V.N. Bondarenko, V.F. Garifullin, R.G. Galeev, T.V. Krasnov

In the article there is a quasi-optimal algorithm for finding the spread spectrum signal (SSS) with minimal frequency shift keying due to delay time. There is a structure of quasi-optimal correlation receiver that implements the proposed searching algorithm. Quadrature converter generates the observation by multiplying the counts adopted in the implementation per the quadrature reference signals of the carrier frequency. In device of step-by-step processing the equal correlation processing observation algorithm is realized at intervals which are equal to the element length of SSS. The results of step-by-step processing stored in operational memory device and they are used for calculating the quadrature components and the cross-correlation function module in each channel of the searching block. The solver of searching block determines the channel number with a maximum output value (correlation module), forming the estimate of delay time. The noise-immunity analysis of proposed searching algorithm with using the anomalous errors as a criterion for the probability which exceed the value equal to the element half-length of SSS is performed. The formulas for probability errors in the two extreme cases are obtained: when the synchronization error is equal to zero (the most favorable case), and when the error is equal to the element half-length of SSS (the worst case). The analysis results with using the calculation formulas and statistical modeling of considered algorithm are shown. The loss in noise-immunity of quasi-optimal searching algorithm in comparison with the optimal searching algorithm is less than 1 dB and it is entirely repaid by the benefits of practical implementation.