Tài liệu DS3 FLC Distance Learning pdf

Application Note 1211
Telecommunications
Several schools utilize distance learning to meet demands for greater variety in their
curriculum. Distance learning entails transmitting a presentation or lecture from one
location to several remote locations for students to observe.
Distance learning offers several benefits to the traditional classroom setting. It provides
for a more effective use of an educator’s time, and allows a specialist's expertise to be
spread across a wider audience. In addition, distance learning permits the sharing of
resources between institutions and increases the availability of a broader curriculum to
the student body. In short, distance learning solves educators’ problem of providing
more variety with fewer resources.
Several networks, such as DS3, analog or DS1/fractional DS1, exist to facilitate distance
learning. Of these, a DS3 network proves to be the best solution. Due to the availability
of greater bandwidth, a DS3 network requires less signal compression than a DS1
network. This leads to a higher quality video signal with DS3 transmission than with
DS1. Because DS3 transmission requires less compression than DS1, DS3 compression
equipment costs significantly less, making the DS3 network a more cost-effective video
transmission solution.
DS3 video transmission also compares favorably to analog video transmission. Analog
transmission distance limitations arise because an analog signal repeater amplifies both
the signal and any noise accompanying the signal; a digital signal can be effectively
regenerated without amplifying the accompanying noise. This advantage allows a digital
signal to be successfully transmitted over longer distances. In addition, analog video
transmission requires an analog switch, which is not normally found in a central office.
Digital cross-connect systems provide DS3 switching and are frequently available as an
integral part of the telephone company network. Therefore, digital video transmission
utilizes existing switching capabilities whereas analog video transmission requires
purchasing additional switching equipment, making digital video transmission a more
cost-effective solution.
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DS3 FLC Distance Learning

2
DS3 FLC Distance Learning
Application Note 1211
ADC offers the DS3 Fiber Loop Converter (FLC) as an effective solution for DS3 video
transmission. A DS3 FLC system consists of two identical modules interconnected by a
pair of singlemode fibers capable of transmitting a standard DS3 rate video signal. The
DS3 FLC module converts a DS3 electrical input signal into an optical output signal and
converts an optical input signal back into a DS3 electrical output signal. Two separate
fiber cables, one for each direction of transmission, provide full duplex communications.
The modules are configured in either a 1 + 1 protection mode or as a single non-
protected system. In the protection mode, a standby protect system, consisting of an
additional DS3 FLC module at each location connected by an additional fiber pair,
provides system redundancy. Failures affecting transport with this configuration cause
the DS3 signal to switch automatically from the on-line working system to the redun-
dant protect system, thereby ensuring continuous service.
The DS3 FLC module can be installed in several ADC FLC chassis. The module plugs
into either the FLC eight position mounting chassis, the FLC wall mount cabinet, or the
DS3 FLC two position horizontal mounting chassis. Each chassis has the flexibility for
various configurations. The eight position chassis allows up to four protected systems or
four non-protected systems. The four position wall mount cabinet can be configured for
up to two protected systems or two non-protected system. The two position horizontal
chassis offers up to one protected system or one non-protected system.
Description
CENTRAL OFFICE
8 POSITION UNIVERSAL
HORIZONTAL MOUNTING SHELF
SCHOOL #3
SCHOOL #1
SCHOOL #2
D

S
3
F
L
C
W
D
S
3
F
L
C
W
3/3
SWITCH
VIDEO
CODEC
OPTICAL
BUDGET
= 13 dB
OPTICAL
BUDGET
= 13 dB
FOUR POSITION
UNIVERSAL
WALL MOUNT
D
S
3
F

L
C
W
D
S
3
F
L
C
P
OPTICAL
BUDGET
= 13 dB
D
S
3
F
L
C
W
VIDEO
CODEC
T1
MULTIPLEXER
TWO POSITION
RACK MOUNT
DS3
VIDEO
SIGNAL
110V

AC
110V
AC
Q
F
L
C
W
Q
F
L
C
W
8 POSITION UNIVERSAL
HORIZONTAL MOUNTING SHELF
T1
MULTIPLEXER
AC/DC
converter
D
S
3
F
L
C
W
D
S
3
F

L
C
P
VIDEO
CODEC
D
S
3
F
L
C
W
Q
F
L
C
W
Q
F
L
C
W
Figure 1
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DS3 FLC Distance Learning Application Note 1211
Application
Figure 1 illustrates ADC DS3 FLCs used in a typical distance learning application. An
eight position chassis occupies the central office and contains several configurations.
The three DS3 FLCs in the central office allow for video transmission, with an optical
budget of not less than 13 dB, to three remote schools with a DS3 FLC in either an eight

position chassis, a four position wall-mount cabinet or a two position chassis at the
school location.
The versatility of the fiber loop converter system allows for DS1 signal transmission in
addition to DS3 video traffic. The extra slots in the remote chassis may be occupied by
other DS3 FLC modules or ADC's Quad Fiber Loop Converter (QFLC) which provides for
optical transmission of DS1 voice and data signals. Several combinations of signal
transmission exist.
The four position wall-mount cabinet has a redundant AC/DC power converter which
converts 110V AC power from a standard wall outlet to the necessary -48 V DC. This
option saves the expense of buying a rectifier.
Advantages
ADC’s DS3 FLC offers definite advantages over other DS3 transport systems. The DS3
FLC provides an alternative to OC-3 multiplexers, allowing an economical last mile DS3
transport or point-of-presence hand-off. Configuration options permit the system to
maximize facilities utilized for point-to-point or point-to-multipoint network topologies.
The DS3 FLC requires no common equipment to operate because it integrates all
functions onto a single printed circuit board. This feature reduces both start-up and
spare inventory costs. Compared to OC-3 multiplexers, the DS3 FLC offers greater
capacity for transporting a clear channel DS3. Up to four protected systems can be
hubbed out of one rack mount chassis versus three DS3 systems by an OC-3 Mux.
The DS3 FLC is a plug, play, and walk away system. No need exists for hand-held termi-
nals or craft interface access for turn-up of service. Installer training is minimal and can
be provided either by ADC or your in-house training department using ADC course
material. The same DS3 FLC module is interchangeable for the central office terminal
and the remote terminal, for either main or protect channels. One module fits all
locations and applications, thereby keeping spare inventory costs to a minimum. Each
module is a fully integrated system, simplifying trouble-shooting when needed.
At the remote end, the FLC customer premises wall mount chassis is perfect for handing
off DS3 and DS1 hicaps to end users. Installed in two of the customer premises chassis’
four slots, the QFLC can be used to deliver four protected DS1 hicap circuits; DS3 FLCs

can be installed in the other two slots to deliver one protected DS3 hicap. Or, all four
slots can be dedicated to DS3 FLCs to provide two protected DS3 hicap circuits.
Application Note 1211 11/94 Original © 1994 ADC Telecommunications, Inc. All Rights Reserved An Equal Opportunity Employer
Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products,
ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our
headquarters office in Minneapolis.
ADC Telecommunications, Inc.
4900 West 78th Street
Minneapolis, Minnesota 55435
FAX: (612) 946-3292
For U.S. Sales, Call Toll Free: 1-800-366-3891
®
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