HVAC Control in the New Millennium.pdf - HVAC.Amickracing

HVAC Control in the New MillenniumBaseband coax cable, single-strand and single-channel has been theprevalent medium.Table 7-2. Comparison of Ethernet Networks————————————————————————————————Twisted-pair NetworkLess expensive and easier to install than coaxial cableSimple node relocationSmaller geographic areaLess tolerance to crosstalk, interferenceFault isolation more difficultCoaxial Cable NetworkMore tolerance to crosstalk, interferenceMore durable and reliable than twisted-pairHarder to install and more expensive than twisted-pairNetwork with Trunk BackboneBetter performance than cascaded networkSimple expansionCan segment failed networksEasier to troubleshootHarder to traceWireless NetworkSimple to installNode relocation simpleCan be moved from site to siteLimited distanceSlower transmission speedsPossible health consequencesSusceptible to eavesdroppingPoor tolerance to interference————————————————————————————————Coaxial cable has a conducting outer metal shield enclosing andinsulated from a central metal conducting core. It is called coaxial sincethe core and shield conductors share a common axis. A single-strandcable with a tinned copper core is used which is surrounded by a foammaterial that insulates it from a tinned and braided copper shield. Coaxialcable provides an electrically balanced signal. A single coaxial cabletransmits a single channel of information.©2001 by The Fairmont Press, Inc. All rights reserved.