發(fā)布時間：2018-09-14 06:45

【摘要】：無線通信發(fā)展至今,已經廣泛應用于各個領域,但空間電磁環(huán)境復雜多變,通信系統的可靠性依然受到空間干擾的威脅。基于擴頻技術的直接序列擴頻(DSSS)系統的抗干擾性強、保密性高、截獲概率低,成為現今眾多通信系統中最常用的通信系統并應用到各個領域。雖然DSSS系統可以在具有一定干擾存在的空間環(huán)境中正常工作,但當干擾信號的強度超過系統干擾容限時,系統通信的可靠性將無法得到保證,通信抗干擾技術是保障通信可靠性的必要途徑,而干擾檢測技術是通信抗干擾技術的基礎也是關鍵技術,因此,針對DSSS系統干擾檢測技術的研究具有重要的現實意義。首先,本文介紹了DSSS系統和干擾檢測技術的基本原理、干擾門限的選取方法和虛警概率的計算,為DSSS系統干擾檢測技術的研究奠定了理論基礎。其次,對DSSS系統中常見的干擾信號進行了建模、分析,并給出了信號的數學表達式。詳細研究了干擾檢測技術中常用的頻域干擾檢測算法:一般干擾檢測算法、連續(xù)均值去除算法(CME)、前向連續(xù)均值去除算法(FCME)、雙門限算法。最終改進了FCME算法,運用MATLAB仿真了窗函數對算法干擾檢測性能的影響和不同干擾檢測算法之間檢測性能的差異。通過仿真、分析、比較可知,在同一檢測概率下,使用漢明窗(Hamming)的改進FCME算法比其他幾種算法的整體檢測性能更好。最后,利用FPGA對改進FCME算法進行硬件實現,設計出干擾檢測通信系統,并在靜默周期和非靜默周期下,分別測試了系統對單音干擾、多音干擾以及窄帶干擾的檢測性能。測試結果表明,改進FCME算法的實際檢測性能與運用軟件仿真時的檢測性能接近,信號的信噪比不同,系統對干擾信號的檢測性能也不一樣。在靜默周期下,系統能夠對干噪比大于-30d B的單音干擾信號、干噪比大于-26d B的多音干擾信號以及干噪比大于-4d B的窄帶干擾信號正確檢測出頻點的位置。在非靜默周期下,信噪比為-15d B時,系統能夠對干噪比大于-29d B的單音信號、干噪比大于-24d B的多音信號以及干噪比大于-3d B的窄帶信號正確檢測出頻點的位置。信噪比為0d B時,系統能夠對干噪比大于-23d B的單音信號、干噪比大于-18d B的多音信號以及干噪比大于2d B的窄帶信號正確檢測出頻點的位置。該干擾檢測通信系統對常見類型的干擾信號表現出很好的檢測性能。
[Abstract]:Since the development of wireless communication, it has been widely used in various fields, but the electromagnetic environment in space is complex and changeable, and the reliability of communication system is still threatened by space interference. The direct sequence spread spectrum (DSSS) system based on spread spectrum technology has strong anti-interference, high security and low probability of interception. It has become the most commonly used communication system in many communication systems and has been applied to various fields. Although the DSSS system can work normally in the space environment where the interference exists, the reliability of the system communication will not be guaranteed when the intensity of the interference signal exceeds the interference tolerance limit of the system. The communication anti-jamming technology is the necessary way to guarantee the communication reliability, and the interference detection technology is the foundation and the key technology of the communication anti-jamming technology. Therefore, it is of great practical significance to study the interference detection technology of the DSSS system. Firstly, this paper introduces the basic principle of DSSS system and interference detection technology, the selection method of interference threshold and the calculation of false alarm probability, which lays a theoretical foundation for the study of interference detection technology in DSSS system. Secondly, the common interference signals in DSSS system are modeled, analyzed, and the mathematical expressions of the signals are given. The frequency-domain interference detection algorithms commonly used in interference detection are studied in detail: general interference detection algorithm, continuous mean removal algorithm, (CME), forward continuous mean removal algorithm, (FCME), double threshold algorithm. Finally, the FCME algorithm is improved, and the influence of window function on the performance of interference detection and the difference between different algorithms are simulated by MATLAB. Through simulation and analysis, we can see that under the same detection probability, the improved FCME algorithm using hamming window (Hamming) has better overall detection performance than other algorithms. Finally, the improved FCME algorithm is implemented by using FPGA, and the interference detection communication system is designed, and the detection performance of monophonic interference, multi-tone interference and narrowband interference is tested under silence period and non-silence period, respectively. The test results show that the actual detection performance of the improved FCME algorithm is similar to that of the software simulation. The signal-to-noise ratio of the signal to noise is different, and the detection performance of the interference signal is not the same. In the silent period, the system can correctly detect the position of the frequency points for the single tone interference signal with a dry noise ratio greater than -30 dB, the multi-tone interference signal with a dry noise ratio greater than -26 dB and the narrow band interference signal with a dry noise ratio greater than -4 dB. When the signal-to-noise ratio (SNR) is -15dB, the system can correctly detect the position of the frequency points for the single-tone signal with a signal-to-noise ratio greater than -29dB, the multi-tone signal with a dry-noise ratio greater than -24dB and the narrow-band signal with a signal-to-noise ratio greater than -3dB. When the signal-to-noise ratio (SNR) is 0 dB, the system can correctly detect the position of the frequency point for the single tone signal with a signal-to-noise ratio greater than -23 dB, the multi-tone signal with a dry-noise ratio greater than -18 dB and the narrow band signal with a signal-to-noise ratio of more than 2 dB. The interference detection communication system has good detection performance for common types of interference signals.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN972

【相似文獻】

相關期刊論文 前10條

1 肖治宇;呂明;唐斌;;DSSS/QPSK信號盲檢測方法仿真[J];電子科技;2007年09期

2 董占奇;趙迪;;一種快速DSSS/QPSK信號檢測方法[J];河南師范大學學報(自然科學版);2011年03期

3 金光浪;宋茂忠;;基于數字混沌序列的DSSS通信系統仿真[J];現代電子技術;2007年06期

4 金光浪;宋茂忠;;數字混沌序列在DSSS通信中的誤碼率仿真[J];信息安全與通信保密;2007年06期

5 陳源;汪小潔;袁嗣杰;;一種提高DSSS信號載波頻率估計精度的算法[J];裝備指揮技術學院學報;2008年03期

6 馬麗華;楊慧中;;一種低信噪比下DSSS的載頻估計方法[J];計算機工程與應用;2010年05期

7 張穎光,保錚,張林讓,廖桂生;DSSS通信系統中干擾環(huán)境下碼捕獲和陣列權值聯合捕獲[J];電子學報;2004年12期

8 ;Parameter estimation of DSSS signals in non-cooperative communication system[J];Journal of Systems Engineering and Electronics;2007年01期

9 夏彩杰;安建平;王愛華;;New Technique for Estimating and Suppressing Narrowband Interference in DSSS Systems[J];Journal of Beijing Institute of Technology;2007年03期

10 ;DSSS無線數字同聲傳譯[J];電聲技術;2007年10期

相關會議論文 前6條

1 蔡艷軍;李軒;宋衛(wèi)星;;利用DSSS技術提高衛(wèi)星通信系統抗干擾性能[A];中國通信學會第五屆學術年會論文集[C];2008年

2 王喬邦;郭偉;;一種有效的DSSS信號的PN序列的盲同步方法[A];2006中國西部青年通信學術會議論文集[C];2006年

3 龔e，

本文編號：2241856