Noiseimmunity of the search for broadband frequency manipulation signals with minimal shift of the radio navigation system under the influence of structural interference

In the presented work, an assessment of the noise immunity of the parallel algorithm of the broadband signals with frequency manipulation with minimal shift time search is given. The threshold value of the Signal-to-Noise ratio per one L signal is used as a criterion, which ensures the required accuracy of code synchronization with a given error probability. In this case, the task of temporary search is formed as a task of recognition L signals whose modulating code sequences { dkl } differ by a time cyclic shift τ k = ( k - 1) τ э ( k = 1, L , L - the length of the modulating code sequence, tэ - the duration of the signal element or the element of the modulating code sequence) equal to energy. The L-dimensional probability density of the modules V 1,..., VL (Vi - the correlation module of the analyzed and comparison signals at the output of the quadrature correlator) is preliminarily determined. The probability of error is determined by L-multiple integration of the L-dimensional probability density of modules V 1,..., VL . The problem of determining the energy losses in the analyzed signal under the influence of structural interference is solved. In this case, a quadrature recognition circuit of one of two discrete signals is used and the Signal-to-Noise ratio at the output of the recognition circuit is determined, taking into account the effect of structural interference, and a comparison is made with the Signal-to-Noise ratio for the analyzed signal acting at the input of the quadrature recognition circuit. An assessment of the impact of structural interference on the temporary search is given, taking into account the normalized periodic autocorrelation function (NPACF) of the analyzed signal and structural interference (at L = 16383). It is shown that it is most rational to work with NPACF in its ascending section (cycle interval [ 361τ э ,540τ э ]), while the reciprocal correlation coefficient will not exceed 4 · 10-3 and the equivalent energy losses of the analyzed signal will not exceed 3 dB. At an intensity of 34 dB of structural interference, the use of an ascending section of the NPACF allows minimizing the energy losses of the analyzed signal and temporary searching for a time of 0.35 s (at τ э = 2.5 microseconds).