【作者】 李志；

【导师】 刘人杰；

【作者基本信息】 大连海事大学 ， 通信与信息系统， 2012， 博士

【摘要】 本文主要研究的是瞬态检测基本理论及其传输技术。主要利用的是确知基带数字信号码元波形与加性噪声干扰在瞬态特征上的差异来进行信号检测的,能抗强加性噪声干扰。与传统的统计积分检测方法不同,瞬态检测理论主要采用干扰微分方程的方法来进行信号检测。利用测知接收的混合信号和干扰函数值来列出仅关于干扰函数为变量的微分方程,通过测量的干扰初值可先求解出所列干扰微分方程的变量,然后用接收的混合信号减去已求解出的干扰,即可恢复出受检信号。瞬态检测理论所列微分方程具有在混合测知信号中消除确知受检信号码元的特点,所以受检码元信号函数的选择必须使其在微分方程中所形成的多项式和为零,通过对微分方程的分析和研究推导出瞬态检测码元函数为te-at的形式,根据瞬态检测理论建立了一、二阶干扰微分方程,并给出了数值解法,同时研究设计了适合数字信号处理器模拟实验的软件和硬件实验仿真系统,通过实验验证了瞬态检测理论的正确性。码间干扰和邻道干扰的抑制是瞬态检测理论应用于实际通信必须要解决的问题,通过理论推导和分析可以发现干扰微分方程具有抑制码间干扰的能力。由于瞬态检测所使用的码元信号函数ta-at的频率成分较为丰富,在消除邻道干扰所使用的锐截止滤波器会造成码元的波形畸变而对瞬态检测非常不利,所以根据所选码元函数的特点,采取频谱截断补偿法来消除邻道干扰,并且能基本无失真的恢复出受检信号的频谱。首先利用单个无任何干扰的码元经过快速傅立叶变换(FFT)后截断,再用截断点以外的频谱和截断点以内的点相比得到一系列的补偿系数,将这些系数存储在数字信号处理器的存储器内,然后再用数字信号处理器对实际接收的信号进行采样、FFT、截断,通过已存储的系数和截断内点的频谱计算来完全恢复出截断后的受检信号频谱,经傅立叶反变换(IFFT)后得到不含邻道干扰的受检信号,并以此建立了抑制邻道干扰的实验系统,实验证明检测结果比简单截断处理方法有了很大的改进。高速数据传输也是数据通信追求的目标之一,根据抑制邻道干扰的系数补偿方法延伸推导出在窄带内提高传输速率的补偿计算方法,并且在保证瞬态检测准确率和不增加带宽的情况下,通过准周期频谱系数的补偿方法可以使传输速率提高4倍左右。该方法已通过对车载725单边带电台进行数据通信的应用设计和实验,由于载信码元的特殊性和检测方法的独特性,使其能在高速数据传输、抗强加性同频噪声干扰和保密通信中发挥重要的作用。OFDM系统是未来3G和4G通信技术所要采用的“最后一公里”接入技术,利用瞬态检测理论阐述的某些方法来改善ODFM子信道中抑制邻道干扰的性能,从而达到在OFD系统中提高传输效率、降低误码率的目的。本文所研究的瞬态检测理论具有与传统检测方法不同的检测机理,它的原理可以不受仙农信道容量公式的限制,在对抗强加性噪声或同频干扰上有着无法比拟的优越性,是数字信号检测理论的一个创新,为弱确知信号的检测理论和超高速数据传输开辟了一个新的研究领域,同时由于其检测方法的独特性和抗强同频干扰的特点,又可用于保密通信和电子对抗,具有较高的学术价值和经济价值。更多还原

【Abstract】 This paper mainly studies the transient detection theory which is expounded as a new method to detect signal by the transient characteristic difference between the base band digital signal symbol waveforms and the additive noise. It varies from the traditional statistical detection methods in strong noise, which is mainly use of differential equation method to perform signal detection. First, the interference differential equation is given out only containing the measured received mixed signal and interference function, which have eliminated the detected signal. Second, the solution of interference can be solved through the interference differential equation which is already gotten. Finally, the detected signal can be recovered by the received mixed signal subtracting the interference which has been gotten from the interference differential equation.The base band signal function must be eliminated in the differential equation based on transient detection theory, so the signal function should be selected to make its polynomial summation in the differential equations of polynomial equals zero, then, te"at is to be selected as signal function based on the analysis and study through differential equation deducing, and the solution which make use of numerical analysis is given out from the first-rank interference differential equation, the simulation software and hardware system is designed for digital signal processor and the correctness of the theory is verified through those experiments.The problems of adjacent channel interference and intersymbols interference must be solved in the process of transient detection theory which is applied in the practical communication. Because frequency in the signal function of te-αt is relatively rich, the waveform of signal is distorted when it is through sharp cutoff filter. That will cause high Pe rate in transient detection, it is very adverse for detection. According to the characteristics of selected symbol function, the method about spectrum truncation compensation is taken to eliminate the adjacent channel interference and recovery of signal spectrum which should be detected. First, using a single without any interference symbol will be processed in FFT, then a series of coefficients will be gotten through comparing the outside points and the inside points of truncation, these coefficients are stored in the memory of digital signal processor. Finally, the digital signal processor processes sample of the actual signal with FFT, truncation and the all detected signal spectrum can be recovered after calculating with stored coefficients and inner points which is kept after truncation, so the source signal containing no adjacent channel interference can be gotten from Inverse Fast Fouier Transform (IFFT).The method of transient detection is proved entirely correct based on those above, the experimental system to eliminate adjacent channel interference is established from what is expounded above.Quicker speed data transmission is one of the goals in data communication. A new method which improve transmission rate can be derived in virtue of coefficient comp-ensation calculation method to inhibit the interference of adjacent channel in a narrow band, the transmission rate can be improved about 4 times by the transient detection method and does not increase the bandwidth in the same Pe. The method has applied SSB in 725 wireless basestation on vehicles. The transient detection method plays an important role in high speed data transmission, anti strong same frequency interference and secure communication.OFDM is a communication technology which is also a communication technology used for 3G and 4G in the future. The performance of inhibition of adjacent channel interference in the sub-carrier channel of OFDM will be improved by aid of characters of transient detection method in determinate weak signal detection. Then, the purpose to improve the transmission efficiency and reduce Pe will be realized in the ODFM sub-channel.There is entirely difference principle between the transient detection theory and the traditional detection method. The transient detection theory has incomparable superiority in the fight against strong noise and interference in the same frequency, its principle can not be limited by Shannon channel capacity formula because the transient character is adopted based on interference differential equation. It is a breakthrough in digital signals detection area. It opens up a new field of study for weak known signal detection theory and high speed data transmission. Because the transient detection theory has unique characteristics in anti strong interference of the same frequency, it also can be used in secure communication and electronic countermeasure at the same time. It has extremely high academic and economic value.更多还原