No abstract

The basic directions of unmanned aircraft systems applications in the civil field has been reviewed, the concepts of creation and organization of civil unmanned aircraft systems has been considered depending on the task orientation as well as the wide range of issues concerning the use of existing capacity for the design, manufacture and operation, with subsequent integration into the common air space.

The peculiarities of correlation-extreme visual navigation are considered. Descriptors with 64 elements of feature points of surface images are selected on the basis of the speed-up robust feature method. An analysis of possible criteria correlation functions is carried out to find the best match between the template descriptors and current images. The use of normalized correlation function is proposed based on the matrix multiplication properties of descriptors. It allows minimizing the number of false matches in comparison with the Euclidean distance in the descriptor space. The proposed matching strategy sufficiently decreases the computation time.

For modelling transmission of ADS-B messages via low-orbit satellite constellation Iridium, the original model of a communication channel “Aircraft-to-Satellite-to-Ground Station” was built using MATLAB Simulink. The model comprises “Aircraft Uplink Transmitter” (Bernoulli Random Binary Generator, Convolutional Encoder, BPSK Baseband Modulator, High Power Amplifier with a memoryless nonlinearity, Transmitter Dish Antenna Gain), “Uplink Path” (Free Space Path Loss, Phase/Frequency Offset), “Satellite Transponder” (Receiver Dish Antenna Gain, Satellite Receiver System Temperature, Complex Baseband Amplifier, Phase Noise, Transmitter Dish Antenna Gain), “Downlink Path” (Free Space Path Loss, Phase/Frequency Offset), “Ground Station Downlink Receiver” (Receiver Dish Antenna Gain, Ground Receiver System Temperature, Viterbi Decoder), “Error Rate Calculation” block and “Display”. The modelling was realized without and with convolutional coding (r = 3/4, K = 7) at different noise temperatures and free space losses. Dependencies of a Bit Error Rate on free space path losses, antenna's diameter, phase/frequency off-sets, satellite transponder linear gain, aircraft and satellite transponder high power amplifier back-off level, and phase noise were received and analysed.

Global technologies of data transmission in real time are developing constantly. Therefore, modelling of messages transmission through satellite constellations is an actual problem. In this paper the original model of a communication channel ‘Vehicle-to-Satellite-to-Ground Station’ based on principles of the IEEE 802.11a standard is designed using MatLab Sіmulіnk software. The model allows simulating data transmission with data rate from 6 to 54 Mbit/s using adaptive modulation. Two types of channels were analysed for uplink/downlink modulation – a free space path losses with phase/frequency offset and Additive White Gaussian Noise (AWGN) link. On the base of this model, channel integrity was investigated and dependences of a Signal-Noise Ratio (SNR) on free space path losses, antennas diameters, number of OFDM symbols and satellite transponder noise temperature were received.