The Model 279 provides transparent conversion between fiber optic
devices utilizing multi-mode fiber and those with single-mode fiber.
Single-mode fiber can transmit data over much longer distances than is
possible with multi-mode fiber. It accomplishes this by limiting the
amount of power lost through leakage in the walls of the fiber and using
1300 nm wavelength emission which has less attenuation than 850 nm.
Thus, this converter regenerates signal strength and is used to extend
the distance far beyond the specification for multi-mode fiber. The
Model 279 can also be used when the optical fiber type of the equipment
is not compatible with the installed fiber optic cable.
Features of the Model 279 include the ability to operate from DC to 2.5
MBPS. This allows a variety of applications to take advantage of the
transmission capability of the device and fiber cable. A loss budget of
15 dB is provided which equates to a distance of approximately 20
kilometers. Since operation is allowed at DC there is no clocking
information that the Model 279 can use to perform automatic gain
control. Therefore, the gain is user-controlled by a Line Loss switch
and, once set, does not have to be changed. Once the single-mode line is
installed its length is fixed. Four positions on the Line Loss switch
allow selection of 2, 5, 10 and 15 dB of loss. Four LEDís are provided
to give a visual indication of the selected line loss. The units are
used in pairs, interconnected on the single-mode side.
The Model 279 is powered
by a wall-mounted DC adapter that develops 12 V. By use of an internal
DC-to-DC converter the user can supply any DC voltage from +8 V to +36 V
for those situations where AC is not available. The fiber optic ports of
the Model 279 are provided on ST connectors. The product is designed for
inline mounting. Itís relatively small size allows for placement in
virtually any installation.