Yu.E. Korchagin – Dr.Sc. (Phys.-Math.), Associate Professor, Voronezh State University
К.D. Titov – Engineer, MTSC Air Forces «MAA named professor N.E. Zhukovsky and Y.A. Gagarin» (Voronezh)
The task of the detection signal observed against the background of noise is relevant for many practical applications in theory of con-nection, location, navigation and manipulation have been described in literature. The radiosignal is narrowband has been assumed. However, communication system development requires increase in the volume and the speed of data packets transfer, and radiolocation system development also requires space review speed growth and the growth of energy potential of radiotechnical complexes. Operative frequency band expansion can be realized by creating ultra-wideband systems of connection and location. In such systems it is often required to detection a radiosignal for which the conditions of narrowbandness are not accomplished. Such radiosignal is called ultra-wideband quasi-radiosignal (UWB-QRS).
As is often unknown duration of the received signal, in other works investigated quasi-likelihood (QL) algorithm detecting UWB-QRS with unknown amplitude, duration and initial phase. However, the QL detector has a more complex structure than the quadrature
detector narrowband signal. Therefore, it may be advantageous to use more simple quadrature detector UWB-QRS. In this paper we investigated the quadrature QL algorithm detecting UWB-QRS, which is called quasi-optimal (QO). The UWB-QRS at the input QO
detector has a random shape, unknown amplitude, duration and initial phase, and observed with Gaussian white noise has been
As determinative statistics for the synthesized detection algorithm used functional logarithm likelihood ratio.
When used QO detection algorithm the UWB-QRS with unknown parameters comes to the input of narrowband radiosignal detector. The main difference between the QL and QO algorithms with each other is a neglect of step synthesis integrals of functions oscillating at twice frequency. QO detection algorithm analysis was performed. Only noise comes when there is no input signal QO detector. If there are a UWB-QRS received realization, integrals of functions oscillating at twice frequency, included in quadrature, can not be neglected. It was an expressions probability of false alarm and veprobability skip signal for QO detector.
The presence of expression for the probability of error of the synthesized algorithms can performed a comparative analysis QL and QO detection algorithms. For example we consideration detection UWB-QRS with rectangular modulating function. It is shown that the difference between the expected duration of its true value leads to a loss in efficiency detection of both QL and QO algorithms. At the same duration deviation QL algorithm has a best detection efficiency in comparison to the QO algorithm.
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