【摘要】：近年來,具有優(yōu)良的抗干擾性、低截獲概率以及可兼容性等諸多優(yōu)點的跳頻信號受到了國內(nèi)外學者的廣泛關注,而且被軍事和民用通信等系統(tǒng)廣泛采用,有效的參數(shù)估計是保證信息準確傳輸?shù)年P鍵,也是跳頻通信研究中的熱點和難點。諸多研究表明雷達、地震、生物工程等領域中的雜波干擾或?qū)嶋H噪聲均服從?穩(wěn)定分布,這類分布的概率密度函數(shù)具有顯著尖峰脈沖狀波形和較厚拖尾,且不存在有限的二階矩和高階矩。在?穩(wěn)定分布噪聲下,通常的基于高斯模型的信號處理方法會出現(xiàn)性能降低甚至失效的情況。因此,在該類噪聲背景下,研究切實可行的跳頻信號參數(shù)估計方法對于跳頻通信的發(fā)展具有重要意義。本文針對?穩(wěn)定分布噪聲下的跳頻信號參數(shù)估計進行了研究,取得的主要成果如下:1.對傳統(tǒng)時頻分析方法短時傅里葉變換窗寬的選擇進行了研究。引入Renyi熵的方法評價時頻分析性能的優(yōu)劣,通過確定最小熵值獲得最佳窗寬。結(jié)合分數(shù)低階方法,與傳統(tǒng)短時傅里葉變換相比,基于Renyi熵的短時傅里葉變換更能準確估計?穩(wěn)定分布噪聲下跳頻信號的跳頻周期,并且提高了跳變時刻、跳頻頻率的估計精度。2.對二次型時頻分析方法中的交叉項抑制問題進行了研究。針對傳統(tǒng)非線性時頻分析方法在處理跳頻信號時,會出現(xiàn)嚴重的交叉項和參數(shù)估計精度降低等問題,簡要分析了交叉項和自項的位置,接著引入RGK時頻分析方法,根據(jù)信號的不同自適應地選擇最優(yōu)高斯核函數(shù),從而有效抑制遠離原點的交叉項并保留原點附近的自項。實驗結(jié)果表明,該方法具有良好的時頻分辨率和參數(shù)估計性能。3.對基于廣義柯西分布的脈沖噪聲抑制方法進行了研究。提出了一種WMGC濾波器,利用最大似然估計理論得到最佳樣本值,并結(jié)合可靠性加權原則,根據(jù)代價函數(shù)最小準則求取最佳權系數(shù),從而選取最接近期望值的樣本。隨后與RGK時頻分析方法相結(jié)合,提出了WR(WMGC-RGK)方法,并對?穩(wěn)定分布噪聲下的跳頻信號進行參數(shù)估計。分別與基于分數(shù)低階及Myriad濾波器的時頻分析方法進行仿真對比,WR方法在?穩(wěn)定分布噪聲中具有良好的魯棒性和優(yōu)良的參數(shù)估計性能。
[Abstract]:In recent years, frequency hopping signal, which has many advantages such as good anti-jamming, low probability of intercept and compatibility, has been widely concerned by scholars at home and abroad, and has been widely used in military and civil communication systems. Effective parameter estimation is not only the key to ensure the accurate transmission of information, but also the hot and difficult point in the research of frequency hopping communication. Many studies have shown that clutter interference or actual noise in radar, earthquake, bioengineering and other fields obeys? Stable distribution, the probability density function of this kind of distribution has significant spike pulse shape and thick trailing, and there are no finite second-order moments and higher-order moments. Yes? Under stable distributed noise, the performance of the usual signal processing methods based on Gao Si's model will be degraded or even failed. Therefore, under the background of this kind of noise, it is of great significance for the development of frequency-hopping communication to study feasible parameter estimation methods of frequency-hopping signals. This article is aimed at? The parameter estimation of frequency hopping signal under stable distributed noise is studied. The main results obtained are as follows: 1. The selection of window width of short-time Fourier transform (STFT) based on traditional time-frequency analysis method is studied. The method of Renyi entropy is introduced to evaluate the performance of time-frequency analysis, and the optimal window width is obtained by determining the minimum entropy value. Compared with the traditional short-time Fourier transform (STFT), the short-time Fourier transform (STFT) based on Renyi entropy is better than the traditional short-time Fourier transform (STFT). The frequency hopping period of the frequency hopping signal under stable distributed noise is stable, and the estimation precision of the frequency hopping frequency is improved when the hopping time is improved. 2. The suppression of cross-term in quadratic time-frequency analysis is studied. In order to deal with frequency hopping signals, the traditional non-linear time-frequency analysis method will appear serious cross-term and parameter estimation precision reduction and so on. The position of cross-term and self-term is analyzed briefly, and then RGK time-frequency analysis method is introduced. The optimal Gao Si kernel function is selected adaptively according to the different signals, so that the cross term far away from the origin is effectively suppressed and the self term near the origin is preserved. Experimental results show that the proposed method has good time-frequency resolution and parameter estimation performance. 3. The impulse noise suppression method based on generalized Cauchy distribution is studied. In this paper, a WMGC filter is proposed. The optimal sample value is obtained by using the maximum likelihood estimation theory, and the optimal weight coefficient is obtained according to the minimum criterion of the cost function according to the principle of reliability weighting, so as to select the sample closest to the expected value. Then, combined with the RGK time-frequency analysis method, the WR (WMGC-RGK) method is proposed. The parameters of frequency hopping signals with stable distributed noise are estimated. Compared with the time-frequency analysis method based on fractional low-order and Myriad filter respectively, the WR method is in? Stable distributed noise has good robustness and good parameter estimation performance.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN914.41;TN911.23

【參考文獻】

相關期刊論文 前1條

1 龍俊波;汪海濱;查代奉;;基于穩(wěn)定分布噪聲的分數(shù)低階自適應時頻分布[J];計算機工程;2011年18期

，

本文編號：2447892