摘要
扩频技术是一种无线通信技术，具有抗人为干扰和无意干扰、低截获概率、实现码分多址以及抗多径效应等有用的性能特点，因此，这种技术广泛应用于军事通信领域。市场上现有的扩频发射和接收机主要由模拟器件、常规IC、匹配滤波器和一般用途的信号处理器构成，这种发射接收机具有设备量大，受外界影响大，性能不稳定等缺点。本论文根据信息产业部电子十所的国防某工程预研项目要求，以全数字式的直接序列扩频收发专用芯片STEL—2000A为核心，辅以若干外围器件，设计了一个数字扩频收发系统，完成了该扩频收发系统中频、基带部分的软硬件设计、实现及调试，达到了设计要求。该系统设计灵活方便，外围电路简单，设备量小，且性能稳定可靠。
本论文的主要工作有：
1)系统地讨论了基于数字匹配滤波器的PSK直序解扩方案及影响数字匹配滤波器捕获跟踪性能的因素。
2)讨论了基于STEL—2000A的扩频收发系统中，中频选择问题。
3)详细地讨论了全数字式直序扩频收发芯片STEL-2000A的主要性能，根据课题要求，完成了基于全数字式直序扩频收发专用芯片STEL-2000A的扩频收发系统的软硬件设计和调试。
It is well known that spread-spectrum (SS) communication techniques is a kind of wireless communication one, which offer several desirable performance characteristics such as immunity to jamming and interference, low probability of interception, code division multiple access, and multi-path protection. Because of these features, spread-spectrum techniques have been widely used in military applications. Nowadays, commercially available spread-spectrum transceivers primarily use discrete analog technology, which has some shortcomings such as large quantity of devices, affected easily, and less reliable performance. In this paper, a spread-spectrum transceiver system that employed a single-chip all-digital PSK direct sequence spread-spectrum IF transceiver ASIC?STEL-2000A is presented. This system consists of STEL-2000A, and some simple peripheral circuits, which is setup simply and dexterously, more reliable, and need less devices. Baseband and intermediate frequency (IF) processing including its software and hardware circuit design, implements and debugging are finished in this paper. Experiments prove that this system can function correctly.
The main work of this paper is summarized as follows:
1) Discuss systematically the principle of a PSK direct sequence despread-spectrum scheme based on the digital matched filter (DMF). Also, performance analysis of DMF for PN code acquisition and tracking is given.
2) Discuss the choice of the proper IF in the STEL-2000ADS ?SS transceiver.
3) Introduce thoroughly the performance, characteristics of STEL-2000A and setup method of its control registers in the real communication system. Finish software and hardware design, implement and debugging of a spread-spectrum transceiver system by the requirement of the project.
引文
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