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RAD Data comm 146 User Manual

Download Operation & user’s manual of RAD Data Communications 146 Modem for Free or View it Online on All-Guides.com.

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146

RAD Data Communications 2006 Catalog

Miniature short range modems offer the

same communications functions as AC-

powered modems but with fewer features,

such as limited diagnostics capability and no

BER tests. Usually they operate over shorter

distances at lower rates (normally up to

19.2 kbps). However, certain modems can

operate at data rates up to 115.2 kbps in

async transmission and up to 128 kbps in

sync transmission. Like AC-powered

modems, miniature modems are designed

to overcome distance limitations of standard

data communications interfaces such as

V.24/RS-232. They also overcome noisy

environments and provide ground isolation.

Miniature short range modems connect

computers, terminals, bridges/routers and

similar data communications devices inside

buildings, campuses or within city

boundaries. They support simple point-to-

point communications as well as complex

multipoint campus-wide systems. They also

support flow control when connected to a

printer or a multiplexer.

Typical communications problems, such as

distance limitations and noise, are overcome

by using special signal modulation and line

equalization techniques that allow for

error-free transmission over longer

distances. RAD miniature modems have

transformers to isolate the equipment from

the line and ensure safety. The transformers

are rated at over 1,500 VRMS and are

approved by carriers worldwide for

connection to their lines.

What is the difference between

interface-powered and AC-powered

modems?

Interface-powered and AC-powered

modems perform the same basic

communications functions. Interface-

powered modems incorporate innovative

VLSI and hybrid circuitry that enable them to

consume very little power. These modems

draw power from the interface signals

without loading the adjacent equipment or

interfering with normal operation. For

computers that do not support control

signals, there are special models that derive

their power solely from the data signals.

How do you select the right modem for

your application?

Several factors should be considered when

selecting a modem:

• Computer/DTE interface: V.24/RS-232,

V.35, etc.

• Communication method: sync, async or

both

• Data rate

• Distance

• Media: twisted pair, coax, fiber

• Point-to-point or multipoint application

• Control signals (does the application

require transmission of data only, or also

transmission of one or more control

signals?)

• Environment (is the environment noisy?)

A Quick Reference Guide on pages 158-159

will help you select the most suitable

modem for your application.

Miniature short range modems

offer a simple, low cost and highly

reliable method to connect digital

devices in a local, campus or

metropolitan environment. They

also offer very easy installation

since in many cases they do not

require AC power, but derive their

power from the interface signals.

Miniature Modems

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