基于m序列的扩频通信系统的仿真设计毕业设计论文(编辑修改稿)

基于m序列的扩频通信系统的仿真设计毕业设计论文(编辑修改稿)内容摘要：

频 主要用意是避免 “ 不好 ” 的频道使用仅在 “ 良好 ” 的频率 —— 或许那些 “ 不良 ” 的频道遇到 频率选择性衰落 ， 或者一些第三方试图对这些波段沟通，或者那些波段正在被积极地干扰。 因此， 自适应跳频扩频 应 从 检测好 /坏 信道 的机制 中得到补充。 但是，如果无线电频率干扰本身就是动态的，那么“坏信道清除”的策略在自适应跳频应用可能无法工作。 例如，如果有几个同位跳频网络（如蓝牙 技术的微微网 ）， 8 那么他们是相互干扰且自适应跳频的策略未能避免这种干扰。 在这种情况下，有需要使用动态适应的频率跳变模式的策略。 这种情况往往发生在无节制的情况下使用频谱。 此外，动态无线电频率的干扰，预计发生涉及感知无线电的方案中， 该方案中会出现网络和设备应展示变频操作。 线性调频扩频 可以被视为一种跳频，只需通过可用频率以连续顺序扫描。 三、 线性调频扩频 一个线性调频时间域中的 上线性调频信号 线性调频扩频 (CSS)是一种 扩频 技术使用宽带线性调频脉冲对信息进行编码。 一个线性调是在一定时间正弦信号频率的增加或减少。 上 面是一个 线性调频信号 的一个示例 可以看到随着时间的推移频率线性增加。 概 述 如同其他扩频方法，线性调频频谱使用其全部分配到的带宽广播信号，使信道噪声强劲。 此外，由于线性调频利用了 频谱的宽带，线性调频扩频也能够抵抗多径衰落，即使在非常低的功率下运行。 然而，与直接序列扩频（ DSSS）或频率跳频（ FHSS），由于它不添加任何伪随机的信号分量，以帮助区分的信道噪声它扩频，而不是依靠线性调频脉冲的线性性质。 此外，调频扩频的抗多普勒效应，这是在移动无线应用的典型。 使 用 线性调频 扩频最初设计 是 为与测距精度及低速率无线网络在 GHz 频带中的 超宽带 竞争。 但是，自 美国电气和电子工程师 协会 （也称为 IEEE ) 的版本， 它不再是正积极考虑为在标准化领域测距的精度规程。 目前， Nanotron 科技，生产实时定位装置，并获得线性调频扩频主要力量后加入到电机及电子学工程师联合会 标准，是唯一使用线性调频扩频的无线设备卖方。 特别是，他们的主要 9 产品， NanoLOC 的 TRX 收发器，使用在线性调频扩频和作为一个实时的网络设备销售位置和电子标签能力。 有些地方这种技术可能是有作用的是医疗应用，物流（即容器需要被跟踪），以及政府 /安全应用。 Nanotron 甚至测试 TRX 收发器用于在钢厂工业监测 和控制 ， 它 能 存 在于导致的计算机和 显示 器与它连接失败的热量中。 调频扩频非常适合需要低功耗的应用程序和需要的带宽数量相对较少（ 1 兆比特 /秒或更少）的情况下。 特别是在 指定 线性调频扩频 作为一种低速率无线技术 在 个人局域网 (LR— WPAN）中使用。 但是， 尽管 标准指定 个人区域网络 包含 10米的或较少的区域 ， IEEE 指定线性调频扩频在物理层使用时延长范围和设备在高速移动作为是您的网络运行的一部分。 Nanotron 的线性调频扩频的执行工作，实际上是看到在 570 米范围内的设备之间。 此外， Nanotron为该项目的执行能够工作在数据传输速率可高达 2 Mbit/s 比 任务指定的速率要高。 最后， IEEE 标准的物理层实际上混合 线性调频扩频 编码技术与差分相移键控调制 (DPSK)以达到更好的数据传输速率。 线性调频扩频也可用于军事应用前景，因为它是非常困难的探测和拦截时，在低功耗工作。 四、 时间跳频 时间跳频 通信中 ， 传播中的承运人打开和关闭的伪代码序列的频谱技术。 这里就不再赘述。 10 Spread Spectrum Techniques By Wikipedia Abstract: Spreadspectrum techniques are methods by which a signal (. an electrical, electromagic, or acoustic signal ) generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure munications, increasing resistance to natural interference and jamming, to prevent detection, and to limit power flux density (. in satellite downlinks). History Frequency hopping: The concept of frequency hopping was first alluded to in the 1903 . Patent 723,188 and . Patent 725,605 filed by Nikola Tesla in July 1900. Tesla came up with the idea after demonstrating the world39。 s first radiocontrolled submersible boat in 1898, when it became apparent the wireless signals controlling the boat needed to be secure from being disturbed, intercepted, or interfered with in any way. His patents covered two fundamentally different techniques for achieving immunity to interference, both of which functioned by altering the carrier frequency or other exclusive characteristic. The first had a transmitter that worked simultaneously at two or more separate frequencies and a receiver in which each of the individual transmitted frequencies had to be tuned in, in order for the control circuitry to respond. The second technique used a variablefrequency transmitter controlled by an encoding wheel that altered the transmitted frequency in a predetermined manner. These patents describe the basic principles of frequency hopping and frequencydivision multiplexing, and also the electronic ANDgate logic circuit. Frequency hopping is also mentioned in radio pioneer Johannes Zenneck39。 s book Wireless Telegraphy (German, 1908, English translation McGraw Hill, 1915), although Zenneck himself states that Telefunken had already tried it several years earlier. Zenneck39。 s book was a leading text of the time, and it is likely that many later engineers were aware of it. A Polish engineer, Leonard Danilewicz, came up with the idea in other patents were taken out in the 1930s, including one by Willem Broertjes (Germany 1929, . Patent 1,869,695, 1932). During World War II, the US Army Signal Corps was inventing a munication system called SIGSALY for munication between Roosevelt and Churchill, which incorporated spread spectrum, but due to its top secret nature, SIGSALY39。 s existence did not bee known until the 1980s. The most celebrated invention of frequency hopping was that of actress Hedy Lamarr and poser Gee Antheil, who in 1942 received . Patent 2,292,387 for their Secret 11 Communications System. Lamarr had learned about the problem at defense meetings she had attended with her former husband Friedrich Mandl, who was an Austrian arms manufacturer. The AntheilLamarr version of frequency hopping used a pianoroll to change among 88 frequencies, and was intended to make radioguided torpedoes harder for enemies to detect or to jam. The patent came to light during patent searches in the 1950s when ITT Corporation and other private firms began to develop Code Division Multiple Access (CDMA), a civilian form of spread spectrum, though the Lamarr patent had no direct impact on subsequent technology. It was in fact ongoing military research at MIT Lincoln Laboratory, Magnavox Government amp。 Industrial Electronics Corporation, ITT and Sylvania Electronic Systems that led to early spreadspectrum technology in the 1950s. Parallel research on radar systems and a technologically similar concept called phase coding also had an impact on spreadspectrum development. Commercial use The 1976 publication of Spread Spectrum Systems by Robert Dixon, ISBN 0471216291, was a significant milestone in the mercialization of this technology. Previous publications were either classified military reports or academic papers on narrow subtopics. Dixon39。 s book was the first prehensive unclassified review of the technology and set the stage for increasing research into mercial applications. I。