Specifications

Section 520-10S-WI3-203
030-101591 Rev. B
R
5
0806I3RB
If the simplex current is interrupted (open span) on the CPE
side, the 520-10SWI3 automatically re-routes the simplex cur-
rent back to the Network. When the unit is in an open span
condition, an additional 120 Ohms is added to develop the nec-
essary voltage for self-healing functionality.
2.8 Power Fuse and Alarm
The unit is equipped with a 0.25A GMT-type field-replaceable
fuse. If the front-panel Fuse Alarm LED lights, this fuse may
be open. DC power placed on pin 35 is routed to pin 25 for ex-
ternal reporting of an alarm. If AC power is placed on pin 35
and if the fuse opens, pin 25 has a half-rectified and current-
limiting AC signal.
3. CIRCUIT/FUNCTIONAL DESCRIPTION
Refer to Figure 8, the 520-10SWI3 Block Diagram, as needed,
while reading the following description of operation.
3.1 Side 1 and Side 2 Transmission Paths
The 520-10SWI3 is transformer coupled on all transmission
ports. The Span (or CPE side) transformers are center-tapped
to provide simplex current. The Network-side transformers are
also equipped with secondary lightning and surge protection
circuits. Depending on the operational mode of the unit, Side
1 and Side 2 transmission paths can be passive or active.
3.2 RCV LBO
The Receive path (Side 1) is equipped with a RCV LBO (Line
Build Out) pad used to attenuate the signal received from the
Network side of the unit if required. The RCV LBO, controlled
via option switch S3, can be set for either 0 or 7.5dB LBO.
3.3 XMT LBO
The Transmit path (Side 2) is equipped with a XMT LBO (Line
Build Out) pad used to attenuate the signal received from the
CPE side of the unit if required. The XMT LBO, controlled via
option switch S6, can be set for either 0 or 7.5dB LBO.
3.4 Framing Formats and Line Codes
The 520-10SWI3 automatically interfaces signals using either
SF, framed or unframed, and ESF code formats. The unit also
accommodates line codes using either AMI or B8ZS formats.
3.5 Code Detection
The 520-10SWI3 uses different inband codes to activate and
deactivate various features of the unit. The detection process
for these codes functions reliably with a bit-error rate of 10
−3
,
or less, on the facility.
3.6 Loss of Signal Detection
The 520-10SWI3 monitors both the Network (Side 1) and CPE
(Side 2) side transmission paths for loss of signal (LOS). If a
loss of signal is detected from either the Network side or the
CPE side, the appropriate front-panel NET LOS or CPE LOS
LED illuminates.
3.7 Operational Mode
The 520-10SWI3 is capable of operating as an Office Repeater,
a Line or Extension Repeater, or as an NIU and is configured
via option switches S1 and S2 and via the front-panel MLB but-
ton. Refer to Table 2 for setting the switches S1 and S2 for the
proper mode of operation.
Operation S2 S1
THRU (NIU or Repeater) ON ON
LOCAL (NIU or Repeater) ON OFF
SPAN (NIU or Repeater) OFF ON
Office Repeater OFF OFF
Table 2. Unit Configuration Settings
4. LOCAL PROVISIONING
Local Provisioning of the unit for the desired operation is ac-
complished via the front-panel MLB button and the various
option switches. The following paragraphs are arranged as to
describe the unit for the desired and specific operation. Refer
to the appropriate unit operation descriptions below and to
Figure 16 (Option Location Diagram), and to either Figure 9,
Figure 7 or Figure 8 (Provisioning LEDs and Status charts).
Before local provisioning of the unit for the appropriate operat-
ing mode can be done, all option switches must be set to the
appropriate settings. At this point, the craftperson can then
press and hold the front-panel MLB button IN for approximate-
ly seven seconds. After seven seconds, all six front-panel
Provisioning LEDs flashes once to indicate that the Local Provi-
sioning feature is now in progress and the craftperson can then
release the MLB button.
- NOTE -
When local provisioning begins each LED flashes, one at a time and
in 4-second intervals. This means the craftperson has four seconds in
which to enable the feature by pressing the MLB button or disable the
feature by not pressing the MLB button and letting the unit sequence
to the next LED.
4.1 Office Repeater Operation
To provision the unit as an office repeater:
S1 and S2 must be set to OFF.
S3 can be set to ON (7.5dB LBO) or OFF (0dB LBO)
S6 can be set to ON (7.5dB LBO) or OFF (0dB LBO)
While in the local provisioning mode, the PWR/RPTR Provi-
sioning LED flashes. (See Figure 6 also).
PWR/ If unit is to be configured to operate as an office re-
RPTR peater with SPAN Powering, press the MLB button
once within the 4-second time frame. The PWR/
RPTR LED illuminates and the unit sequences to the
next LED option − CPE REGEN. (See Note below).
If the office repeater mode of operation is not desired,
let the 4-second timer time out (i.e., do not press the
MLB button). The PWR/RPTR LED is off and the
unit is automatically configured to operate as an NIU
then sequences to the next LED option − CLOS ID.
(See Note below).