论文部分内容阅读
信号是与一种物理现象相关连、并传输数据的时间变量。按物理量分,有电压信号、气压信号、光信号、声信号和磁信号等;按时间特征分,有模拟信号、数字信号和脉冲信号等。然而就信号的一般规律而言,信号可分为确定性信号和随机信号两大类。确定性信号是可以用确定的数学关系式来描述的信号。随机信号则是不能用确定的数学关系描述的信号。信号分析就是基于某些数学原理如博里叶变換、数论变換,用模拟计算机或专用模拟机、数字计算机或专用数字机对信号本身或信号之间的性质、规律进行分析。具体说,对于确定性信号的信号分析就是找出能描述这一信号特征变化的规律;对于随机信号则是找出描述其统计规律的一些数字特征,如均方值(均值和方差)、概率密度函数、自相关函数、功率谱密度函数等。
A signal is a temporal variable that is associated with a physical phenomenon and transmits data. Divided by the physical quantity, there are voltage signals, pressure signals, optical signals, acoustic signals and magnetic signals; according to the time characteristics of points, there are analog signals, digital signals and pulse signals. However, in terms of the general law of the signal, the signal can be divided into two categories: deterministic signal and random signal. A deterministic signal is a signal that can be described by a defined mathematical relationship. A random signal is a signal that can not be described by a definite mathematical relationship. Signal analysis is based on some mathematical principles such as Bole-leaf transformation, number theory transformation, using analog computers or special-purpose simulators, digital computers or special digital machines to analyze the nature of the signal itself or the law. Specifically, the signal analysis of a deterministic signal is to find out the law that can describe the variation of the signal characteristic. For a random signal, some digital features describing its statistical law are found, such as the mean square (mean and variance), probability Density function, autocorrelation function, power spectral density function and so on.