High Speed Communication; Modem Technology - Diamond SupraExpress 56e Manual

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This section addresses some of the issues that you should be aware of as you work with modems that
communicate at speeds of 33,600 bps and above.
This section discusses the following topics:
• 56K M
ODEM
• 33,600 C
BPS
• A
SYMMETRIC
• S
ELECTING A
C
ONNECTIONS
• R R
ATE ENEGOTIATION
• H F
ARDWARE
56K M
ODEM
Communicating at 56,000 bps is the new lightning fast modem technology which offers the most
rapid transmission speeds available over ordinary phone lines. With 56K technology, you can surf
the Internet and explore web sites at up to twice the speed of 28,800 bps modems.
Current analog modems allow for a maximum data connection of 33,600 bps between two modems
or a single modem and an Internet Service Provider (ISP). The maximum theoretical transmission
rate across the Public Switched Telephone Network (PSTN) is roughly 35,000 bps.
This normal data transmission rate is described by Shannon's Law which calculates the fastest
speeds at which data can flow across the twisted pair of copper wires between two analog sites. Your
ISP is connected to the phone company Central Office which converts the signals from analog to
digital upon receipt. This digital signal is transmitted through the PSTN to the Central Office
located near you. Then it is converted once again from digital to analog and delivered to your home
or office.
C
T
ECHNOLOGY
ONNECTIONS
D R
ATA ATES
M
ODULATION TO
C
LOW ONTROL
T
ECHNOLOGY
H
IGH
OMMUNICATION
C H S
ONTROL IGH
S
PEED
PEED
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