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NETMATION
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Telecommunications
Introduction
Cables
RS232, Parallel, Category Patch, SCSI, IBM Patch,
Video, Audio, Voice.
Networking
Patch Panels, Hubs, Repeaters, Racks, Trancievers,
Punchdown Blocks, Category Inserts, Wall Plates,
Surface Boxes
Connectors
D-Subminiature, Modular Plugs, BNC/Twinax, Fiber Optic,
SCSI, Ribbon Mount, Panel Mount, Crimp/Solder, Network.
Bulk Wire
Category Rated, Multi Pair, MultiConductor, Voice, Data,
Coaxial, Fiber Optic, Twinaxial, Ribbon, Line Cord.
Accessories
Switch Boxes, Line Boosters, Convertors, Surge Protectors,
Splitters, Modular Adapters, Gender Changers, Adapters,
Sharing Devices.
Terminators
BNC, SCSI, VGA, PhoneNet, Twinaxial
History of Telecommunications
The modem was certainly a big breakthrough in computer technology.
It allowed computers to communicate with each other by converting
their digital communications into an analog format to travel
through the public phone network. But there is a limit to the
amount of information that a common analog telephone line can
hold. Currently, it is about 56 kbps.
ISDN
ISDN allows multiple digital channels to be operated
simultaneously through the same regular phone jack in a home or
office. The change comes about when the telephone company's
switches are upgraded to handle digital calls. Therefore, the same
wiring can be used, but a different signal is transmitted across
the line. Previously, it was necessary to have a phone line for
each device you wished to use simultaneously. For example, one
line each for the phone, fax, computer, and live video conference.
Transferring a file to someone while talking on the phone, and
seeing their live picture on a video screen would require several
expensive phone lines. ISDN technically refers to a specific set
of services provided through a limited and standardized set of
interfaces. This architecture provides a number of integrated
services currently provided by separate networks.
ISDN adds capabilities not found in standard phone service. The
main feature is that instead of the phone company sending a ring
voltage signal to ring the bell in your phone, it sends a digital
package that tells who is calling (if available), what type of
call it is (data/voice), and what number was dialed (if multiple
numbers are used for a single line). ISDN phone equipment is then
capable of making intelligent decisions on how to answer the call.
In the case of a data call, baud rate and protocol information is
also sent, making the connection instantaneous.
Many companies are using ISDN where service is not yet available.
This is possible by using other digital communications methods at
the local level. A common method is to use a T1 line, or a
fractional T1 line to connect the computing facility to a switch
that does provide ISDN access. A T1 line multiplexes twenty-four
64 kbps channels together over a single line. A fractional T1 line
is simply a chosen portion of the full T1 circuit.
Switched 56 Digital Data
Switched 56 represents a fast, yet cost-efficient method of
transferring data. The service taps the public network, taking
advantage of the recent investments telephone companies have made
in digital and fiber-optic communications.
The "56" of Switched 56 stands for the fast data rate of 56
kilobits per second. "Switched" refers to your ability to dial
and receive switched data calls just as you would with a voice
telephone line. Switched 56 combines high speed with the
widespread availability and low usage cost of voice. Once
Switched 56 is installed, you simply dial another user's
Switched 56 number to transmit full duplex 56 Kbps digital data.
Switched 56 is a fast, inexpensive way to transport data
digitally. Cost effectiveness. High speed. Widespread
availability. Flexibility. Extensive Applications. For all
these reasons, data communications managers, PC power users, LAN
managers, broadcasters and video conference users are making
Switched 56 the most popular of the Switched Digital Services.
Frame Relay
Cable Modems
However it is expected that when products and services become
available they will be geared towards the consumer market first
rather than the businesses. And, it remains to be seen the level
of support systems the cable companies will be able to provide
corporations.
T1 Line
If you're using switched services, like Switched 56 (a switched
data service transmitting at 56 Kbps), you can use T-1 lines for
about the same cost of Switched 56, depending on number of lines
and distance between sites. In some cases you'll save money with
T-1. In other cases you'll pay slightly more. The costs vary,
depending on applications and network needs. Another neat network
feature T-1 provides is user-defined bandwidth allocation.
Managers can assign network resources and channels based on where
and how they're needed.
Asynchronous Transfer Mode (ATM)
ATM is a networking technology that has very high expectations to
improve transmission speeds. It has the capability to condense
and transmit video, voice and data over a single line. Its speeds
far outrate those of LANs using Token Rings or Ethernet. However
the speed does come with a higher price tag than traditional
transmission alternatives. ATM is gaining hold in market niches,
such as print production, video, and TV broadcast applications,
medical imaging, financial transactions, and seismic analysis.
Areas which companies need to move large amounts of data-quickly
and where the need for speed far outweighs the higher price tag.
For technology managers, the variety of choices is only made more
confusing by the emergence of ATM. Often it is very hard to
determine the best alternative for a particular company's needs.
There are more network choices than ever.
Applications of Telecommunications
One of the most talked about applications which needs lots of
bandwidth is video conferencing. Previously, systems cost well
over $100,000. Now the concept of personal, desktop video
conferencing is available using common personal computers and
workstations. One channel is used for voice, and the other channel
is used for the display of moving video pictures. The price for
video conferencing is dropping so quickly, that it is currently
affordable to most businesses.
Along similar lines, is a shared electronic chalk board. Users can
talk in a conference arrangement and also illustrate written ideas
to remote locations. Slide presentations could also be given in
this manner.
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