Study Links Satellite Downlink Interference Technology And Its Implementation

With the development of technique, the satellites are widely used in civil and military areas. The data link between the satellite and the ground center is crucial in the process of the information acquisition. For those reasons, the research for jamming the satellite downlink is very important. Jamming can obstruct the transmission of information, or reduce the effectiveness of the transmission. Especially in wartime, jamming can decrease the reconnaissance and the intelligence information utility from the satellite of hostile country.This dissertation presents the operational principle of the downlink system of satellite communication and the telemetry system, and the mode of modulation and demodulation of the link. Because the satellite downlink operates under the limitation of frequency and power, PSK modulation is the first choice. The thesis thesis mainly analyses the modulation based on Gray code and the demodulation of coherent and incoherent.Reconnaissance is the base of the jamming. The thesis analyses some problems in the engineering of the reconnaissance system, include the covered frequency range, the sensitivity of the system, the measures of intercepting signals, and proposes the methods of estimation of the carrier and the symbol rate.The jamming methods of the satellite downlink for data transfer and telemetry are studied detailed in the thesis. The dissertation analyzes the possibility of jamming the satellite downlink, proposes the effective way to jam the satellite downlink by using the high altitude platform, and analyses the requisite effective isotropic radiated power (EIRP) of jamming. Based on analysis, the thesis proposes the method for jamming the synchronization system of the downlink and the signal with the modulated information. Two kinds of jamming modes, pseudorandom code noise modulation and pulse modulation that similar to satellite signal modulation, are discussed and the corresponding problems to be considered in engineering are defined. Many simulation experiments have been accomplished through which the effectiveness of jamming modes, the Bit Error Rate (BER) performance, and the Jam-to-Signal-Ratio (JSR) requirement of each jamming mode is validated. The factors decreasing the jamming effectiveness are analyzed quantitatively.The experimental prototype has been constructed and is described briefly in the thesis. The digital jamming source and the platform of steadying the antenna direction are introduced in detail. Some jamming experiments have been accomplished using this system. According to the experimental results, the jamming effectiveness is analyzed and evaluated.