Abstract:

A novel uplink data transmission scheme based on cycleorthogonal M-ary spectrum spreading was proposed for unmanned aerial vehicles (UAVs). According to this scheme, potential periodicity in the transmiting signal is eliminated and the data is hard to detect or intercept with conventional technologies, thus the anti-jamming and anti-intercepting capabilities of the system can be achieved. In the dynamic circumstance, the great move speed and acceleration of the carrier results in drastic variation in carrier wave Doppler frequency shifts, which makes the tracking loop of general receivers out of balance. A FPLL tracking scheme based on lookup tables(LUT) was proposed, which adopts a list of empirical values in FLL and the bandwidth of the loop filter in FLL can be adjusted adaptively. As a result, a more precise tracking can be attained at any time.

Key words: communication technology, unmanned aerial vehicle(UAV), cycle-orthogonal M-ary spread spectrum, carrier tracking