OPTIMIZATION OF SIGNALS TRANSMITTED IN NARROWBAND COMMUNICATION CHANNELS TO OBTAIN MAXIMUM RESPONSE AT THE CHANNEL OUTPUT

Galina Cherneva; Hristina Spiridonova

Scientific paper ID 2043 : 2020/3

OPTIMIZATION OF SIGNALS TRANSMITTED IN NARROWBAND COMMUNICATION CHANNELS TO OBTAIN MAXIMUM RESPONSE AT THE CHANNEL OUTPUT

Galina Cherneva, Hristina Spiridonova

Various methods are used to improve the resistance to interference in the transmission of signals in radio communication systems. In general, they can be divided into two types: methods related to the optimization of signal processing at reception and methods for optimizing the signal shape in the transmitter.

In the present work the problem for optimization of a signal transmitted on a narrowband communication channel is set and solved, so that the maximum value of the signal is observed at the output of the channel. The optimization problem is solved with the methods of functional analysis. A functional is defined, which determines the condition that the transmitted signal is maximum at the time of reception. The functionality describes the quality criteria by which the d signals are synthesized.

According to the theory of variational calculus, the extremum conditions of the synthesized functional are applied. By analogy with the problems for the extremum of a function, the extremum of the functional exists under certain necessary and sufficient conditions. In order for the functionality to have a maximum, its first variation must be zero and the second must be negative. This leads to the compilation of a system of integral-differential equations, the solution of which are the d signals.

Thus, the analytical expression for the form of the transmitted signal, which satisfies the optimization indicators, is derived.

The problem is considered and solved in the case of a telephone channel for connection with a cutoff frequency of 3400Hz and attenuation 3dB. The communication channel is approximated by an eighth-order Butterworth low-pass filter.

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оптимизация на формата на сигнала функционал теснолентов комуникационен каналsignal format optimization functionality narrowband communication channelGalina Cherneva Hristina Spiridonova

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