共查询到18条相似文献,搜索用时 109 毫秒
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伽利略系统采用了长扩频码序列以提高扩频码的互相关性能,但同时大大增加了搜索区间,采用单驻留搜索策略的系统平均捕获时间将因此增加数倍.使用双驻留机制对系统性能进行优化,在系统虚警概率和发现概率保持不变的前提下,将典型信噪比下的平均捕获时间减小20%~90%.系统仿真证明了算法的有效性. 相似文献
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在北斗或GPS定位系统中,噪声环境下的快速捕获是信号处理的重要环节。提出了一种基于PMF-FFT改进算法的信号同步捕获方法,可以在硬件资源有限的情况下提高多普勒频偏估计精度,并在不增加FFT点数的条件下减少相关增益存在的损失,该改进算法综合考虑了捕获时间和硬件资源的消耗占比,优化了算法结构。对仿真结果做了分析,结果表明能够有效增加捕获概率,减少捕获时间。 相似文献
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图像采集系统中色彩复原模块的FPGA实现 总被引:1,自引:0,他引:1
图像的色彩复原是彩色图像采集系统的关键技术,决定了采集图像的质量.针对目前CMOS图像传感器广泛使用的Bayer格式图像,介绍了双线性插值法、梯度检测插值法和相关性插值法三种色彩复原算法:然后建立了基于Altera公司Cydone Ⅱ系列FPGA芯片的图像采集系统.并采用Verilog硬件描述语言在FPGA上实现了色彩复原算法.实验结果表明,该FPGA利用其丰富的内部硬件资源和并行处理的优势,能实时准确地完成色彩复原工作,同时,相关性插值法获得了最高峰值信噪比.恢复的彩色图像边缘清晰平滑. 相似文献
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Long PN-code acquisition is a difficult and time-consuming task due to long code period.To accelerate acquisition,folding methods like XFAST are widely used.In highdynamic environment however,the application of those methods are largely restricted due to nonnegligible residual frequency.This paper proposes a new dual-channel method for fast acquisition of long PN-code.In the proposed method,both non-overlapping local PNcode blocks are employed to correlate with input sample block;the detection process is eased through finding the maximum value among correlation results and verification is made with all the full and partial peaks taken into account.False alarm probabilities from analysis of the verification process are derived.Both theoretical and Monte Carlo simulations reveal that,with respect to acquisition probability and mean acquisition time under the same false alarm rate,dual-channel method has advantage over zero-padding and XFAST based folding methods under certain false alarm probabilities. 相似文献
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本文论证了固定帧长度相关法是二进对称信道(BSC)的最佳帧同步算法。并用Poisson分布和Markov链导出了一次通过帧同步捕获概率,锁定概率以及进入锁定的平均时间,还给出了计算机模拟结果。与传统的门限法比较,本文给出的算法性能好,实现容易,有很大的应用价值。 相似文献
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隋厚棠 《电子科学学刊(英文版)》1992,9(3):200-208
The fixed frame length maximum correlation method which is the optimum methodover the binary symmetric channel has been proved.With Poisson distribution,the frame syncacquisition probability is obtained and followed by computer simulation.By Markov modelingtechniques,the probability and the mean time into lock mode are given.Finally,it is shown thatthe optimum frame sync method is far superior to conventional,and it is very useful in practice. 相似文献
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二维搜索捕获算法需要较长的捕获时间,采用基于分段并行相关的捕获方法,能够显著提高接收机的捕获速度。首先介绍了算法的原理,其次详细论述了分段并行相关器的结构。 在此基础上对相干积分时间、非相干积分次数以及捕获门限进行了详细的数学分析和计算机仿真。 最后,比较了选取不同相干积分时间和非相干积分次数条件下,算法的捕获性能。 相似文献
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Kim J.H. Sarin S.V. Yasunaga M. Oh H. 《Vehicular Technology, IEEE Transactions on》2001,50(1):278-286
We are proposing a new noncoherent pseudonoise code acquisition method for code-division multiple-access (CDMA) mobile communication systems. The proposed method employs two digital matched filters, and the code acquisition is based on a double dwell process. Through serial cascading of the dual-matched filters, the proposed code acquisition method does not lose the track of the incoming sequence even after returning from the false alarm state. This unique feature imparts on our design much desired stability. Moreover, the use of two matched filters increases the acquisition speed, which is of prime importance. One important issue in CDMA acquisition is how to determine the threshold values for optimal performance, the measure of optimality being the minimum mean acquisition time. In our performance analysis, we have derived the probability of detection and false alarm as a function of threshold values, then determine the threshold values that achieve the minimum mean acquisition time. Our performance analysis shows that the mean acquisition time is 35 ms at -15 dB input chip signal-to-noise ratio, much faster than the conventional active correlation technique 相似文献