發(fā)布時(shí)間：2018-01-22 08:30

  本文關(guān)鍵詞： 全球?qū)Ш叫l(wèi)星系統(tǒng) 弱信號(hào)環(huán)境 偽碼設(shè)計(jì) 捕獲 干擾分析　出處：《華中科技大學(xué)》2013年博士論文　論文類型：學(xué)位論文

【摘要】：全球?qū)Ш叫l(wèi)星系統(tǒng)(Global Navigation Satellite System, GNSS)在國(guó)防和經(jīng)濟(jì)建設(shè)中的重要性日益凸顯,許多國(guó)家和地區(qū)都在積極構(gòu)建擁有自主知識(shí)產(chǎn)權(quán)的GNSS系統(tǒng)。在系統(tǒng)構(gòu)建過程中,如何提高GNSS系統(tǒng)的可靠性、完好性及定位精度始終是研究的主要目標(biāo),特別是近年來隨著GNSS應(yīng)用范圍的擴(kuò)展,在信號(hào)衰減嚴(yán)重的弱信號(hào)應(yīng)用環(huán)境中如何提高定位可靠性受到了人們的普遍關(guān)注,成為當(dāng)前GNSS研究的熱點(diǎn)。 在諸多影響弱信號(hào)環(huán)境下GNSS定位性能的因素中,信號(hào)體制和接收技術(shù)是其中最重要的兩個(gè)�？紤]到偽碼設(shè)計(jì)是信號(hào)體制設(shè)計(jì)的核心環(huán)節(jié),在很大程度上決定了GNSS信號(hào)性能；而捕獲技術(shù)則是弱信號(hào)接收技術(shù)的關(guān)鍵,因此本文主要針對(duì)GNSS偽碼設(shè)計(jì)和弱信號(hào)捕獲技術(shù)兩個(gè)關(guān)鍵問題進(jìn)行研究,以提高弱信號(hào)環(huán)境下GNSS系統(tǒng)的定位性能。本文的創(chuàng)新性主要體現(xiàn)在以下幾點(diǎn)： 1)針對(duì)弱信號(hào)環(huán)境下強(qiáng)多址干擾引起的GNSS信號(hào)誤捕獲問題,提出了一種能夠明顯改善弱信號(hào)捕獲性能的非等長(zhǎng)偽碼設(shè)計(jì)方法。這種非等長(zhǎng)偽碼設(shè)計(jì)方法克服了長(zhǎng)偽碼存在的捕獲時(shí)間過長(zhǎng)及短偽碼存在的互相關(guān)隔離度過低的問題,通過令同一系統(tǒng)不同信號(hào)間偽碼碼長(zhǎng)互質(zhì),有效的降低了偽碼互相關(guān)值,改善了弱信號(hào)環(huán)境下的信號(hào)捕獲性能,實(shí)現(xiàn)了捕獲時(shí)間和捕獲性能的折衷。為了充分說明非等長(zhǎng)偽碼設(shè)計(jì)方法的優(yōu)勢(shì),本文從時(shí)域和頻域兩方面闡述了非等長(zhǎng)碼改善弱信號(hào)捕獲性能的原理,并對(duì)該偽碼設(shè)計(jì)方法對(duì)弱信號(hào)捕獲的改善作用進(jìn)行分析,之后通過仿真驗(yàn)證了理論分析的正確性。結(jié)果表明,在相同接收條件下,采用非等長(zhǎng)偽碼設(shè)計(jì)時(shí)信號(hào)的檢測(cè)概率明顯高于相當(dāng)長(zhǎng)度等長(zhǎng)碼情況。對(duì)于弱信號(hào)情況下多址干擾引起的碼跟蹤誤差,非等長(zhǎng)偽碼設(shè)計(jì)亦有明顯的改善效果。非等長(zhǎng)偽碼設(shè)計(jì)方法使多址干擾引起的碼跟蹤環(huán)鑒別器輸出誤差呈現(xiàn)隨機(jī)變化的特點(diǎn),這樣碼跟蹤環(huán)路濾波器可方便濾除多址干擾引起的碼跟蹤誤差,使碼跟蹤精度得以提高。理論分析和仿真結(jié)果驗(yàn)證了非等長(zhǎng)碼對(duì)弱信號(hào)環(huán)境碼跟蹤精度的改善作用。 2)為了克服獨(dú)立捕獲模式下因后相關(guān)處理增益較低而無(wú)法保證弱信號(hào)可靠捕獲的問題,提出了一種改進(jìn)的差分累加后相關(guān)處理技術(shù)。論文首先對(duì)獨(dú)立捕獲模式三種常見的后相關(guān)處理技術(shù)(即相干累加、非相干累加和差分累加)進(jìn)行分析對(duì)比,得出因差分累加具有相位解旋的作用且無(wú)明顯的平方損耗,同時(shí)對(duì)數(shù)據(jù)位翻轉(zhuǎn)不太敏感,故更適用于弱信號(hào)環(huán)境GNSS信號(hào)捕獲的結(jié)論。之后詳細(xì)分析了導(dǎo)航數(shù)據(jù)翻轉(zhuǎn)和載波頻率估計(jì)誤差對(duì)傳統(tǒng)差分后相關(guān)技術(shù)處理增益造成的影響,并在此基礎(chǔ)上針對(duì)弱信號(hào)環(huán)境提出一種改進(jìn)的半比特頻率補(bǔ)償差分后相關(guān)技術(shù)。該技術(shù)通過在捕獲環(huán)節(jié)引入多普勒頻差補(bǔ)償,消除了多普勒頻率估計(jì)偏差引起的處理?yè)p耗,并通過半比特處理技術(shù)消除了相干積分環(huán)節(jié)數(shù)據(jù)翻轉(zhuǎn)可能帶來的的處理?yè)p耗,使弱信號(hào)捕獲概率明顯提高。理論分析和仿真結(jié)果表明,改進(jìn)的后相關(guān)差分累加處理技術(shù)捕獲性能明顯優(yōu)于傳統(tǒng)差分累加技術(shù),具有更高的捕獲靈敏度和可靠性。 3)針對(duì)弱信號(hào)情況下非白射頻干擾對(duì)信號(hào)的捕獲和跟蹤性能影響較大且難以分析的問題,提出了一種系統(tǒng)的非白干擾的白化分析方法。該方法將非白干擾通過相應(yīng)的白化系數(shù)轉(zhuǎn)化成易于分析的等效白噪聲,簡(jiǎn)化了非白干擾的分析過程�？紤]到非白干擾對(duì)捕獲及載波跟蹤性能的影響主要體現(xiàn)在即時(shí)通道,本方法在分析非白干擾對(duì)即時(shí)通道的影響時(shí),通過首先推導(dǎo)白噪聲分析模型,之后直接將非白干擾的等效白噪聲替換已有模型白噪聲的方法,簡(jiǎn)化了非白干擾對(duì)相關(guān)輸出信噪比和載波跟蹤精度影響的分析過程,使非白干擾的影響作用更直觀；對(duì)于非白干擾對(duì)碼跟蹤的影響,則充分考慮了相干早遲處理碼跟蹤環(huán)和非相干早遲處理碼跟蹤環(huán)的特點(diǎn),通過引入新的參數(shù),完成了非白干擾的白化分析過程。以Betz經(jīng)典的碼跟蹤分析方法作為參照,將本方法與現(xiàn)有的非白干擾分析方法的分析方法進(jìn)行對(duì)比,發(fā)現(xiàn)本方法仿真結(jié)果與Betz方法的分析結(jié)果更趨一致,然而本方法的分析過程卻較Betz經(jīng)典的碼跟蹤分析簡(jiǎn)化了許多,因而更便于應(yīng)用。
[Abstract]:The global navigation satellite system (Global Navigation Satellite System, GNSS) on the importance of national defense and economic construction has become increasingly prominent in many countries and regions are actively building GNSS system with independent intellectual property rights. In the process of the construction of the system, how to improve the reliability of the GNSS system, the integrity and the positioning accuracy is always the main goal of the research. Especially in recent years, with the expansion of the application scope of the GNSS, on how to improve the reliability of positioning signal attenuation has received extensive attention in the application of weak signal environment is serious, has become the research hotspot of GNSS.
In the factors of the positioning performance of GNSS signal environment influenced the weak, signal system and receiving technology is one of the most important two. Considering the pseudo code design is the core part of signal system design, largely determines the performance of GNSS signal; and the capture technology is the key technology of weak signal reception, so this paper the main techniques of the two key problems in design of GNSS pseudo code capture and weak signal are studied, in order to improve the positioning performance of the GNSS system in weak signal environment. The innovation of this paper is mainly reflected in the following points:
1) according to the error of GNSS signal acquisition problem in weak signal environment caused by strong Mai, a weak signal acquisition can significantly improve the performance of non isometric pseudo code design method. The design method of long pseudo code to overcome the isolation of low cross-correlation of long PN code acquisition time are too long and short PN code the existence of the problem, by making the same system among different signals PN code length relatively prime and effectively reduce the pseudo code cross-correlation values, improve the signal acquisition performance in weak signal environment, realize the acquisition time and compromise capture performance. In order to fully explain the design method of non isometric PN advantage, this paper from the two aspects of the time domain and frequency domain describes the non isometric code improvement principle of weak signal acquisition performance, and analyze the effect to improve the weak signal acquisition of the PN code design method is verified by simulation after theoretical analysis is correct . the results show that under the same conditions, the detection probability of receiving, non isometric pseudo code design signal was significantly higher than that of equivalent length equal code. For weak signal in the case of multiple access interference caused by code tracking error, the unequal pseudo code design also has obvious improvement effect. The characteristics of non long pseudo code design method the multiple access interference code tracking loop discriminator output error caused by random variation of the present, this code tracking loop filter can filter the multiple access interference caused by code tracking error, the code tracking accuracy can be improved. Theoretical analysis and simulation results prove the non equal length code tracking accuracy improvement in weak signal environment.
2) in order to overcome the capture mode for independent after the processing gain is lower and can not guarantee the reliability of weak signal capture problem, put forward the related processing technology of an improved differential accumulation. Firstly, three kinds of acquisition mode after processing technology of independent (i.e., coherent, non coherent and differential the cumulative) were compared, obtained by the phase difference accumulation has the effect of untwisting and square loss obviously, and the data bit less sensitive, so it is more suitable for weak signal environment GNSS signal acquisition and conclusion. The detail analysis of the navigation data switching and carrier frequency estimation error on the performance of the traditional difference related technical processing gain caused, and based on the weak signal environment and proposes an improved half bit frequency compensation difference and related technology. The technology through the link for the capture of Doppler frequency Error compensation, eliminates the estimation of Doppler frequency deviation caused by the loss of processing, and through the half bit processing techniques of coherent integral data flip may bring loss to eliminate the processing, the weak signal acquisition probability is improved. Theoretical analysis and simulation results show that the difference of improvement after accumulating processing technology acquisition performance is better than the traditional difference points accumulated technology, has a higher acquisition sensitivity and reliability.
3) for radio frequency interference on signal acquisition and tracking performance of large and difficult to analyze the problem of weak signal condition, proposed a system of non white interference whitening analysis method. The non white interference through the whitening coefficients corresponding into easy to analysis effect of white noise, simplified analysis the process of non white interference. Considering the effect of non white interference on acquisition and carrier tracking performance is mainly reflected in the real-time channel, this method in the analysis of non white interference effects on instant channel, through the first derivation of white noise analysis model, after the equivalent white noise interference model to replace the existing non white noise the method simplifies the analysis process, influence of non white interference on the output signal-to-noise ratio and carrier tracking accuracy, the effect of non white interference is more intuitive; for non white interference on code tracking, is sufficient Considering the coherent early late processing code tracking loop and noncoherent early late processing characteristics of the code tracking loop, by introducing new parameters, completed the albino non white interference analysis process. Taking Betz classic code tracking analysis method as a reference, comparative analysis method with the existing non white interference analysis method the results of the simulation results with Betz method is more consistent, but the analysis process of this method is compared with the classic Betz code tracking analysis simplified a lot, so it is more easy to use.

【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：TN96.1

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