术是一种多载波数字调制技术，它是一种实现高速无线数据通信的良好方法。在无线通信领域中，OFDM技术得到广泛的应用并成为第三代移动通信的主流技术。然而，将OFDM技术应用于水声通信中，在国内的研究尚处于起步阶段。水声信道是一个极其复杂的时间－频率－空间变化，强多径干扰，带宽有限且噪声干扰严重的信道，在这样的信道环境下实现通信系统的高速、可靠传输是极具挑战性的。OFDM系统中插入保护间隔后，若符号定时同步的起始时刻落在保护间隔内，则可以避免ISI并减小ICI，然而，OFDM技术对信道平坦性衰落却不能很好地克服，也就是说，信号经过水声信道的传输后，各子载波的幅度仍然会产生服...Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier digital modulation technique, which proved to be a good method for high-speed wireless data communications. In wireless communications domain, OFDM has been used widely and becomes the mainstream technique for the 3rd Generation mobile communications. However, it is just at the beginning to apply OFDM to underwater acoustic commu...学位：工程硕士院系专业：计算机与信息工程学院_通信与信息系统学号：20023002

基于DSP6711 的O FDM 技术编解码实现

基于浮点数字信号处理芯片DSP6711, 采用软件无线电方法构建一个基本的O FDM 通信系统。在用 MA TLAB 语言对该通信系统进行仿真的基础上, 完成了CCS2. 1 软件平台上的由DSP 硬件组成的O FDM 系统C 语言编程和运行通过; 并利用M at lab 所建立的仿真信道对此O FDM 系统的编解码性能进行了测试。结果表明, 论 文所建立的编解码实现方案对高斯衰落信道具有一定的对抗性。国家自然科学基金项

分布式节能灯功率自动检测系统的设计与实现

　介绍了一个基于单片机和可视Basic 语言(VB) 的节能灯功率自动检测系统,用于节能 灯生产线上对生产的产品进行测试,检验是否合格。系统通过单片机完成被测灯的开关切换功能以 及与PC 机进行通信,而PC 机接收来自功率计的测试数据并将其存储在数据库中,以便查询。文中详 细介绍了系统的硬件组成和软件设计

The Implementation of the Encoding and Decoding OFDM Technique Based on DSP6711

基于浮点数字信号处理芯片DSP6711,采用软件无线电方法构建一个基本的OFDM通信系统。在用MATLAB语言对该通信系统进行仿真的基础上,完成了CCS2.1软件平台上的由DSP硬件组成的OFDM系统C语言编程和运行通过;并利用Matlab所建立的仿真信道对此OFDM系统的编解码性能进行了测试。结果表明,论文所建立的编解码实现方案对高斯衰落信道具有一定的对抗性。Adopting the idea of the software radio, the article designs an OFDM communication system implemented by floating dot digital signal processing chip DSP6711.Basing on the result of the simulation of this system with MATLAB, the author implemented the OFDM communication system with DSP hardware, using C language of the professional software CCS2.1. In addition, the author test the performance of the encoding & decoding of the OFDM communication system by utilizing the channel simulated with MATLAB. The results indicate that the encoding & decoding scheme designed in the article possesses the fine performance of antagonism to Gauss's Fading Channel.国家自然科学基金项目(60272028

The OFDM-Based Study of Error Correcting Coding in Underwater Acoustical Channel

仿真分析了在水声信道下编码正交频分复用(COFDM)系统中,由于采用不同的纠错编码方法所产生的性能差异的原因,并给出了在构建高性能COFDM水声通信系统时选择纠错编码参数的原则.为了构建实用高效水声COFDM通信系统,本文分析了算法复杂度从易到难的几种纠错编码方法、卷积码、RS码、RS+卷积的级联码和Turbo码.对它们的码率、码长、生成多项式以及是否交织及交织深度等因素对系统复杂性以及系统性能的影响进行了全面的比较和论述.最后,仿真实验验证了在水声COFDM通信系统中,通过选择合适的参数,能够找到复杂度低但性能优良的级联码,其性能可以和复杂度较高的Turbo码相媲美.This paper simulated the under water acoustic communication system based on COFDM and analyzed the reasons of different performances caused by different error-correcting codes. And this paper also put forward the parameter selection principle of error-correcting code. To build practical and high performance COFDM system,this paper analyzed the error-correcting codes from low complexion to relatively high complexion,such as,convolutional code ,RS code ,serial concatenated code of RS code plus convolutional code and turbo code. The parameters of code rate,code length,generation polynomial, interweaving or not and interweaving matrix length are all considerated and analyzed elaborately. Finally,the simulating experiments proved that there are some relatively lower complexion systems based on serial concatenated codes of RS code plus convolutional code that are able to gain similar good performance as the systems based on turbo code.国家自然科学基金(60572106,60772141);; 985二期创新平台资

Influence of Water and Fertilizer Coupling on Photosynthetic Characters and Yield of Pumpkin In Loess Plateau

通过不同的灌水和施肥处理,研究水肥交互作用对南瓜光合特性日变化及产量的影响,结果表明:水分与施肥因子对南瓜叶片的光合特性和产量有重要影响,在水分胁迫的情况下,肥水交互作用不显著,在水分较低的情况下,二者表现互为限制条件的协同作用;在水分较高的情况下,肥水交互作用转变成顺序加和作用。其中单因素效应大小表现为:氮>水>磷,耦合效应大小表现为:氮与水耦合>氮与磷耦合>磷与水耦合。在水分适宜时,适宜的施肥量(施氮量50kg/hm2、施磷量35 kg/hm2)可以提高南瓜光合速率和产量,不施肥或施肥量过高都会影响南瓜光合速率和产量

Optimum fertilization for high-sugar and low-nitrate pumpkin production in the Loess Plateau

采用N、P、K3因素最优设计,在陕北黄土高原进行了南瓜氮、磷、钾用量及其肥效反应模式田间试验,研究不同施肥量对南瓜硝态氮、可溶性糖两项营养品质的影响,旨在探讨南瓜品质高糖低硝酸盐的N、P、K肥效反应模式,提出优化的施肥方案。结果表明,N肥单因素对南瓜硝态氮和可溶性糖含量影响最大,K肥单因素对南瓜硝态氮和可溶性糖含量影响不显著,N与P交互作用对南瓜高糖低硝酸盐影响显著,K肥施用量一定时,氮肥与磷肥的施用量不易过大。根据南瓜N、P、K肥效反应模式,筛选出南瓜品质硝态氮含量在200mg·kg-1以下、可溶性糖含量在7%以上的较佳施肥量为施氮95～120 kg·hm-2,施磷40～70 kg·hm-2,施钾35～80 kg·hm-2,N∶P2O5∶K2O=1∶0.42∶0.37

Combining mPEG-Hz Derivatization and Filter-Based Size Exclusion for Selective Enrichment of N-glycopeptides

Although hydrazide (Hz) is widely used for the selective enrichment of N-glycopeptides, it takes a long time to wash off the non-specifically adsorbed peptides on the Hz beads. To solve this problem, in our recent work, a strategy with the combination of methoxy-polyethylene glycol (mPEG)-Hz based derivatization and filter-based size exclusion, was developed, and successfully applied for the facile enrichment of N-glycopeptides. Herein, glycoproteins were first digested, followed by the oxidization of the cis-diol groups of carbohydrates on glycopeptides to aldehydes, which could further form covalent hydrazone bonds with mPEG-Hz. With the increased molecular weights, the derivatized glycopeptides could be separated from other peptides by a centrifugal filter device. After that, PNGase F was added to cut off mPEG-conjugated carbohydrates, which could be kept in the retentate, while the released peptides could be collected in filtrate after centrifuge. HRP, a standard glycoprotein, was used to evaluate this protocol. With 10-kDa mPEG-Hz for N-glycopeptide enrichment, and filter devices with nominal molecular weight limit of 10 kDa to removal non-glycopeptides, 5 peptides with N-glycosite were detected, with the specificity consistent to that obtained with the commercial hydrazide beads. Most importantly, the removal of non-glycopeptides became easy by filter-based size exclusion, beneficial to shorten the sample preparation time. With the further optimization of the size of mPEG-Hz and the cut off molecular weight of filter, improved selectivity of glycopeptide enrichment is expected to achieve, which might be promising in N-glycoproteome analysis.Although hydrazide (Hz) is widely used for the selective enrichment of N-glycopeptides, it takes a long time to wash off the non-specifically adsorbed peptides on the Hz beads. To solve this problem, in our recent work, a strategy with the combination of methoxy-polyethylene glycol (mPEG)-Hz based derivatization and filter-based size exclusion, was developed, and successfully applied for the facile enrichment of N-glycopeptides. Herein, glycoproteins were first digested, followed by the oxidization of the cis-diol groups of carbohydrates on glycopeptides to aldehydes, which could further form covalent hydrazone bonds with mPEG-Hz. With the increased molecular weights, the derivatized glycopeptides could be separated from other peptides by a centrifugal filter device. After that, PNGase F was added to cut off mPEG-conjugated carbohydrates, which could be kept in the retentate, while the released peptides could be collected in filtrate after centrifuge. HRP, a standard glycoprotein, was used to evaluate this protocol. With 10-kDa mPEG-Hz for N-glycopeptide enrichment, and filter devices with nominal molecular weight limit of 10 kDa to removal non-glycopeptides, 5 peptides with N-glycosite were detected, with the specificity consistent to that obtained with the commercial hydrazide beads. Most importantly, the removal of non-glycopeptides became easy by filter-based size exclusion, beneficial to shorten the sample preparation time. With the further optimization of the size of mPEG-Hz and the cut off molecular weight of filter, improved selectivity of glycopeptide enrichment is expected to achieve, which might be promising in N-glycoproteome analysis