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

HVAC Control in the New Millenniumsince others will use the same routers and network wires in their transmission.Dial-up Internet AccessThe easy and most popular way to get network access is to get anaccount on a computer that already has dedicated access. Then you useyour computer to log in to this system. Dial-up access is not as good ashaving your own connection, but it is easier and less costly to set up.Your computer does not actually become part of the Internet. It accessesa service computer from an Internet service provider that is permanentlyconnected to the network. There are many organizations that providethis type of service now. They are generally known as Internet ServiceProviders (ISPs).Future Internet ServiceA significant number of Internet users will access the net over cableor DSL connections that are up to 50 times faster than 56-kbps modems.Many people will use the Internet for video conferencing, telephony,telecommuting, and on-line control monitoring applications. These applicationsdemand raw bandwidth and a level of reliability the presentInternet cannot provide. In the near future the Net will have to carrymore data than it does today and with more reliability.At 56 kbps, today’s modems are going about as fast as today’sphone lines will let them. Access speeds vary from 28.8 kbps, or slower,for older modems, to 56 kbps for newer models and for some users, 256kbps to 1.5 mbps for DSL, and up to 3 mbps for cable modems. Thereare a variety of broadband options, including T1 lines and other dedicated,high-speed connections (Table 9-4).Cable and DSL are two technologies trying to replace traditionalmodem connections. Current cable connections can manage speeds upto 3 mbps. DSL implementations run between 256 kbps and 1.5 mbps.Another option is Sprint’s Integrated On-demand Network (ION)which can deliver voice, video, and data at speeds up to 620 mbps. AnION Integrated Service Hub is wired into your phone jack and attachedto an Ethernet card in the PC.©2001 by The Fairmont Press, Inc. All rights reserved.