直扩通信中扩频序列的同步问题研究
发布时间：2019-03-30 13:08
【摘要】：由于扩频通信具有保密性好,抗干扰性强的特点,因此在各个领域内倍受关注,至今,扩频通信技术已经被非常广泛的运用在军事、民事、和商业领域。扩频通信系统虽然优点众多,运用广泛,但是相比于普通的通信系统,扩频通信系统的硬件结构和软件算法更为复杂,这限制了扩频通信技术的发展。在扩频通信系统中,只有发送端用于扩频的伪随机序列与在接收端用于解扩频的伪随机序列相同,且相位也完全相同的条件下才能正确的解扩频得到发送信息序列。目前如何保证发送端伪随机序列与接收端的伪随机序列的同步问题是扩频通信系统中最为关键的技术,也是本文的研究出发点。本文从扩频码的特点出发,首先介绍了直接扩频通信信号的模型,接着介绍了在直扩通信中常用的伪随机码类型,最后着重介绍了在直扩通信中长、短周期扩频码的捕获算法。在短周期伪随机码的捕获方法中,由于短周期码速率慢,数据量少,可以进行直接捕获。本文推导了采用匹配滤波器和快速傅里叶变换算法代替滑动相关算法的原理,两种算法在不同程度上提高了捕获速度,但是二者对于多普勒频率过于敏感,且算法不能直接移植到超长周期伪随机码的捕获上,有一定的局限性。在超长周期或无周期伪随机码的相位捕获方法中,着重介绍了基于分组折叠相加、分组均值,以及二者综合的三种算法。基于分组折叠相加的算法是把伪随机码折叠并相加,使其增大一次相关的搜捕范围。分组均值算法是采用分多个组,然后再组内多个点求平均值转化为一个点,这样在相关点数一定的条件下,增大了搜捕范围。综合算法则是综合了二者的优势,使捕获速度进一步加快。但由于综合算法的多普勒频率补偿有误差,不能完全去掉多普勒对相关峰值的影响且在去模糊阶段有冗余,本文提出了一种新的算法,用信号序列傅里叶变换后循环移位代替多普勒补偿数值,并在去模糊阶段采用基于二分的查找算法,通过matlab仿真分析,新算法在一定程度上提高了伪码相位的捕获性能。
[Abstract]:Spread spectrum communication has been widely used in military, civil and commercial fields since it has the characteristics of good security and strong anti-interference, so it has been paid more and more attention in various fields, so far, spread spectrum communication technology has been widely used in military, civil and commercial fields. Although the spread spectrum communication system has many advantages and is widely used, the hardware structure and software algorithm of the spread spectrum communication system are more complex than the ordinary communication system, which limits the development of the spread spectrum communication technology. In the spread spectrum communication system, only when the pseudorandom sequence used by the transmitter is the same as the pseudorandom sequence used for despreading the spectrum at the receiving end, and the phase is exactly the same, can the transmission information sequence be obtained correctly. At present, how to ensure the synchronization between the pseudo-random sequence at the transmitter and the pseudo-random sequence at the receiving end is the most important technology in the spread spectrum communication system, and it is also the starting point of this paper. Starting from the characteristics of spread spectrum code, this paper first introduces the model of direct spread spectrum communication signal, then introduces the type of pseudo random code commonly used in direct spread spectrum communication, and finally introduces the acquisition algorithm of long and short period spread spectrum code in direct spread spectrum communication. In the acquisition method of short-period pseudorandom code, it can be directly captured because of the slow rate of short-period code and the small amount of data. In this paper, the principle of using matched filter and Fast Fourier transform (FFT) instead of sliding correlation algorithm is deduced. The two algorithms improve the acquisition speed to some extent, but they are too sensitive to Doppler frequency. Moreover, the algorithm can not be directly transplanted to the acquisition of ultra-long period pseudorandom codes, which has some limitations. In the phase acquisition method of extra-long period or non-periodic pseudorandom codes, three kinds of algorithms based on the addition of packet folding, the mean of packets and the combination of them are introduced emphatically. The algorithm based on the addition of packet folding is to fold and add pseudo random code to enlarge the range of one-time correlation search. The grouping mean algorithm is divided into multiple groups, then the average value of multiple points in the group is transformed into a point, so that under the condition of certain correlation points, the search range is enlarged. Synthesis algorithm is to synthesize the advantages of the two, so that the capture speed is further accelerated. However, due to the error in the Doppler frequency compensation of the synthetic algorithm, the influence of Doppler on the correlation peak can not be completely removed and there is redundancy in the deblurring phase. A new algorithm is proposed in this paper. The Doppler compensation value is replaced by the cyclic shift after Fourier transform of signal sequence, and the binary-based search algorithm is adopted in the phase of de-ambiguity. The new algorithm improves the acquisition performance of pseudo-code phase to a certain extent by matlab simulation analysis.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN914.42
本文编号：2450107
[Abstract]:Spread spectrum communication has been widely used in military, civil and commercial fields since it has the characteristics of good security and strong anti-interference, so it has been paid more and more attention in various fields, so far, spread spectrum communication technology has been widely used in military, civil and commercial fields. Although the spread spectrum communication system has many advantages and is widely used, the hardware structure and software algorithm of the spread spectrum communication system are more complex than the ordinary communication system, which limits the development of the spread spectrum communication technology. In the spread spectrum communication system, only when the pseudorandom sequence used by the transmitter is the same as the pseudorandom sequence used for despreading the spectrum at the receiving end, and the phase is exactly the same, can the transmission information sequence be obtained correctly. At present, how to ensure the synchronization between the pseudo-random sequence at the transmitter and the pseudo-random sequence at the receiving end is the most important technology in the spread spectrum communication system, and it is also the starting point of this paper. Starting from the characteristics of spread spectrum code, this paper first introduces the model of direct spread spectrum communication signal, then introduces the type of pseudo random code commonly used in direct spread spectrum communication, and finally introduces the acquisition algorithm of long and short period spread spectrum code in direct spread spectrum communication. In the acquisition method of short-period pseudorandom code, it can be directly captured because of the slow rate of short-period code and the small amount of data. In this paper, the principle of using matched filter and Fast Fourier transform (FFT) instead of sliding correlation algorithm is deduced. The two algorithms improve the acquisition speed to some extent, but they are too sensitive to Doppler frequency. Moreover, the algorithm can not be directly transplanted to the acquisition of ultra-long period pseudorandom codes, which has some limitations. In the phase acquisition method of extra-long period or non-periodic pseudorandom codes, three kinds of algorithms based on the addition of packet folding, the mean of packets and the combination of them are introduced emphatically. The algorithm based on the addition of packet folding is to fold and add pseudo random code to enlarge the range of one-time correlation search. The grouping mean algorithm is divided into multiple groups, then the average value of multiple points in the group is transformed into a point, so that under the condition of certain correlation points, the search range is enlarged. Synthesis algorithm is to synthesize the advantages of the two, so that the capture speed is further accelerated. However, due to the error in the Doppler frequency compensation of the synthetic algorithm, the influence of Doppler on the correlation peak can not be completely removed and there is redundancy in the deblurring phase. A new algorithm is proposed in this paper. The Doppler compensation value is replaced by the cyclic shift after Fourier transform of signal sequence, and the binary-based search algorithm is adopted in the phase of de-ambiguity. The new algorithm improves the acquisition performance of pseudo-code phase to a certain extent by matlab simulation analysis.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN914.42
【参考文献】
相关期刊论文 前5条
1 张博;杨春;解楠;罗晓莉;;FFT快速捕获算法在GPS C/A码与P(Y)码中的应用[J];电讯技术;2008年12期
2 国世超;陈安乐;韩方剑;;基于部分匹配滤波的伪码捕获方法研究[J];电子信息对抗技术;2010年02期
3 李一兵;殷潜;毕晓艳;;直扩系统滑动相关捕获方法性能研究[J];黑龙江大学自然科学学报;2005年05期
4 李立言;钟杰;赵民建;;一种低复杂度GNSS信号快速捕获算法[J];哈尔滨工业大学学报;2013年03期
5 肖模艳;何志彪;;基于重叠的P码频域直接捕获法研究[J];湖北第二师范学院学报;2013年02期
，本文编号：2450107
本文链接：https://www.wllwen.com/kejilunwen/wltx/2450107.html
