Passive Detection Positioning Technology

With the rapid development of science, radar electronic war has come to a new phase that challenged by four main threatens: E- interference, anti-radiation missiles, low-altitude protruding and stealthy weapons. The conventional active radar can hardly survive under such circumstance, let alone to fulfill its mission. The passive detection system is one of the various solutions put forward to tackle this problem. Because this system gives no radiation wave itself and works completely in passive mode, multi-station passive detection system has attracted more and more attention in a variety of country.The passive positioning system gives no radiation wave itself but receives passively the electromagnetic signals (include visible rays and infrared signal) radiated from other source and pin points its location as well as its moving state by measuring the parameters, this feature of staying in concealment provides a fantastic improvement in its survival ability under E-war environment. The passive positioning tracking system can classified according to its components into two types: multi-station system and single-station system. As the traditional multi-station system requires not only the sub-stations to operate synchronously and transmit a great amount of data among them, but to blend the collected data, this led to an increased system complexity and dependence on each other as well as low flexibility. While the single-station system has no such disadvantages, it performs with high flexibility its tasks completely by itself. From the positioning principle of the conventional radar, a single passive detector couldn't find the specific location of a radiation source; therefore it's impossible to use such a detector to determine the source position. But if we could construct a geometric relationship between the location change of the source and the detector, we can estimate the source's position and motion state from data gained by sequentially measuring the target signals as their positions change when they are moving.The external radiating operation frequency, being utilized by the passive detection and the positioning system, is being towards the development of under 1GHz which is the exact frequency utilized by the ground broadcast station,FM radio station,TV and mobile communication. As they are distributed almost in every corner of the globe, the passive detection and the positioning system gain a very broad and practical application, in addition, the absorbability of the electromagnetic wave absorbing material on this frequency is not good, and the shape size of the hiding target is approximate to the operation wave length, which leads to generate the electromagnetic resonance, it implies that the hiding performance of the aircraft deteriorates seriously. If, on this frequency, the hiding aircraft is detected, the active radar will be interfered by the signals from the broadcast station,TV and communication stations, but the passive radar will not.The positioning method of the passive detection radar has been stated in detail in the thesis, taking the land-based passive detection positioning as example. Some deep research on the cross positioning of the passive direction-finding and related technology have been done. The assumption of establishment the army air defense net is put out combined the author's actual work. The assumption has the significance, both the theory and reality for developing our country's passive positioning technology and sharpening the abilities of our army's early warning detection, defense and counterattack, etc, under the condition of complex electromagnetic environment.The computer simulated tests for all kinds of cases have been completed. The validity of various tracking computation has been verified.