發(fā)布時(shí)間：2018-06-20 21:43

  本文選題：射電天線(xiàn) + 評(píng)價(jià)指標(biāo)��； 參考：《國(guó)防科學(xué)技術(shù)大學(xué)》2015年碩士論文

【摘要】：自二十世紀(jì)30年代以來(lái),隨著射電天文望遠(yuǎn)鏡分辨率的不斷提高,射電天文事業(yè)的觀測(cè)頻率范圍已擴(kuò)展到1MHz-1000GHz。然而無(wú)線(xiàn)電事業(yè)也日益壯大,對(duì)無(wú)線(xiàn)電頻譜的需求也越來(lái)越大,影響了射電天文的觀測(cè),阻礙了射電天文事業(yè)的發(fā)展。事實(shí)表明射電天文觀測(cè)受到的干擾越來(lái)越多都是來(lái)自地面的,其中數(shù)全球衛(wèi)星導(dǎo)航信號(hào)最為常見(jiàn)。本文基于利用射電天線(xiàn)觀測(cè)21cm譜線(xiàn)時(shí)容易受到GPS L2信號(hào)干擾這個(gè)研究背景,采用單輔助天線(xiàn)方法,針對(duì)以下兩個(gè)射電天線(xiàn)抗干擾中常見(jiàn)的問(wèn)題進(jìn)行了研究:現(xiàn)有評(píng)價(jià)指標(biāo)對(duì)抗干擾性能評(píng)價(jià)方面的局限和主輔天線(xiàn)接收導(dǎo)航信號(hào)時(shí)存在的分?jǐn)?shù)時(shí)延差會(huì)影響抗干擾方法的性能。針對(duì)評(píng)價(jià)指標(biāo)的局限性,文中結(jié)合抗干擾中幾種常用評(píng)價(jià)指標(biāo),通過(guò)理論推導(dǎo)出了兩個(gè)評(píng)價(jià)指標(biāo):信號(hào)衰減度Gs和干擾抑制度GI,簡(jiǎn)單直接的分別對(duì)抗干擾后信號(hào)中射電天文信號(hào)和導(dǎo)航干擾功率上的變化量做出了統(tǒng)計(jì),準(zhǔn)確地評(píng)價(jià)了抗干擾算法性能。針對(duì)主輔天線(xiàn)中導(dǎo)航干擾存在時(shí)延差的問(wèn)題,采用了最優(yōu)化方法和AP窗方法,對(duì)分?jǐn)?shù)時(shí)延固定的情況設(shè)計(jì)了兩種精度較高的分?jǐn)?shù)時(shí)延FIR濾波器,時(shí)延誤差高達(dá)10-7量級(jí)。最后提出了基于時(shí)延匹配的自適應(yīng)濾波方法,通過(guò)計(jì)算機(jī)仿真,探索并比較了LMS類(lèi)算法和基于時(shí)延匹配的LMS類(lèi)算法性能的同時(shí),證明了后者在一定程度上提高了LMS類(lèi)算法的抗干擾性能,還驗(yàn)證了提出評(píng)價(jià)指標(biāo)的有效性。
[Abstract]:Since the 1930s, with the increasing resolution of radio telescopes, the observational frequency range of radio astronomy has been extended to 1MHz-1000GHz. However, the radio industry is growing stronger and the demand for radio spectrum is increasing, which affects the observation of radio astronomy and hinders the development of radio astronomy. The facts show that more and more interference of radio astronomical observation is from the ground, among which, several global satellite navigation signals are the most common. Based on the research background that the radio antenna is easy to be disturbed by 21cm L2 signal, a single auxiliary antenna method is used in this paper. The following two common problems in radio antenna anti-jamming are studied: the limitation of existing evaluation indexes on anti-jamming performance and the difference in fractional delay between main and auxiliary antennas in receiving navigation signals will affect the performance of anti-jamming methods. Aiming at the limitation of evaluation index, this paper combines several commonly used evaluation indexes in anti-jamming. Through the theoretical derivation of two evaluation indexes: signal attenuation (Gs) and interference suppression (Gi), the variations of radio astronomical signal and navigation interference power in the anti-jamming signal are simply and directly analyzed. The performance of anti-jamming algorithm is evaluated accurately. Aiming at the problem of delay difference in navigation interference between main and auxiliary antennas, the optimization method and AP window method are used to design two kinds of fractional delay Fir filters with high precision when fractional delay is fixed. The delay error is as high as 10-7 order of magnitude. Finally, an adaptive filtering method based on delay matching is proposed. By computer simulation, the performance of LMS class algorithm and delay matching based LMS class algorithm are explored and compared. It is proved that the latter improves the anti-jamming performance of LMS class algorithm to some extent, and the validity of the proposed evaluation index is also verified.
【學(xué)位授予單位】：國(guó)防科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P111.44;TN967.1

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