Items of № 3, 2009

The Electrosvyaz Magazine is one of the leading science & technical magazines in Russia.

Discussing the problem of introducing multipart tariffs


In this article the problem of favorable and limitation transmission conditions for the telecommunications services on the base of multirate taxes are described, also the direct transmission organization methodic are concerned.

Key words: tariff, telecommunications, services.

Urban radio link communication trends


This paper describes new features of current urban microwave radio link. The new radio system are able to flexible dividing radio bandwidth between TDM and Ethernet traffic and transmit this traffic with great reliability. Analysis in this paper provides useful guideline for choosing the best options at the current microwave equipment. Tables 2, Bibliography.

Key words: Urban radio link communication, QAM modulation, flexible dividing radio bandwidth between TDM and Ethernet traffic.

Searching for an optimum modulation procedure for corporate mobile communication systems


In a number of radio communication systems, such as VDL4 [1], for increase of throughput of a radio channel signal GFSK is used, however characteristics of this signal in widely known literature are not considered. There is only a small mention of this kind of modulation in [5]. The given complication has revealed necessity to investigate this kind of modulation in detail.

The results of experimental research and comparative analysis of characteristics of signals with frequency shift keying FSK and MSK in spectral domain are shown. The purpose of this work was:

— to investigate the GFSK-0.25 signal spectral parametres and to compare it with the GMSK-0.25 signal spectral parametres;

— to estimate influence of the frequency response curve shape of quartz-crystal filters are a part of transceivers, on accuracy of GFSK-0.25 signal forming.

The paper presents that combined using of FSK and high order quartz-crystal filters allow to apply highly economical power amplifiers and double the digital data transfer rate.

Key words: modulation, simulation, mobile systems, electromagnetic compatibility, GFSK-signal.ъ

IT networks simulation opportunities and effectiveness


In this paper evaluated functionality of the network using OPNET software in two different corporate networks. Behavior of each of the networks simulated with the introduction of new services or with increased load on the network. The analysis of reliability and economic efficiency of the network provider was made. Assessing the functioning of the network was carried out using the following parameters: the load on the communication channels between servers and routers and between routers and the subscriber equipment, QoS, delay when viewing web-pages and delay in the transmission of audio traffic. The introduction of new services in a network slightly increases the load on the network, and replacement of equipment in another network increase the number of subscribers, reduce ISP channel load, provide high quality transmission of voice. The results are verified using simulations of both networks.

Key words: IT network, simulation, capacity, communications channel, quality of service.

Auxiliary error estimation of bipolar current line’s resistance measurements with interference present


The design procedure of an additional error of the two-terminal electric chains impedance measurement by a method of the ampermeter-voltmeter with indirect definition of the current, caused by additive harmonious hindrance action is offered. Variants consistent amplitude diode detector and synchronous converter on FET’s are considered. It is shown that the two-terminal chains impedance measurement device with synchronous converters based on КП305 type FET possesses on 12 dB the increased range of a hindrance amplitudes at an identical additional error of measurement.

Key words: error estimation, interference, ampermeter-voltmeter method.

Feeder input resistance assessment procedure


A technique, which allows to calculate a wideband amplifier load in cases, when the amplifier output impedance is not matched with the antenna feeder wave impedance, taking into account the amplifier feeder output and antenna input impedances, as well as feeder parameters, is proposed.

Key words: wideband amplifier, matching, feeder.

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