Valentin Topchiev

Infionix Ltd., Sofia, Bulgaria

The paper deals with the results of EDFA simulation that has been carried out to study the modes of operation and to determine the amplifier parameters' values at which maximum flatness of the gain spectrum curve is obtained. The mathematical model applied is based on the propagation equations and known parameters of the erbium-doped fiber. Depende...

The paper deals with some investigations aimed at applying compensation techniques to reduce nonlinear signal distortion in the Mach-Zehnder modulator of HFC CATV systems. The frequency distribution of second- and third-order intermodulation products of N-channel transmission systems is shown. Models of dual-parallel and dual-cascade Mach-Zehnder m...

In this paper the results of simulation of erbium-doped fiber amplifier (EDFA) characteristics are presented. The Gain, ASE power and Noise Figure variations of a fo rward pumped EDFA as functions of fiber length, injected pump power and signal input level are investigated. In this research a simulation program that solves the rate and propagation...

In this article it is presented a mathematical model of the optical channel of hybrid fiber/coaxial (HFC) system for cable television (CATV) and the results of the implemented simultaneous researches of its characteristics. The model describes the dependence of the noise level and the nonlinear distortion products in the optical channel on the para...

In this paper a method for the Mach-Zehnder modulator transfer characteristic linearization is presented. This method bases on the application of compensation scheme that includes two conventional MachZehnder modulators switched in parallel according to the input optical power and the RF drive voltage. The modulator working regime is defined so tha...

Nonlinear Distortions of the Signals in Broadband Cable Communication Systems Using Conventional Mach-Zehnder Modulator (Lidia T. Jordanova, Valentin I. Topchiev). The results of the research of the nonlinear distortions of the signals in a broadband cable communication system, caused by a conventional Mach-Zehnder modulator are presented in this p...

In this paper a theoretical basis for simulation of amplifier noise parameters is provided. On the base of propagation equations the evolution of the net system gain and the added noises due to the spontaneous Raman scattering and the double Rayleigh backscattering of the signal is simulated. A mathematical model for the carrier-to-noise ratio (CNR...

In this article are considered the principals of building up a CATV System and is given a general characteristic of the elements that build them up. It is defined the dynamic range of the signals in CATV systems and also are analyzed the reasons for its limitation. It is discussed the different sources of noises and nonlinear distortions in the opt...