MODEL PARAMETER IDENTIFICATION OF ACOUSTIC SIGNALS IN AUDIO EXCHANGE TELECOMMUNICATION SYSTEMS UNDER CONDITIONS OF INTERFERENCE AND ACOUSTIC FEEDBACK SYSTEM

The paper reports the solution description for the problem of designing the models of the systems of information exchange with the acoustic feedback with the use of the methods of the linear functional-differential equation theory. With the aid of them it is ensured a stability increase in systems of operational-command loud-speaker communication and notice, and also the problem of echo decrease at the inputs of speech transforming devices is solved that conditions on quality increase of their functioning. In the paper there are presented models having a continuous consequence and taking into account a character of acoustic echo-signals in closed spaces more complete which results in authenticity increase of modeling results at echo-signal compensation. To solve the echo identification problem the functions of echo lag distribution are approximated by a number of exponents which simplifies the equations and allows accepting a consequence both at a finite and infinite interval. The investigation of the stability of models of systems with the acoustic feedback in the paper is carried out by a frequency method. At that there is considered an approach to the estimate of correlate and spectral functions of acoustic signals which is based on a parametric presentation of acoustic signals and components of noise constituents

Regularly Varying Solutions of Half-Linear Diffferential Equations with Retarded and Advanced Arguments

Sharp conditions are established for the existence of slowly varying solution and regularly varying solution of index 1 of the half-linear functional differential equation with both retarded and advanced arguments of the form (|x′(t)|

Continuous Dependence of Fixed Points on Parameters and Initial Conditions

The main purpose of the paper is to establish conditions for a continuous dependence of fixed points and an application to non-linear functional differential equation of neutral type have been made.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10330 Dhaka Univ. J. Sci. 60(1): 21-24, 2012 (January)