Finding Algorithm Based On The Ads Satellite Reconnaissance Link In Modeling And Interferometer

A research on the performance of reconnaissance satellite is done in this thesis aiming to provide technical support for related demonstration work. In this thesis, not only the model and simulation of the whole satellite reconnaissance link is set up based on ADS platform, but also the direct-finding work is done. The main job is as follows:1. The model of the whole reconnaissance link is established according to the actual electromagnetic environment of reconnaissance satellite in this thesis, and the surveillance and interception performance of satellite are analyzed as well.The whole reconnaissance link is established in this thesis, which are: the typical military satellite's ground station, the interspaced transmitting link, the satellite antenna array and the surveillance receiver. All of the models are based on the actual electromagnetic environment and system parameters which can be modified according to actual needs. Moreover, the performance of receiver is evaluated using proper simulators with certain parameters. What's more, the interception performance of reconnaissance satellite is analyzed as well.2. The direction-finding flow and the positioning principle of space borne digital interferometer are analyzed in this thesis. And what's more, the formula for calculating the latitude and longitude of the ground target is deduced on the basis of existing theory.To realize the reconnaissance, a direction-finding algorithm should be used to deal with the output of the antenna model. The interferometer direction-finding algorithm is used because of its mature theory and high accuracy. Considering that the direction-finding algorithm deals only with the output of ideal antenna and there is an existence of amplitude-phase errors in real array channels, therefore, signal's channel errors must be corrected before using direction finding method. The introduction of direction-finding flow of interferometer system is put forward in this thesis, which can be divided into three parts: the pre-processing before channel error correction, error correction algorithms and the direction-finding principle of five-element L-array digital interferometer. In addition, the formula for calculating the latitude and longitude of the ground radiation source is deduced using estimated incoming orientation on basis of its physical meaning in this thesis.3. The direction of signals from antenna model in ADS is found in the thesis.In this thesis, the respective advantages and disadvantages of the four error correction algorithms are discussed by means of simulating their effects on positioning accuracy in different parameter groups. And at last, the least-squares calibration algorithm which is an active method is chosen as the follow-up treatment measure. In order to get the assistant signal source, a new frequency measurement algorithm is used to estimate the frequency of the incoming wave. The principle of the new algorithm is to constitute frequency revising term by use of the real part of signal's DFT transforming coefficients. After that, the least-squares calibration method and the l-shape digital interferometer direction-finding algorithm using long baseline matched with short one are combined together to estimate the location of radiation source in ADS model , and the positioning accuracy is calculated as well.