Target Localization And Site Error Calibration In Multisite Radar System

With the development of modern technology, electronic warfare has already become the main battlefield of modern war. As radar is a main factor of electronic warfare, the grasp of the highest radar technology is the key to win. By radar, we can detect scouting planes and attack weapons from the enemy?s side, after which tracking and attacking can be done to prevent us from potential danger. However, all this is based on the precise locating of the threat target. So, numerous researchers have made much contribution on the enhancement of radars? positioning accuracy.Generally speaking, there are two types of methods for radarpositioning, the active positioning and the passive positioning. Active positioning is a traditional one, by which radars have to actively emit electromagnetic waves, and the locating task can be completed through the analysis of the target echo. It is because this characteristic that the radar has to emit electromagnetic waves that makes active radar easy to be detected by enemy, thus under threaten. Once the “eye” of the war is destroyed, everything bad can happen. What?s more, the application of stealth airplane makes it impossible for active radar to locate. Under this circumstance, the passive radar emerges. Due to its passive way of working, passive radar can detect the enemy without being anti-detected, thus leading to its wide application in national defense. Passive location technology has made great progress since more and more countries put emphasis on it. Introduction of the two positioning types is made, so are several basic methods which belong to the two types respectively. Besides, the positioning accuracy of each mentioned method is analyzed; the factors that affect the positioning accuracy is also analyzed and simulated. As to active positioning methods, the Distance Measurement algorithm is described in detail. This algorithm, a method wildly used for its high positioning precision, uses the distance information to locate targets. However, at least three sites should be used in this method. There are other active positioning methods which use information more than distance, such as, angle information. As to passive positioning, the classic TDOA method is introduced. The time difference of arrival is applied in this method to locate targets. By detailed analysis and simulation, the factors that affect the positioning precision is concluded, which include the sites error, the TOA error, the layout of stations, the height of target and the distance between the main site and assistant sites. An optimization scheme is deduced to overcome the drawback in the traditional TDOA method that the locating precision of low-altitude target is quite disappointing. The optimization uses an additional information of the main site?spitch angle.For the reason that the site error makes great difference in radar positioning, many scholars make studies on site error calibration. This paper emphasizes on site error calibration. The method which uses laser to get the high-precise distance information between every two sites to correct the site error and the method which suppose the location of the target is given accurately are mentioned.