摘要
直接序列扩频体制广泛应用于卫星通信系统、导航定位系统、测距系统和雷达系统中，相关旁瓣对信号的检测性能有影响，可造成系统性能损耗。
本文以国防重点型号装备研制项目双星定位系统的出入站信道容量分析和快捕信号设计为研究背景，研究了相关旁瓣的特性，并对自相关旁瓣和互相关旁瓣引起的性能损耗进行了分析。
论文的主要工作包括三部分：
第一部分分析了几种情况下的相关旁瓣特性。为简化运算，便于分析，提出了等效旁瓣的概念。
第二部分分析了未知时延时相干和非相干接收情况下自相关旁瓣对检测性能的影响，给出了常见的周期m序列、小Kasami序列和截短序列的分析实例，并与确知时延时的性能进行了比较。分析了上述两种接收方式下的旁瓣损耗，为信道容量提供了必要的数据。最后分析了非相干接收情况下，存在多普勒频移时相关旁瓣的特点，可研究它对检测性能的影响及对系统造成的损耗。
第三部分介绍了当前多址干扰的研究现状，简要分析了互相关旁瓣与多址干扰的关系。根据实际工程的需要，建立了无完善的功率控制条件下相干与非相干两种接收方式时随机多址扩频通信模型，指出多址干扰是(信号到接收机的)距离、伪码互相关旁瓣、(各用户载波相对于接收机的)相位的连续随机变量函数。
本文的研究成果将在“十五”国防预研“卫星导航定位系统长码直捕”项目中作为编码优选的考虑因素之一。
The direct spread spectrum system is widely applied into multiple access communication, satellite-based navigation-position systems and radar systems. The correlation side-lobes have effect on detection performance of signal and make side-lobe loss as a result.
This article is based on the two-star-position systems, the key project of nation defense. The character of correlation side-lobes is mainly discussed and the difference effect on system between the auto-correlation and cross-correlation is given.
In the first part, the properties of correlation side-lobes are discussed. The equivalent side-lobes are given so as to simplify the calculation and analysis in the end of this part.
In the second part, the side-lobes effect on detection performance is analyzed under the condition of coherent and un-coherent receiver. The analysis is based on m sequence, small Kasami sequence and truncation code and compared with the definite time delay. The side-lobes loss given is helpful to the analysis of channel capacity. In the end, this article considered the side-lobes with Doppler frequency as definite side-lobes and has studied the effect on detection performance and the side-lobes loss.
In the third part, the status of the multiple access interference (MAI) and the relationship between the cross-correlation and MAI are introduced. In order to meet the need of the practical project, without the perfect power control, this article set up the model for multiple access communication under the condition of coherent and un-coherent receiver and considered the MAI which is determined by range, cross-correlation and phase as the correlation side-lobes.
The result of this article is to be used to the PN code choice in the project of long pseudo-noise code capture in the satellite-based navigation-position systems.
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