Specifications

Page 1–4
FOCUS System Manual
Future Capabilities — FOCUS is designed
with the future in mind. The use of
position-independent channel slots permits
adding or modifying features as required in
the future.
1.7 Transceivers
The T1/E1 link interfaces between terminals may
be either optical or electrical. Once the communi-
cations medium for a particular link is known, the
appropriate transceiver can be selected. Some
examples of links include fiber optics, microwave,
or other digital transmission paths. This gives the
system designer a high degree of flexibility.
1.7.1 Optical Transceiver
The optical Interface is used when two fiber optic
cables within a span are dedicated to connecting
two FOCUS terminals. The interface is provided
by fiber optic transceiver modules. Single or dual
configurations are available for each. The fiber
versions are available with hot-standby optical
components.
The 1300 nm LASER version (13LAS) provides a
system gain of up to 36dB for single mode fiber. It
uses onboard ST connectors for both transmit and
receive paths. (SC or FC connectors and 1550 nm
lasers are also available).
The frame format used for T1 systems is extended
super-frame (ESF) & HDB3 for E1 Systems. The
optical line format is bi-phase mark encoded.
Using the ESF (or HDB3) format enables all DS0
channels between nodes to be 64 kbps clear
channels. It also permits terminals to communi-
cate operational information necessary for
network reconfiguration, remote alarms, and other
maintenance functions (discussed later). The
optical transceivers can be combined as pairs to
provide for hot standby optical paths.
1.7.2 Electrical Transceivers
The DE1 Module is used when a span is
connected by a higher rate communication
system, such as T2, T3, Sonet or E2, E3, SDH
into fiber optic cables or digital microwave. This
enables FOCUS to be an access multiplexer into
one of the DS1 (or E1) ports from the higher rate
multiplexer. The electrical interfaces conform to
AT&T & CCITT standards.
Distances up to 650 feet (200 meters) between
FOCUS and the higher rate multiplexer system are
supported. The line format for this interface is
B8ZS for T1. This enables matching of the DS0
circuits between FOCUS and transmission
equipment that supports Extended Super Frame
(ESF) is also supported. HDB3 is used with E1
systems.
1.8 Maintenance Module
(MV2, MV3, MV4, MV5)
The Maintenance Module, which contains a
digital and cross connect system, comprises a
main board and an auxiliary board. It provides an
interface through which you can configure and
monitor your FOCUS system.
The module maintains and stores configuration
data for the entire chassis, including all resident
system and channel modules. Using a high-speed
watchdog timer, it monitors the health of your
system, giving you information on the system’s
operation. Three digital time/space crosspoint
switches: U3, U4, and U5, exchange data with the
programmable peripheral interface U6 on an 8-bit
data line.
The Maintenance Module includes:
• An onboard microprocessor to control the
switching system
•Adigital telephone interface to provide
party line telephone and modem communi-
cations
•A9-pin RS-232 craft interface port for PC
communications with FOCUS.
• Its own memory with a lithium battery
backup and real-time clock, enabling it to
operate independently from the system
•Ahigh-speed watchdog timer that monitors
the CPU
•A high-level serial communications
controller
• Flash Memory (MV4, MV5)
•
Second serial port (MV4, MV5)