User's Manual

Configuring Modems for Use with Leased Lines
D-6 apC/8X Technical Manual
Configuring Modems for Use with Leased Lines
For use with a leased line, the apC/8X panel must be set for a direct
connection instead of dial up. Set SW3-1 to ON, SW3-2 to OFF, and power
on the apC/8X.
It is important to understand the decibel (dB) attenuation specifications of the
leased line to be used. Depending on the proximity of the modem to the
source of the leased line, there may be a requirement to attenuate or de-tune
the signal strength. For details about attenuation requirements or “buildout,”
contact the provider /carrier.
Buildout is the amount of signal attenuation or resistance applied to the
Leased Line. The shorter the distance between equipment, the stronger the
signal and the greater the need for signal attenuation. The further the distance
between equipment, the less attenuation is needed so a stronger signal can be
received.
Figure D.3
shows some common scenarios. In most cases, if the modem is
close to the source, it will have to attenuated by -15 db. If the modem is a long
distance from the source, it will be attenuated by -9 db. These settings are
available on the OEM MT2834BL modem using SW3.
Certain carriers have a weaker signal and must be attenuated at a different
rate. In these cases, if the modem is a long distance away, the signal should
not be attenuated at all. If the modem is very close to the source then it should
be attenuated at -10 db rather than -15 db. The MultiTech MT1932BL
provides these settings using SW3.
Note: The MT1932BL does not have the OEM firmware of the
MT2834BL, and should only be used for leased line connections,
not for dialup.