A Study Of Multi-Satellite Passive Location System Based On TDOA

With the rapid development of electronic technology, the supports of the electronic technology and devices have been indispensable parts for the modern military activities. Seizing the initiative of electromagnetic waves is equivalent toseizing the initiative of the whole situation. Electronic reconnaissance satellite has become an effective means for obtaining information with its excellent properties such as long detection range, high sensitivity, strong mobility, wide detection frequency range and its orbit being no restriction of the boundry and terrain.Passive location technology is the basis of electronic reconnaissance satellite. The location of target radiation sources are indicated through passively acquiring the electromagnetic waves radiated, scattered or reflected by the target radiation sources. Without radiating any electromagnetic waves itself, passive location can achieve high imperceptibility which has important significance to the development of electronic countermeasures.Based on the different ways of location, passive location can be classified by cross location, Time Difference of Arrival location(TDOA), Frequency Difference of Arrival location, Phase Difference of Arrival location and hybrid location. Among them, the TDOA location is the most widely used method for its fast speed and high precision.TDOA location is also known as hyperbola location. The target location is determined by the time lag of target signals arrived at different observatories. TDOA location can be divided into four parts:(1) Selection and pairing of the target signal, (2) Estimation of the time lag arriving at different observatories, (3) Acquiring the target location by special algorithm, (4) Analysis of the location error. The TDOA location is studied systematically in this paper. The pulse pairing, time parameter estimation, location algorithm and error are introduced, simulated and analyzed. The contents are as follows:Chapter I:The background and significance of the research is analyzed. The passive location technology is introduced. The development actuality and orientation of electronic reconnaissance satellite are presented.Chapter II:First, the high repetition frequency pulse pairingambiguous problem and the corresponding solution is introduced. The high reprtition frequency pulse pairing method based on the mutual measurement equality is simulated, and the reliability of the algorithm is verified. Then the two methods of TDOA estimation, one based on the signal synchronization and the other based on the time synchronization, are explained. Several estimation algorithms of TDOA of the two methods are presented respectively. The algorithms of generalized cross-correlation and third-order cumulant based on the signal synchronization are simulated, compared and verified.Chapter III:The principle of TDOA location is presented. The geometry location principle and target solution of two-dimensional and three-dimensional are introduced. The coordinate formula for transforming between space coordinate and geodetic coordinate is provided. The precision of the TDOA location is analyzed and the corresponding simulation is given. The location precision at different observatory, baseline distance, and irregular geometry center are analyzed.Chapter IV:The linear and nonlinear algorithm of TDOA location algorithm are presented. The ML and NLS algorithm of nonlinear algorithm are simulated and compared. The location properties of the two algorithms are verified by the observation of the root mean square error, the Cramer-Rao Lower Bounds and anti-interference ability of error.