( 4 ) after factual characteristics of targets and clutter have been studied , an approach of radar signal detection based on factual has been given and analyzed deeply , the influence caused by different window length , signal to clutter ratio ( scr ) and clutter background has been analyzed , then the monte - carlo simulation method has been used to analyze the detection performances ( 4 )研究了目标和杂波的分形特性,深入研究了基于分形的雷达信号检测方法,分析了不同滑窗长度、不同信杂比和杂波背景变化情况对回波分形维数的影响,采用蒙特卡罗仿真分析该检测器的性能。
On the premise that the basal transducer layout was designed according to the requirements of deep - sea exploring surroundings and technology on the basis of the hardware structure and data collecting ways of interferometric sonar , the echo signal by energy relativity search is analyzed and calculated , altitude data of the tiny terrain on the seabed under real - time irradiation of ultrasonic is gained as to provide parameters of best cutting depth for intellectualization of the seabed mining vehicle timely and promptly 摘要在相干声纳硬件结构及数据采集方式的基础上，结合具体的深海钴结壳探测环境和技术要求，确定了换能器基本布局，探讨了信号采集与处理方法，利用能量相关搜索法对回波信号进行分析和计算，得出超声波实时照射下的海底表面微地形高程数据，为海底采矿车智能化开采提供实时、快速的最佳切削深度参数。
The results show that ( 1 ) the " prediction & cancellation " method can successfully smooth the reverberation and sharpen edges of the echo , so may detect echoes which power are great than the reverberation background by odb in one channel , ( 2 ) the scaled probabilities method can effectually separate a echo which power is great than the background by 6db , while the reverberation is cancelled dr astically 果。计算结果表明， “预测一抵消”算法对混响有平滑作用，对回波则有突出信号边缘的作用，单通道情况下的最小可检测信号干扰背景功率比约为odb 。概率净化算法在信号干扰背景功率比大于6db的情况下能有效分离回波、抑制混响。
During designing hardware circuit , we have used the supreme limitation to raise driving - ability and raise the distance of measurement to returning ware by taking some measurements just like multi - polar enlarging , according to the ultrasonic characteristic of index attenuation when it ' s spreading because we need to measure longer distance ( from several meters to dozens of meters ) 在硬件电路的设计中，由于需要测的距离较长(几米到十几米) ，针对超声波振幅在传播时呈指数衰减的特性，最大限度地提高驱动能力，对回波进行多级放大，达到了设计要求。
At last , this paper analyzed the influence of the inversive receiver to the chracteristic of the clutter and the ratio of signal power and the noise power , discussed the effective detection of target signal in correlated clutter , and then put forward a new method naming multi - periods shift accumulation for detecting moving target when not knowing the exact movement parameter 最后，本文分析了倒置接收对目标回波信噪比及杂波特性的影响，讨论了在相关杂波区对回波信号有效检测的方法。针对如何在弹目相对运动参数未知的条件下对高速运动目标进行积累检测这一问题，提出了一种多周期移位积累的新方法。
In recent years , the worldwide researchers pay much attention to fourier telescopy . it is an active imaging technique that encodes the information in the temporal instead of spatial domain , then receives the speckle and deposed of it to reconstruction the object image . now , the high - resolution technique is under the condition of deeply researched 它是一种主动式干涉成像技术,这一技术通过时域内的相位的调制完成直线条纹对目标的扫描,从而达到对深空目标频谱的抽样,然后接收其散射回波,对回波信号进行处理,进而还原出目标的像。
From the result we get the following conclusion : for narrow - band signal , the effect of the method based on fft is best . for wide - band signal , when snr is up to certain degree ( higher than - 7db or so ) , the curves of square error of modified methods are more obvious and closer to crb . for an echo composed of more than one frequency or direction , space - frequency distribution could show more direct information of frequency and direction , which is more advantaged to make precise judge and estimation for doa of echo 从估计结果发现，对于窄带回波信号，基于fft的方法估计性能大大优于其他方法；对于宽带回波信号，在信噪比达到一定程度(高于约- 7db )时，补偿后的几种估计法的性能改善均比较明显，误差曲线越来越接近crb曲线；对于回波中存在多频率多方位的情况，空间?频率分布图能提供较为直观的频率及方位信息，因此应用空间?频率估计法来进行方位估计，更有利于进一步对回波的具体方位进行准确判断和估计。
A new fluid level measurement method , based on ultrasonic measurement , for calculating the velocity of sound and the fluid level is presented . this method points out that a low - power acoustic signal generator under control can be used to emit spread spectrum signals and the fluid level can be worked out by detecting the correlation - peak output of the matching filter whose input is the echo signal received by a microphone 本文提出了一种新的基于扩频通信原理的液位测量方法，使用可控声源，发射较低功率的频谱扩展信号，在接收端对回波信号进行匹配滤波处理，通过检测相关峰来确定特征回波的位置，从而计算出液位。
Through analyzing the spinning echo , the arithmetic of " estimation of signal with polynomial phase " is adopted to estimate parameter of echo ' s phase . then the influence of high step phase pro duced by spin is removed . the one - dimension range - profile can be renewed by this arithmetic and the good effect is showed by the result of simulation in chapter v , the main works of this dissertation are summarized and the future researched areas are pointed out 通过对自旋目标回波的分析，本章采用了“多项式相位信号系数估计”算法对回波相位进行参数估计，可以去掉旋转产生的相位高次项影响，从而恢复给出目标的一维距离像，仿真实验表明本算法取得了好的效果。
The main content and work in this dissertation can be summarized as follows : 1 . this dissertation introduces the principles and working mode of x band gbr simulation system , mainly analyzes the function of rg and sp sub - systems . a total design of rg and sp simulation sub - systems is presented according to the system requirements 本文的主要内容和工作如下: 1 .介绍了x波段地基雷达仿真系统的工作原理和方式,着重分析了回波生成和信号处理子系统在整个仿真系统中的功能,根据系统参数对回波生成和信号处理仿真子系统进行了总体设计。
