GPS信號P碼發(fā)生器設(shè)計

論文編號:TX418  論文字數(shù):23721,頁數(shù):57

摘 要

    GPS系統(tǒng)采用偽碼測距的原理，其采用的偽隨機序列之一的P碼具有很強的抗干擾和保密性能，一直以來為軍方所用。GPS系統(tǒng)中P碼的捕獲通常是先捕獲到C/A碼，然后利用C/A碼調(diào)制的導(dǎo)航電文中的HOW所提供的P碼信息對P碼進行捕獲。然而，C/A碼的碼長短，碼速率低易受干擾，因此很難通過C/A碼來捕獲到P碼，直接捕獲P碼一直以來備受關(guān)注，產(chǎn)生P碼并對其特性進行分析對進一步研究碼的捕獲有重要意義。
    這篇論文在MAX+PLUSⅡ環(huán)境下，根據(jù)ICD-200設(shè)計了P碼發(fā)生器，并進行了仿真，對GPS星期的開始和結(jié)束進行了仿真驗證。設(shè)計的P碼發(fā)生器在開始和結(jié)束產(chǎn)生的碼序列是正確的。用P碼對的導(dǎo)航電文進行了直接序列擴頻。最后利用MATLAB對部分P碼進行了相關(guān)性驗證。

關(guān)鍵詞：GPS信號；P碼；MAX+PLUSⅡ；仿真；相關(guān)

Abstract
 
 The GPS system uses the pseudo-code to obtain the range. One of the pseudorandom noise codes used is p-code, which has very strong anti-jamming and secrecy. It has been widely used in the military. Traditionally, the GPS receiver locks onto the C/A code to extract the navigation data message. Then, starting from the HOW of the navigation data, acquisition is transferred to the P-code acquisition. However, because of short period and low chip rate, C/A code is easily disturbed. As a result it is very hard to use the C/A code to implement the p-code acquisition. The direct acquisition of p-code has been paid attention to generate p-code and analysis its characteristic. This will have an important significance for the deep research of p-code acquisition.
 The overall objective of this dissertation is to implement the design of p-code generator and simulator using the MAX+PLUS. As the result shows, the GPS week starting and ending codes generated by the designed generator are right. Then using the p-code implement the direct sequence spread spectrum to the navigation data. Finally, using the matlab verifies the correlation of part p-code.
 
 Key words: GPS signal; P code; MAX+PLUSⅡ; simulate; correlation
 
  
 目錄

1  緒論 1
1.1  GPS的發(fā)展 1
1.2  GPS的組成 2
1.3  GPS的特點 4
1.4  GPS的應(yīng)用 5
1.5  課題介紹 5
2 GPS的基本原理 6
2.1  地心地球固連(ECEF)坐標系 6
2.2  GPS偽碼測距原理 6
2.2.1  偽距計算 7
2.2.2   用戶位置計算 8
2.3  GPS信號調(diào)制格式 8
2.3.1  GPS的傳輸信號分類 8
2.3.2  GPS衛(wèi)星信號的組成 9
2.3.3  GPS的導(dǎo)航電文 10
2.4  碼分多址 12
3 MAX+PLUSⅡ軟件開發(fā)系統(tǒng)簡介 13
3.1  設(shè)計輸入 15
3.2  設(shè)計項目的編譯 19
3.3  設(shè)計校驗 25
4   GPS信號P碼的仿真 29
4.1  偽隨機碼的產(chǎn)生及特性分析 29
4.2  P碼的產(chǎn)生 31
4.3  P碼發(fā)生器仿真結(jié)果分析 33
4.3.1  P碼發(fā)生器初始狀態(tài)的確定 33
4.3.2  P碼發(fā)生器的仿真 34
4.4  利用P碼進行擴頻 42
4.5  P碼的相關(guān)性驗證 43
致謝 45
參考文獻 46
附錄A  英文原文 47
附錄B  英文翻譯 52