發(fā)布時(shí)間：2018-05-06 14:43

  本文選題：北斗二代衛(wèi)星導(dǎo)航系統(tǒng) + 定長(zhǎng)相干積分遍歷/非遍歷�。� 參考：《廈門大學(xué)》2014年碩士論文

【摘要】：隨著北斗二代衛(wèi)星導(dǎo)航系統(tǒng)的成功組網(wǎng)并投入使用,對(duì)能夠支持北斗二代衛(wèi)星導(dǎo)航系統(tǒng)的用戶端導(dǎo)航定位設(shè)備的研發(fā)需求也日益迫切。由于北斗二代衛(wèi)星導(dǎo)航系統(tǒng)的B1信號(hào)中引入了二次編碼調(diào)制技術(shù),在提高互相關(guān)性能的同時(shí)也給衛(wèi)星信號(hào)的捕獲方法帶來了挑戰(zhàn),NH碼的調(diào)制使得每間隔1ms就有可能產(chǎn)生符號(hào)位跳變,這就限制了B1信號(hào)的相干積分時(shí)長(zhǎng),嚴(yán)重影響了北斗二代衛(wèi)星B1信號(hào)的捕獲性能,因此本文應(yīng)用了定長(zhǎng)相干積分遍歷/非遍歷的并行碼相位搜索的粗捕獲算法,實(shí)現(xiàn)了對(duì)北斗二代衛(wèi)星B1信號(hào)的長(zhǎng)時(shí)間相干積分捕獲,提高了B1信號(hào)的捕獲性能。粗捕獲得到的載波頻率估計(jì)精度通常無法滿足跟蹤環(huán)路的要求,需進(jìn)行精細(xì)頻率捕獲,本文針對(duì)B1信號(hào)的特點(diǎn),提出基于頻域插值的載波頻率估計(jì)算法,在粗捕獲之后,對(duì)B1信號(hào)進(jìn)行精頻捕獲,改善載波頻率估計(jì)精度。 本文首先對(duì)北斗二代衛(wèi)星B1信號(hào)的結(jié)構(gòu)進(jìn)行分析,針對(duì)NH碼的自身特點(diǎn)設(shè)計(jì)了定長(zhǎng)相干積分遍歷的并行碼相位搜索算法,然后對(duì)該算法進(jìn)行了仿真,仿真結(jié)果驗(yàn)證了該算法的正確性,在相干積分長(zhǎng)度為4ms的情況下,可以捕獲載噪比為37dB·Hz的B1信號(hào)。接著針對(duì)該算法計(jì)算量較大的缺點(diǎn)進(jìn)行了改進(jìn),提出了定長(zhǎng)相干積分非遍歷的并行碼相位搜索算法,以犧牲一定的捕獲性能為代價(jià)減小計(jì)算量,并仿真了不同搜索次數(shù)算法在最差情況下的捕獲性能。 其次,粗捕獲得到的載波多普勒頻率精度較低,需要進(jìn)行精頻捕獲,針對(duì)B1信號(hào)的精頻捕獲問題,本文提出基于頻域插值的載波頻率估計(jì)算法,并對(duì)該算法進(jìn)行仿真,仿真結(jié)果顯示該算法成功改善了低信噪比環(huán)境下載波多普勒頻率的估計(jì)精度。本文還使用模擬器產(chǎn)生的B1信號(hào)對(duì)基于頻域插值的載波頻率估計(jì)算法進(jìn)行測(cè)試,驗(yàn)證該算法對(duì)于改善低信噪比環(huán)境下載波頻率估計(jì)精度的有效性。 最后本文對(duì)于定長(zhǎng)相干積分20次搜索遍歷/10次搜索非遍歷的并行碼相位搜索的粗捕獲算法在FPGA平臺(tái)上進(jìn)行了硬件實(shí)現(xiàn),并使用了三個(gè)不同場(chǎng)景的真實(shí)北斗二代衛(wèi)星B1信號(hào)進(jìn)行測(cè)試,驗(yàn)證了硬件實(shí)現(xiàn)的正確性。
[Abstract]:With the successful networking and application of the Beidou second generation satellite navigation system, the research and development of the user terminal navigation and positioning equipment which can support the Beidou second generation satellite navigation system is becoming more and more urgent. Because of the introduction of quadratic coded modulation technology in the B1 signal of Beidou second generation satellite navigation system, While improving the performance of cross-correlation, it also brings challenges to the acquisition method of satellite signal. The modulation of NH code makes it possible for 1ms to produce symbol bit jump at every interval, which limits the time of coherent integration of B1 signal. The acquisition performance of Beidou second generation satellite B1 signal is seriously affected. In this paper, the coarse acquisition algorithm of parallel code phase search based on constant coherence integral ergodic and non-ergodic is used. The long time coherent integral acquisition of Beidou second generation satellite B1 signal is realized, and the capture performance of B1 signal is improved. The accuracy of carrier frequency estimation from coarse acquisition can not meet the requirements of tracking loop, so fine frequency acquisition is needed. In this paper, a carrier frequency estimation algorithm based on interpolation in frequency domain is proposed, which is based on the characteristics of B1 signal. Precision frequency acquisition of B1 signal is carried out to improve the accuracy of carrier frequency estimation. In this paper, the structure of Beidou second generation satellite B1 signal is analyzed, and the phase search algorithm of parallel code is designed according to the characteristic of NH code, and then the algorithm is simulated. The simulation results show that the algorithm is correct, and the B1 signal with 37dB Hz can be captured when the coherent integral length is 4ms. Then, aiming at the disadvantage of the algorithm, a phase search algorithm of parallel code is proposed, which can reduce the computational complexity at the expense of certain capture performance. The capture performance of different search times is simulated in the worst case. Secondly, the accuracy of carrier Doppler frequency obtained by coarse acquisition is low, so fine frequency acquisition is needed. Aiming at the problem of fine frequency acquisition of B1 signal, a carrier frequency estimation algorithm based on interpolation in frequency domain is proposed in this paper, and the algorithm is simulated. Simulation results show that the proposed algorithm can improve the estimation accuracy of carrier Doppler frequency in low SNR environment. This paper also tests the carrier frequency estimation algorithm based on interpolation in frequency domain by using the B1 signal generated by the simulator to verify the effectiveness of the algorithm in improving the accuracy of carrier frequency estimation in low SNR environment. Finally, the rough acquisition algorithm of parallel code phase search based on FPGA platform is implemented on the platform of FPGA, which has 20 traversal / 10 non-ergodic parallel code phase search algorithms with fixed coherence integral. The true Beidou second generation satellite B1 signal of three different scenarios is used to verify the correctness of the hardware implementation.
【學(xué)位授予單位】：廈門大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN965.5

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本文編號(hào)：1852716