Theoretical and available transmission capacity of UTP

The paper presents the results of research in the field of digital signal transmission on a metal twisted pair. The principal goal is to determine the ratio between the theoretical and the available transmission capacity of a two-wire line. The theoretical transmission capacity determines maximum error-free transmission, but in installed transmission systems there is always a certain acceptable error rate, which depends on the type of service. The available capacity of a two-wire line is therefore the real achievable transmission speed subject to certain limitations of a technological nature and subject to the type of service. In order to compare available capacity we selected several hypothetical models of a transmission system: coded and uncoded multicarrier and baseband transmission, and uncoded transmission with a simple two-level line code.