The Best Jamming Study On Carrier Synchronization Module Of Communication System

Communication technology is widely equipped in military electronic devices, theeffectiveness of communication electronic equipments is essential to the security ofone’s combatants and property, and may even lead to the final result of the war. It issignificant to conduct communication countermeasure and research on the best jammingmethod of the communication systems.In the thesis, the deficiency of BER-based communication jamming effectivenessevaluation method at present is analyzed, which assumes the communication system isin precise locking of the carrier in advance, and adopts multiple hypothesis testingstatistical methods to analyze the BER. While in practical application, when the lockingof the carrier is failed, the statistical BER is meaningless, and the method becomesinvalid. The carrier synchronization module plays a very important role in thecommunication system, and it is a prerequisite for the subsequent transmissioninformation received correctly demodulated. By conducting the effective jamming ofthe carrier synchronization module of communication system, twice the result with halfthe effort can be achieved. Nowadays, the study of phase-lock loops is mainly theimprovement of hardware circuits, while the software analysis and the performance injamming circumstances is less discussed. This thesis focuses on the best jammingmethod of the phase-locked loop in communication system, and mainly contains the twoaspects as follow:Firstly, taking the widely used BPSK communication system as an example, thetypical Costas loop is mathematically modeled, the original carrier lock determinationalgorithm is being improved to be convenient with later computer simulation, theperformance of Costas loop in jamming circumstance is analyzed, the optimal phasedifference sequence of the jamming and transmission signal is theoretically researched,finally the qualification of the optimal jamming signal is proposed. The qualification isas follow,(a) the jamming signal symbol must be identical to the transmission signalsymbol,(b) the phase difference sequence of the jamming and transmission signal mustbe the optimal phase difference sequence,(c) under the premise that jamming signal can pass the loop filter, the jamming signal carrier frequency and transmission signal carrierfrequency differences should be as large as possible, that’s to say the jamming signalcarrier frequency should be as close to the edge of PLL filter.Secondly, the optimal jamming to the carrier synchronized communication systemis deeply analyzed, and the optimal jamming signal is the signal has a pulse durationratio changed with the JSR input, and the computer simulation has been conductedunder the power criterion. Then based on the probability criterion the optimal jammingsignal of the Costas loop is confirmed through computer simulation. By comparing thetwo jamming method, the optimal jamming of Costas loop is the best suppressingjamming signal of the communication system. Finally, comparing the jamming resultsof the best suppressing jamming signal with the deceiving jamming signal, theconclusion of the optimal jamming of the phase-lock loop is the best jamming of thecommunication system is drawn.