Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2017, Vol. 14, No. 1, pp. 71-79
Method of reducing transmission time of high-resolution digital images from unmanned aerial vehicles
E.P. Petrov
1 , N.L. Kharina
1 , E.D. Rzhanikova
1 1 Vyatka State University, Kirov, Russia
Accepted: 13.01.2017
DOI: 10.21046/2070-7401-2017-14-1-71-79
Large amount of information in remote sensing systems is transferred with mini or micro unmanned aerial vehicles with limited energy resources. One of the main requirements is the distortionless transmission of high-resolution multi-bit digital images (MDI) in a real time scale. The use of well-known MDI compression methods requiring large amount of computation on board the aircraft is virtually impossible due to the limited energy resources. In this paper the transmission of MDIs by multiposition phase-shift keyed (MPSK) signals is proposed. Its disadvantage is a decrease of receiving noise immunity by 3 dB at each division of a phase of MPSK signals in two. A method of compensation of noise immunity losses of MPSK signals receiving is proposed. This method is based on effective utilizing of statistical redundancy caused by MDI pixels correlation. The research has shown that the use of quadrature phase-shift keyed (QSPK) signals reduces the MDI transmission time twice without the noise immunity losses compared to BPSK signals. The use of 8-PSK signals allows to reduce the MDI transmission time by three times and to compensate for the noise stability losses almost completely. The application of higher-order PSK signals to reduce the MDI transmission time is inadvisable due to the impossibility of the compensation of noise immunity losses because of limited amount of statistical redundancy in MDIs. The greatest compensation of noise stability losses due to application of MPSK signals is reached at low signal-to-noise ratio less than -3dB at the input of radio receiver.
Keywords: mathematical models of digital images, mini unmanned aerial vehicle, multi-bit digital image, the Markov chain with multiple states, the algorithm of two-dimensional nonlinear filtering, multiposition phase-shift keyed signals
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