【作者】 马晓龙；

【导师】 陈桂芬；

【作者基本信息】 长春理工大学 ， 物理电子学， 2002， 硕士

【摘要】 本论文将介绍一种软件模拟硬件的方法来实现PCM-CDMA-BPSK中频信号的快捕、跟踪和解调。关于扩频信号的传统的研究是在理想的条件下，比如低码率、窄动态范围、窄频率变化范围等等。对高动态、高码率、低信噪比、大多普勒及变化的码长和码率的扩频信号的快捕是本文的难点。 在扩频信号的捕获过程中要求有较小的时延和较高的概率，本文介绍一种二维信号的捕获方法，这种方法结合伪PN码和载波频率的获取，捕获时延将大幅度降低，实际上，扩频信号的检测是接收系统的关键。本文介绍一种通过积累能量新方法来改善输入信号的信噪比从而改善检测性能。 接收机稳定可靠地跟踪被捕获信号保证成功解调是必要的，本文介绍一种改善的锁相环设计方法，这种方法采用自适应参数和变带宽跟踪技术来调整输入信号改善捕获和跟踪性能。捕获和跟踪的性能指标：伪随机信号码率1M～5M比特/秒，码长是255、511，接收灵敏度是-118dB，信号动态范围是70dB载波普勒是±75kHz，目标捕获在0.2秒内。更多还原

【Abstract】 In this thesis, a kind of software method is researched to realize the functions of fast acquisition , tracking and demodulation of PCM-CDMA-BPSK intermediate frequency signals.Conventional research on spread spectrum signals is in the case of ideal conditions, such as low code rate , narrow dynamic range , narrow frequency-changing range and so on. The specialities and difficulties of spread spectrum signals in this thesis are high dynamic. high code rate. low signal-to-nosie radio. wide Doppler range. varied code length, varied code rate, which have more difficulties.Little acquisition time and high acquisition probability are required during the capturing process of spread spectrum signals. In this thesis, a kind of 2-dimention signal acquisition method is presented which combines parallel PN code phase and carrier frequency acquisition, as a result the acquisition time is shortened greatly. Besides, according to the fact that the detection of spread spectrum signals is always the key point in the receiving system. A new method is presented in this thesis by which accumulates the energy to improve the signal-to-nosie ratio of input-signals, consequently improve the detection performance.It is necessary that the receiver tracks the acquired signals steadily and credibly to ensure the successful demodulation process. In this thesis, an improved tracking loop design method is presented which adopts self-adaptation parameters and varied bandwidth tracking technique to adapt to the input signals, and improves the acquisition and tracking performance.The performance targets of acquisition and tracking: the code rate of pseudorandom signals is 1M-5MHz, the code length is 255. 511, the receiving sensitivity is -118dBm,the dynamic range is 70dB. the Doppler of carrier is 75kHz,the time that 10 targets are captured within 0.2s.更多还原