Search for broadband signals ground-based radio navigation system

In the present paper, a method of temporary search for broadband of frequency manipulationwith minimal shift keying (MSK) signals of ground-based radio navigation systems (RNS) is considered. The method is based on a multi-alternative optimal signal detection (the signal may belong to one of the orthogonal signals) using the evaluation-correlation principle of processing (ECPP) under conditions of a priori uncertainty. The problem of representing broadband MSK signal as a signal with double discrete frequency-phase modulation (FPM) was solved. The law of phase manipulation in the form of a binary sequence of elements bl of a length code L τ э (in the “Sprut” RNS , L = 16383 , t э = 2.5 mcs - is the duration of the signal element) is defined through the law of frequency manipulation in the form of a binary sequence of elements dl of a known length L code. The representation of the signal in the form FPM allows, during correlation processing, to replace the correlation integral on the interval [0, L τ э ] by L the sum of correlation integrals on the intervals [0, τ э ] or by L the sum of element-by-element correlations. The calculation of element-by-element correlations allows the use of a matrix apparatus for the ECPP of the analyzed signal. With the technical implementation of the “search” procedure, there is no need to form 2 L pairs of reference quadrature signals with the length L of the modulating code, and instead of that a pair of element-by-element correlations is memorized and over time τ э , according to a code element dlk , cyclically shifted by k -1 elements, frequency manipulation and a code element bkl , cyclically shifted by k -1 elements, phase manipulation, block-by-block accumulation L of quadrature correlations is performed. The use of upper-left and lower-right triangular matrices with binary elements bkl makes it possible to search for broadband MSK signal with additional phase manipulation of a discrete information message. The structure of the optimal algorithm of parallel search for ECPP of the broadband MSK signal with the use of a matrix apparatus, which allows to implement the optimal algorithm “of search” during the duration L τ э of the signal in real time.