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STRUCTURE OF THE SYMMETRIC CABLE OF «LONG» ETHERNET
Andrey B. Semenov, professor, Moscow State University of Civil Engineering, Moscow, Russia,
andre52.55@mail.ru
Maria S. Bylina, assistant professor, The Bonch-Bruevich Saint-Petersburg state university of communication, Saint-Petersburg, Russia, BylinaMaria@mail.ru
Evgeny V. Kandziouba, graduate student, Moscow Technical University of Communications and Informatics, Moscow, Russia, ekandziouba@gmail.com
Abstract
The paper analyzes the possibilities of increasing the length of channels built using Fast Ethernet network interfaces and a balanced cable as the transmission medium. It is shown that the main factors limiting the length of the channel are the attenuation coefficient and near end cross-talk loss coefficient. The analysis of the degree of influence of each of these factors on the length of the channel. It has been established that the main factor limiting the length of the chan-nel is the attenuation coefficient.
Expressions are presented for estimating the values of the individual components of the at-tenuation coefficient of a balanced cables channel, characterizing the losses in metal conductors, insulation losses, as well as losses due to the presence of a shield. The results of the calculation of the dependence of the attenuation coefficient and impedance on the frequency for shielded and unshielded twisted pair cable with the same impedance are presented. It is shown that in the frequency range under consideration, the shielding of symmetrical channel is impractical.
Three ways to reduce the attenuation coefficient by changing the design of an unshielded balanced channel — increasing the diameter of the conductive wires, increasing the impedance and increasing the twisting pitch — are considered and analyzed. It is shown that an increase in the impedance of the channel can effectively reduce its attenuation coefficient, but the applica-tion of this method is limited, since it can disturb the matching of the channel and lead to incom-patibility with existing detachable connectors. It is shown that increasing the twist pitch of the circuit can reduce the attenuation coefficient, but leads to an increase in noise due to mutual in-fluences. In the considered frequency range, it is permissible to increase the twist pitch of the chain to 15-17 mm with a gain in attenuation coefficient up to 8%. It is shown that increasing the diameter of the wires conductor effectively reduces the attenuation coefficient. The maximum diameter of the core, which maintains compatibility with existing connectors, is 0.8 mm.
Studies have shown the feasibility of using extended lengths of balanced cable with un-shielded twisted pairs on Fast Ethernet channel and allowed us to formulate the following rec-ommendations for changing their design: increasing the diameter of conductor to 0.64 mm and using the maximum possible twist pitch.
The implementation of the results will improve the efficiency of building communication lines of local information and telecommunication systems.
Keywords: balanced cable, twisted pair, shielding, attenuation coefficient, Fast Ethernet, channel.
References
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Information about authors:
Andrey B. Semenov, professor, Moscow State University of Civil Engineering, Moscow, Russia
Maria S. Bylina, assistant professor, The Bonch-Bruevich Saint-Petersburg state university of communication, Saint-Petersburg, Russia
Evgeny V. Kandziouba, graduate student, Moscow Technical University of Communications and Informatics, Moscow, Russia