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

HVAC Control in the New Millenniumkbps dial-up modem could be done in under 5 seconds with a cablemodem. Most cable modems can speed up file transfers by 250 to1000%.Cable modem service cannot abate Internet traffic that occursoutside its own network. But, many services cache recently visitedWeb sites on their own servers, so popular pages and files can downloadmore quickly.Cable performance can match and sometimes beat that of moreexpensive T1 lines. Cable modem service can deliver cheaper speedin part because it does not give you a dedicated fast connection tothe Internet. It divides the total cable which may be capable of transferrates up to 36 mbps between users on your node. Depending onyour service provider and your location, you might share your connectionwith hundreds or even thousands of other users.If too many users on your node hit the Internet simultaneously,your connection could suffer. Some cable modem users reported incidentswhere performance dropped off to 2 or 3 kbps. Cable modemscan add more capacity. They have the architecture to allow highercapacity.Internet2Internet2 will connect only academic and government users. Therest of the Internet will benefit indirectly as high-bandwidth Internet2applications trickle down. There will be greatly improved multimediaand video conferencing capabilities. Internet2 groups are developingtechniques for tagging voice data packets so they get a higher priorityas they pass through the network.Another promising development is occurring in a branch ofphysics called photonics. Today, information travels down fiberopticcables in the form of laser-generated light. Photonics involves ways ofhandling these light waves to increase the fiber’s transmission capabilities.One technique is Dense Wave Division Multiplexing (DWDM). Itsends multiple frequencies of light down the same fiber at the sametime. Sprint uses DWDM to increase the company’s fiber capacity bya factor of 32.In the future it may be able to increase capacity by a factor of©2001 by The Fairmont Press, Inc. All rights reserved.