【摘要】：最小頻移鍵控(MSK)調(diào)制結(jié)合擴頻通信體制,具有MSK信號的優(yōu)點和擴頻通信技術(shù)截獲概率低、保密性好、抗干擾能力強的特點,在戰(zhàn)術(shù)數(shù)據(jù)鏈、導(dǎo)彈制導(dǎo)指令數(shù)據(jù)傳輸、民用航空地空數(shù)據(jù)鏈、衛(wèi)星通信等領(lǐng)域得到了廣泛應(yīng)用。因此,開展直擴MSK調(diào)制解調(diào)技術(shù)研究具有重要的理論意義和應(yīng)用價值。本文研究了偽隨機序列特性,選擇擁有良好自相關(guān)和互相關(guān)特性的Gold碼作為擴頻碼。提出串行直擴MSK調(diào)制方式,推導(dǎo)直擴MSK信號的線性表達(dá)式,設(shè)計了直擴MSK調(diào)制及解擴解調(diào)實現(xiàn)方法,通過仿真分析驗證直擴MSK調(diào)制及解擴解調(diào)方案設(shè)計的可行性及其性能。詳細(xì)研究并分析了高動態(tài)下直擴MSK信號的捕獲和跟蹤技術(shù)。對基于匹配濾波器的常規(guī)碼捕獲方案進行改進,通過兩級碼捕獲平衡捕獲時間與硬件復(fù)雜度,采用雙差分相干碼捕獲法優(yōu)化捕獲性能。針對高動態(tài)擴頻系統(tǒng)中存在的多普勒頻移,選用FFT算法進行頻偏估計,針對FFT頻譜估計在低信噪比下性能不佳的問題,提出基于多普勒頻率補償-頻域匹配的直擴信號快速捕獲算法,改善了低信噪比下碼捕獲性能。使用全數(shù)字非相干超前-滯后延遲鎖定環(huán)實現(xiàn)碼跟蹤,詳細(xì)討論了環(huán)路參數(shù)ζ和BL對碼跟蹤環(huán)路性能的影響。采用科斯塔斯(Costas)載波相位跟蹤方案,推導(dǎo)出環(huán)路鑒相特性,通過仿真驗證科斯塔斯環(huán)可有效的實現(xiàn)載波相位跟蹤。
[Abstract]:The minimum frequency shift keying (MSK) modulation combined with spread spectrum communication system has the advantages of MSK signal, low probability of interception, good confidentiality and strong anti-jamming ability of spread spectrum communication technology. It is used in tactical data link, missile guidance and instruction data transmission. Civil aviation ground-air data link, satellite communication and other fields have been widely used. Therefore, the research of DS MSK modulation and demodulation technology has important theoretical significance and application value. In this paper, pseudorandom sequence characteristics are studied, and Gold codes with good autocorrelation and cross-correlation characteristics are selected as spread spectrum codes. This paper presents a serial direct spread MSK modulation method, deduces the linear expression of the direct spread sequence MSK signal, designs the realization method of the direct spread sequence MSK modulation and despreading demodulation, and verifies the feasibility and performance of the design of the direct spread sequence MSK modulation and despreading demodulation scheme by simulation analysis. The acquisition and tracking techniques of DSSS MSK signals under high dynamic conditions are studied and analyzed in detail. The conventional code acquisition scheme based on matched filter is improved. The dual differential coherent code acquisition method is used to optimize the acquisition performance by balancing the acquisition time and hardware complexity. In view of the Doppler frequency shift existing in the high dynamic spread spectrum system, FFT algorithm is used to estimate the frequency offset, and the FFT spectrum estimation has poor performance under low SNR. A fast acquisition algorithm for DS signals based on Doppler frequency compensation-frequency domain matching is proposed, which improves the performance of code acquisition under low SNR. The full digital incoherent lead-lag delay locking loop is used to realize the code tracking. The influence of the loop parameters 味 and BL on the performance of the code tracking loop is discussed in detail. The characteristic of loop phase detection is deduced by using Kostas (Costas) carrier phase tracking scheme. The simulation results show that Kostas loop can effectively realize carrier phase tracking.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN915.05

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本文編號：2415267