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本文提出了一种跳频/多载波频率分集/扩频多址(FH/MCFD/SSMA)无线通信系统,给出了FH/MCFD/SSMA系统的发送和接收模型,对判惟变量统计特性进行了分析,然后对峰窝系统反向链路在理想定时和信道估计条件下用户平均接收误码率进行了仿真。结果表明,FH/MCFD/SSMA蜂窝通信系统具有较好的抗多径衰落能力,同单载波FH/SSMA系统相比其误码性能和频谱效率有显著改善。 相似文献
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高速跳频系统中的DSP 总被引:1,自引:0,他引:1
高速的跳频系统以其优良的抗干扰,保密特性已经被广泛地应用于军事,民用的各个领域。在这种系统中,数据的处理速率是实现的关键。本文介绍了德州仪器(TI)的高速定点DSP──TMS320C54X在高速跳频系统中的应用。跳频系统的原理跳频扩展频谱通信系统是将可用的信道带宽分割成大量相邻的信道(频隙)。用户信号每隔一定时间就转换一次信道,该时间就称为切普时间间隔(chipinterval),跳频速率(frequency-hoppingrate)就定义为切普时间间隔的倒数。也就是说,用户信号的载波每隔一定时… 相似文献
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提出了一种计算机构成FH/DS系统中DDS跳频率合成器的方法,讨论了方案的理论基础,给出了方案的软硬件具体实施步骤,直扩码和跳频图案的计算机设计特点,以及性能的分析。 相似文献
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本文根据跳频通信的基本原理,设计出一种基于通用DSP芯片TMS320C51的跳频通信系统同波段转发器相互交链的并对伪随机码的产生和跳频调制方式作了简要分析。 相似文献
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用于跳频码分多址通信的混沌跳频序列 总被引:36,自引:2,他引:34
最近提出的混沌跳频序列具有均匀性、保密性好的优点,但存在较大的汉明相关值,本文给出了一种减小混沌跳频序列汉明相关值的方法,该方法的构造的跳频序列是帆努利随机序列,汉明相关函数服从Poisson分布,在跳频码分多址(FH/CDMA)系统中,,这种混沌跞频序列的系统容量与常规跳频序列基本相同。 相似文献
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一种新的短波数传调制体制 总被引:1,自引:0,他引:1
本文提出一种利用短波信道传输数据时能够抗衰落抗多径的新方案——多频相位组合编码结合跳频(MFPCC/FH),讨论了MFPCC/FH编码原理和性能,介绍了MFPCC/FH调制解调器的实现方法。 相似文献
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本文阐述了跳频扩频的基本原理,进而提出了一种利用直接数字频率合成(DDS)实现CDMA/FH的方法,最后给出了实验电路及测试结果 相似文献
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介绍了利用DDS-PLL组成方案来实现快速跳频的原理和它的性能,并通过实验证明它是一种性能良好、实际可行的快速跳频方案。 相似文献
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通过对CHESS信号结构及特点的介绍,分析了对CHESS信号侦察和干扰的可行性及策略.提出了一种CHESS信号侦察干扰机的初步实现方案。 相似文献
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Gustafson DH Hawkins R McTavish F Pingree S Chen WC Volrathongchai K Stengle W Stewart JA Serlin RC 《The Journal of communication》2008,58(2):238-257
To compare the benefits of the Internet generally versus a focused system of services, 257 breast cancer patients were randomly assigned to a control group, access to the Internet with links to high-quality breast cancer sites, or access to an eHealth system (Comprehensive Health Enhancement Support System, CHESS) that integrated information, support, and decision and analysis tools. The intervention lasted 5 months, and self-report data on quality of life, health-care competence, and social support were collected at pretest and at 2-, 4-, and 9-month posttests. CHESS subjects logged on more overall than Internet subjects and accessed more health resources, but the latter used non health-related sites more. Subjects with access to the Internet alone experienced no better outcomes than controls at any of the 3 time points, compared to pretest levels. Subjects with CHESS experienced greater social support during the intervention period and had higher scores on all 3 outcomes at 9 months, 4 months after the intervention ended. CHESS subjects also scored higher than those with Internet access during the intervention period but not significantly after the intervention ended. Thus, CHESS (with one simple interface and integrated information, communication, and skills services) helped newly diagnosed breast cancer patients even after computers were removed. In contrast, patients received little benefit from Internet access, despite having links to a variety of high-quality sites. 相似文献
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Alon SlapakArie Yeredor 《Signal processing》2011,91(8):2016-2027
The CHaracteristic-function-Enabled Source Separation (CHESS) method for independent component analysis (ICA) is based on approximate joint diagonalization (AJD) of Hessians of the observations' empirical log-characteristic-function, taken at selected off-origin “processing points”. As previously observed in other contexts, the AJD performance can be significantly improved by optimal weighting, using the inverse of the covariance matrix of all of the off-diagonal terms of the target-matrices. Fortunately, this apparently cumbersome weighting scheme takes a convenient form under the assumption that the mixture is already “nearly separated”, e.g., following some initial separation. We derive covariance expressions for the Sample-Hessian matrices, and show that under the near-separation assumption, the weight matrix takes a nearly block-diagonal form, conveniently exploited by the recently proposed WEighted Diagonalization using Gauss itErations (WEDGE) algorithm for weighted AJD. Using our expressions, the weight matrix can be estimated directly from the data—leading to our WeIghTed CHESS (WITCHESS) algorithm. Simulation results demonstrate how WITCHESS can lead to significant performance improvement, not only over unweighted CHESS, but also over other ICA methods. 相似文献
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差分跳频是CHESS电台的核心技术,它主要归结于一种C函数算法,这种函数集跳频图案和信息调制于一体。文中介绍了差分跳频的基本原理,G函数以及G函数的算法原理和构造方法,分析了G函数跳频图案的性能,并对其进行了检验。结果表明,该算法产生的跳频图案具有良好的随机性和均匀性。 相似文献
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CHESS系统的跳频通信技术 总被引:4,自引:0,他引:4
文章以LockheedSanders公司的CHESS(CorrelatedHoppingEnhancedSpreadSpectrumk增强型相关跳频扩频)系统为例,介绍了用于HF跳频通信的差分跳频(DFH)、DSP等技术。 相似文献
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本文介绍一个比较适用化而硬件又适合于LSI芯片设计的实时孤立单词语音识别接口的设计,该接口用带通滤波器组的方法提取语音特征,用分块四值化方法压缩数据,用最小距离法进行识别. 相似文献