A.A. Monakov

Saint-Petersburg State University of Aerospace Instrumentation (St. Petersburg, Russia)

Signal spreading is a phenomenon caused by the multipath propagation of a signal in propagation media or by the spatial extend of a target under the radar surveillance. Received signal can be spread over the time delay (the range-spread signal), the frequency (the Doppler-spread signal) and the angle (angular-spread signal). It is possible to represent the spread signal as an interference of signals transmitted or scattered by a number of point sources with particular complex envelops and values of the measured parameters (time delay, frequency, direction-of-arrival). Detection of the signal spreading in a propagation channel over its measured parameters is an important task, since it allows to choose the optimal set of signal processing algorithms. The solution of this problem requires the use of adaptive methods due to the existence of a priori uncertainty about unknown parameters of the received signal: the measured parameters and the mean powers of partial signal sources, the combined performance of which produces the spreading effect. The proposed article discusses an adaptive detection algorithm of the signal spreading. It is shown that the problem can be treated as a binary hypothesis test: the null hypothesis H0 corresponds to the point signal source and the alternative hypothesis H1 to the spread signal source. The test statistics is based on the Kullback - Leibler distance, as a measure of difference between two probability distributions. It is supposed that the received signal is Gaussian distributed with unknown correlation matrices. For the null hypothesis H0 the unknown parameters, which are the mean signal power and the source coordinate, are estimated by the maximum likelihood method. Using these estimates the signal correlation matrix is constructed. For the alternative hypothesis H1 the sample correlation matrix is used. The proposed algorithm is verified via computer simulation. The simulation of the proposed algorithm confirms its performance: for the number of receiving channels M = 16, the number of signal samples N = 128, and the signal relative extend b = 0.1, the threshold signal is q2 = 14,3 dB for the detection probability D = 0.9 and the false alarm rate F=10-2. Further investigations will be directed in derivation of the probability distribution of the test statistics.

Monakov A.A. Detection of signal spreading in propagation channel. Science Intensive Technologies. 2021. V. 22. № 8. P. 34−40. DOI: https://doi.org/10.18127/j19998465-202108-06 (in Russian)

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