共查询到20条相似文献,搜索用时 125 毫秒
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一种新型的帧同步码组:超巴克码 总被引:1,自引:1,他引:0
本文分析了数字传输系统中的假帧同步概率和假帧同步频数,导出了较为严密的假帧同步频数计算公式,提出了与一般不同的判别帧同步码组性能的理想曲线。在此基础上,向读者推荐一种新型的帧同步码组——SB码(超巴克码)。用它作帧同步码组时,性能优于巴克码。 相似文献
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针对AOS协议中卫星自适应帧的帧同步码识别问题,在对传统的自相关算法进行研究的基础上,提出了一种改进的自相关算法进行分析和识别。该方法克服了传统自相关算法极易受到非同步码影响的缺点。首先对数据进行运算识别出帧长和同步码长,然后通过得到的帧长和同步码长计算出同步码起始位。仿真实验表明:该方法能够利用较少的数据快速准确地识别出帧同步码,并具有良好的容错性能。 相似文献
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本文针对协议类型未知条件下集中插入式帧同步的盲识别问题,首次提出了一种基于离散度分析的快速帧同步盲识别算法。首先,根据集中插入式帧同步的特点,通过分析比较同步码和帧内其他序列的相关性,得出集中插入式同步码都具有很小的相关旁瓣的结论;然后,根据离散度分析理论,通过计算序列的相对离散度值分析序列的相关性,利用上述方法对待识别数据进行循环切分并计算每个切分段的相对离散度值,达到准确切分帧同步码的目的;最后,通过分析各子切分序列的相对离散度值,实现同步码的准确识别。仿真试验验证了本文算法的有效性,表明识别算法不受同步码型和数据量的约束,并且算法的抗误码性能较好、识别速度较快,因此具有一定的工程应用价值。 相似文献
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SAID E. EL-KHAMY 《International Journal of Electronics》2013,100(6):429-436
Combined Barker codes in which every bit of a Barker code is encoded by another Barker code are very useful as relatively long binary signals with good correlation properties. A code generator for the combined Barker code 13 × 4 is described in this paper. Measurements of the autocorrelation function and the power spectrum of this code are also presented and are compared with derived exact expressions. 相似文献
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PN序列因其优良的自相关性而被广泛应用.然而,PN序列因其自相关函数存在众多边峰、序列长度必须为2m-1(m∈Z)等而影响了其实用价值.本文提出了通过巴克码/正交巴克码/超巴克码与PN序列组合构造一种新的命名为低/零自相关(LZA)训练序列的设计方法.仿真证明:该法产生的LZA训练序列具有长度可以任意确定、除零时延处外该序列均有低/零自相关值、产生时所需储存容量和电路单元小、保密性高等优点.与众所周知的PN序列相比,LZA序列弥补了训练序列的不足,具有较高的理论意义和实用价值. 相似文献
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针对脉冲压缩体制短波信道探测对探测序列的自相关特性要求很高的问题,将周期自相关特性十分理想的Zadoff-Chu序列应用到短波信道探测中,设计了能充分利用其周期自相关特性的序列扩展方式,对Zadoff-Chu序列、m序列和巴克码的相关函数及相关函数的主旁瓣峰值比、品质因数、联合旁瓣电平率、峰均功率比四个参数进行了仿真和实测,对所得数据进行了讨论分析。分析表明:Zadoff-Chu序列比m序列和巴克码具有更好的自相关特性,其相关函数的主瓣峰值与旁瓣峰值之比、品质因数等四个参数比m序列和巴克码的相应参数更优越。 相似文献
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G. M. Strelkov A. V. Konovalova 《Journal of Communications Technology and Electronics》2010,55(7):721-732
A rectangular radio pulse formed on the basis of the Barker code and transmitted over a long-distance ionospheric path is
considered. The character of signal distortions and the rate of their increase are analyzed. The determining effect of the
initial duration and carrier frequency of the signal on its current characteristics is revealed. For the decameter wavelength
band, it is shown, that, when the parameters of the problem vary within a wide range, the autocorrelation function of a Barker
signal is deformed, its center maximum being preserved and substantially spread. 相似文献
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Binary phase codes for radar pulse compression giving compression ratios greater than 13 (the maximum-length Barker code) must generally be found by trial and error on a digital computer. Formulas are derived for the maximum number of codes of given length which have different autocorrelation functions, and it is shown how redundant codes can be recognised without evaluating the autocorrelation functions. 相似文献
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二值映射相关Barker码研究 总被引:3,自引:0,他引:3
给出了二相序列非周期二值映射相关函数的定义,在该定义的基础上定义了二值映射相关Barker码(简称二值加权Barker码),并指出经典的二相序列的非周期相关函数和Barker码是本文新定义的相关函数和Barker码的特例。新定义的Barker码比原意义的Barker码多5个码字,而且对原意义下的Barker码经加权处理后,可提高主副峰比(长为7的Barker码提高2.5dB,长为11的Barker码提高1.57dB),计算机搜索结果证明长度大于13、小于31的二值加权Barker码是不存在的。 相似文献
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On n-phase Barker sequences 总被引:1,自引:0,他引:1
Ning Chang Golomb S.W. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1994,40(4):1251-1253
An n-phase Barker sequence can be easily distinguished from the time-shifted versions of itself. This property is important for such applications as radar systems, synchronization systems, and spread-spectrum communications systems. The authors study some transformations on n-phase Barker sequences. Also, they give an efficient algorithm for finding sextic Barker sequences. Through an exhaustive computer search, numerical data for n-phase Barker sequences are given. Specifically, they extend the list of known n-phase Barker sequences to length L=19 相似文献
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Polyphase sequences are time-discrete complex sequences with constant magnitude and variable phase. In this letter polyphase sequences with aperiodic autocorrelation function (ACF) sidelobes of values less than or equal to 1 are presented. Such sequences are called Barker sequences. Binary Barker sequences with elements 1 or -1 are only known up to 13 elements. Now, with an iteration scheme, polyphase Barker sequences are found up to 25 elements, except for 20 elements.<> 相似文献
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Woo-Kyung Lee 《Communications Letters, IEEE》2006,10(5):387-389
Sequences with low autocorrelation levels are highly desirable in digital communication. Conventional sidelobe reduction techniques have suffered from performance degradations in range resolutions and signal-to-noise ratio (SNR) gains. In this paper we propose a way to synthesize amplitude weight correlators for polyphase codes. These weighted codes generate sidelobes that are lower than those found in Barker codes. The sidelobe level is kept uniformly flat over all time delays while the range resolution loss is prevented. Unlike the Barker codes, the proposed technique is not limited by the code length. The technique is easy to implement and incurs a minimal SNR loss. 相似文献