本文選題：外輻射源雷達　切入點：直達波提純　出處：《西安電子科技大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：外輻射源雷達又稱為被動相干定位(PCL)雷達，屬于新體制雷達中的一種。與傳統(tǒng)雷達不同，外輻射源雷達自身不主動發(fā)射電磁波，而是利用各種通信、廣播信號（比如調(diào)頻廣播、電視臺、GSM基站和GPS衛(wèi)星等）作為照射源，被動接收目標(biāo)的反射回波信號實現(xiàn)目標(biāo)探測和成像。從結(jié)構(gòu)上來說，外輻射源雷達屬于雙基地雷達配置，使其不易被敵方發(fā)現(xiàn)，具有較好的抗干擾和抗反輻射導(dǎo)彈能力；并且借助于超高頻和甚高頻的照射源特性，外輻射源雷達具有良好的反隱身和低空探測能力；同時具有便攜、低成本、無需頻譜分配、無電磁污染、無探測盲區(qū)等優(yōu)點。因此，為了應(yīng)對復(fù)雜戰(zhàn)場環(huán)境下的目標(biāo)探測問題，外輻射源雷達目標(biāo)探測已成為一種有效的解決手段，具有重要的研究價值。 本論文主要針對簡易配置的外輻射源雷達目標(biāo)探測系統(tǒng)中的若干具體問題，如直達波提純、雜波相消、參數(shù)估計以及數(shù)據(jù)融合等問題進行深入研究，，所取得的主要研究成果如下： 1、針對復(fù)雜戰(zhàn)場環(huán)境下，接收機周圍可能存在多個照射源，照射源基本信息未知（主要是基站方向和信號波形信息），無法區(qū)分感興趣信號和干擾信號，無法確定目標(biāo)探測中各照射源和目標(biāo)參數(shù)的配對關(guān)系等問題，提出利用信號特性來抑制干擾�？紤]到大部分通信信號都滿足循環(huán)平穩(wěn)的特性，提出利用信號的循環(huán)平穩(wěn)特性估計直達波的方向信息，并抑制其它基站干擾。在目標(biāo)探測階段，推導(dǎo)二階循環(huán)平穩(wěn)和模糊函數(shù)的等價性，提出利用二階共軛循環(huán)平穩(wěn)代替模糊函數(shù)，實現(xiàn)對感興趣信號和目標(biāo)參數(shù)信息的配對。 2、針對實際工程中參考信號包含多徑，常規(guī)外輻射源雷達參考通道和預(yù)警通道都需要雜波相消的問題，提出在預(yù)警通道中利用盲源分離方法直接分離直達波和目標(biāo)回波信號，達到減少運算量和提高目標(biāo)回波信號信噪比的目的。針對常規(guī)盲源分離不適用于外輻射源雷達中病態(tài)矩陣的問題，提出利用循環(huán)平穩(wěn)特性來抑制干擾，達到增強弱目標(biāo)信號的目的，在天線個數(shù)少于信號源個數(shù)的欠定情況，本方法同樣適用。在信號分離階段，針對實際混合信號中還混有噪聲的問題，提出魯棒的斜投影方法來抽取目標(biāo)回波信號。 3、考慮到OFDM信號在同步和抗干擾方面的優(yōu)點，提出基于OFDM信號特性的外輻射源雷達目標(biāo)探測。針對外輻射源雷達中參考信號信息可能無法直接獲取的問題，提出利用信號特性來估計OFDM信號信息。具體考慮到OFDM模糊函數(shù)中的副峰是由導(dǎo)頻的周期性造成的，并且模糊函數(shù)等價于二階循環(huán)平穩(wěn)，提出利用二階循環(huán)平穩(wěn)估計導(dǎo)頻的周期性，從而能夠確定導(dǎo)頻的位置信息，繼而實現(xiàn)雜波信道脈沖響應(yīng)估計和直達波重構(gòu)。 4、針對目前通信廣播系統(tǒng)大都采用OFDM調(diào)制信號，并且支持SFN結(jié)構(gòu)的情況，提出基于OFDM-SFN的外輻射源雷達系統(tǒng)提高目標(biāo)探測的可靠性。但在SFN中，多個信號從不同的方向照射到目標(biāo)，極有可能造成大時延擴展。并且OFDM發(fā)射正交子載波，對載頻頻偏很敏感。針對這兩個問題，在沒有參考信號信息的情況下，提出在接收通道中利用陣列天線把大時延轉(zhuǎn)化為小時延，建立新的張量接收模型，并利用聯(lián)合對角化方法同時估計波束、時延和頻偏三個矩陣變量，解決頻域盲源分離算法在大時延擴展中估計精度不高的問題。 5、針對OFDM-SFN中存在的大時延，提出另一種基于循環(huán)移位和空時編碼的收發(fā)方式，接收端使用單天線就能對抗大時延，達到簡化接收端系統(tǒng)配置的目的。并針對SFN多站定位中，常規(guī)定位算法存在兩步估計誤差的問題，提出基于OFDM信號特性的直接目標(biāo)定位方法。相比常規(guī)的定位方法，本方法能夠獲得更高的定位精度，尤其是在目標(biāo)回波信號低信噪比情況下。
[Abstract]:Passive radar is also called passive coherent location (PCL) radar is a new radar. Unlike conventional radar, passive radar does not actively emit electromagnetic waves, but the use of a variety of communication, broadcast signals (such as FM radio, television, GSM base station and GPS satellite) as radiation source, target detection and imaging echo signal receiving passive target realization. Structurally, passive radar belongs to bistatic radar configuration, it is not easy to be found, has a good anti interference and anti radiation missile capability; radiation source characteristics and with the help of UHF and VHF, passive radar has good anti stealth and low detection capability; it is also portable, low cost, no spectrum allocation, no electromagnetic pollution, the advantages of IOBSS. Therefore, in order to deal with the complex battlefield environment for target detection The target detection of the external radiation source radar has become an effective solution and has important research value.
This thesis focuses on the simple configuration of the passive radar target detection system in some specific issues, such as direct wave purification, clutter cancellation, in-depth study on the issue of parameter estimation and data fusion, the main results are as follows:
1, in view of the complex battlefield environment, the receiver around there may be a number of radiation sources, radiation source unknown basic information (mainly the base station and the signal waveform information), interest can not distinguish between signal and interference signal, unable to determine the matching relationship such problems as the irradiation source and target detection parameters, is proposed to suppress interference using the signal characteristics. Considering that most of the communication signal to meet the cyclostationarity, the paper estimates the direct wave direction information based on cyclostationarity of signals, and suppress other base station interference. In the detection phase, the equivalence of two order cyclostationary and fuzzy function, put forward by two order conjugate cyclostationary instead of fuzzy function. The signal of interest and target parameters matching of information.
2, the reference signal contains multipath in actual engineering for the conventional passive radar reference channel and warning channels need to clutter cancellation problem, proposed direct separation of direct wave and target echo signal in the early warning channel using blind source separation method to reduce the computation and improve the echo signal SNR for. The conventional blind source separation does not apply to external radiation source in the problem of ill conditioned matrix radar, is proposed to suppress the interference using cyclostationarity, to enhance the weak target signal to the less number of antennas less than the number of signal sources, this method is also applicable. In signal separation stage, according to the actual signal is mixed the noise problem, to extract the target echo signal is proposed. The oblique projection method
3, considering the advantages of OFDM signal in synchronization and interference, OFDM signal characteristics of external radiation sources based on radar target detection is proposed. The reference signal information may not be directly access problems for foreign radars, it is proposed to estimate the OFDM signal by using signal characteristics. Specific information considering the OFDM fuzzy function in the side peaks is caused by a periodic pilot, and fuzzy function equivalent to two order cyclostationarity, using two order cyclostationary estimation of periodic pilot, which can determine the location of the pilot, and then realize the clutter channel impulse response estimation and direct wave reconstruction.
4, aiming at the communication and broadcasting system mostly adopts OFDM modulation signal, and the structure of the SFN support, OFDM-SFN is proposed based on the passive radar system to improve the reliability of target detection. But in SFN, a plurality of signal from different direction of irradiation to the target, is likely to cause large delay spread and OFDM emission is. Sub carrier, the carrier frequency offset is very sensitive. To solve these two problems, in the absence of reference signal information, proposed in the receiving channel by using antenna array to delay into time delay, a new tensor receiver model, and uses the joint diagonalization method and beamforming, delay and frequency offset three matrix variables, frequency domain blind source separation algorithm to solve the estimation problem of high precision in large delay spread.
5, according to the large delay of OFDM-SFN, puts forward a cyclic shift and space-time encoding transceiver based on single antenna receiver can withstand large delay, to simplify the receiving end system configuration. And based on the SFN multi station positioning, conventional localization algorithm error estimation problem of the two step forward the direct target location method based on OFDM signal characteristics. Compared with conventional positioning method, this method can obtain higher positioning accuracy, especially at low signal target echo signal SNR.

【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN958

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