Uav Data Link Control Key Techniques Of Frequency Hopping Time And Frequency Synchronization

Since World War II, the enthusiasm to military weapons is growing in all thecountries. Certainly, the achievements are fruitfully. A variety of new weapons havebeen came out. Particularly, unmanned aerial vehicle (UAV), which is known as the“clairvoyance” and “killer” of the modern battlefield, has been developed rapidly.Nowadays, it has been widely used for all sorts of military tasks, such as reconnaissanceand surveillance, ground attack, targeting, electronic interference, effective assessmentof attack damage, communications relay, etc.Data link technology is mostly used in the UAV systems for wirelesscommunication. In secret communication, it is usually combined with frequencyhopping(FH) technology to achieve good performance of anti-jamming andanti-intercept. How to realize the accurate frequency-hopping synchronization is one ofthe key technologies in FH systems.Thus, the synchronization of time and frequency, which is the key technology of FHin control data link system of UAV, has been studied in this thesis. A FHsynchronization strategy as well as a synchronization algorithm of time and frequencyhas been given for one-station-one-UAV communication mode. Meanwhile, aquasi-synchronous networking solution has been proposed for one-station-multi-UAVcommunication mode. Besides, the feasibility of synchronization algorithm andquasi-synchronous networking solution have been analyzed by MATLAB simulation,which provides a theoretical basis for the project realization.First, the FH synchronization is studied in an air-ground communication ofone-station-one-UAV scenario. The physical layer frame format, FH pattern, FHsynchronization strategies and processes have been designed. Meanwhile, The coarsesynchronization and accurate synchronization algorithms in FH system have been given,analyzed by MATLAB simulation. With signal to noise ratio (SNR)13dB, which is theworst case to work following the target, the correct detection probability reaches99.06; false alarm probability is0.63; root mean square error of the residualfrequency offset is286.4Hz with the frequency offset range of [65.2kHz,62.5kHz).Second, we propose a FH networking solution for one-station-multi-UAVcommunication. This solution combines frequency division with code division, usesquasi-synchronous method. With several users in the same network, compared to primesasynchronous networking, simulation results reveal that the performace of multipleaccess interference and synchronization is better by using quasi-synchronousnetworking. Adopting quasi-synchronous networking, the bit error rate (BER) is quiteclose to the theoretical curve of BPSK; and the performace of coarse synchronization isthe same as single user. However, adapting primes asynchronous networking, there isserious multiple access interference, and the synchronization performance is poor.The method of one-station-one-UAV FH synchronization, which is given in this thesis, is applied to air-ground data link communications. It is already realized in theengineering applications. The one-station-multi-UAV FH networking solutions providesa theoretical analysis for the system of ground control station real-time manipulatemultiple UAVs.