Tài liệu Operating Fiber Loop Converters Over Multimode Fiber pptx

Application Note 1206Telecommunications Fiber Loop Converters are sometimes required to operate over multimode fiber because an existing span of installed multimode fiber may already be

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Application Note 1206

Telecommunications

Fiber Loop Converters are sometimes required to operate over multimode fiber because

an existing span of installed multimode fiber may already be in place between two points requiring FLC transmission The FLCs were designed for use over singlemode fiber, and

if there is a choice, singlemode fiber should be installed However, FLC operation over multimode fiber is possible and, in fact, is a functioning application with several custom-ers LAN applications over short distances have been successful The following aspects of this application require attention

A 10 meter (33') singlemode jumper with a physical finish on the connector endfaces should be installed in the FLC transmitter This singlemode jumper can then be con-nected to the multimode fiber in the span To prevent higher order modes from being launched directly into the multimode fiber, a minimum of 10 meters (33') of singlemode fiber is required out of the transmitter

The multimode fiber can terminate directly into the FLC’s receiver at the other end of the span

Ideally, the only connection in the span will be the junction from singlemode to multimode If fiber joining is required anywhere else in the span, fusion splicing is recommended

Because the connectors in a multimode span are not required to be in physical contact at the fiber endfaces, Fresnel reflections and alignment mismatches can degrade perfor-mance to an unacceptable level If connectors are in the span, they should be of

singlemode quality with physically contacting, radius-polished fiber endfaces Multimode SMA and biconic fiber connectors are unacceptable D4, SC, FC and ST® connectors can

be used, if the endface polish and the concentricity tolerances are singlemode quality The number of connectors should be kept to the absolute minimum

Launch Conditions

Connections

in the Span

®

Operating Fiber Loop Converters Over Multimode Fiber

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Multimode fiber has higher loss per distance properties than singlemode fiber Tradi-tional calculations of optical budget for the span will not take into account the pulse spreading and interference resulting from sending a singlemode signal down a multi-mode fiber The optical budget for the DS3 FLC is 13 dB at 1300 nm wavelength Standard Corning 62.5 mm fiber has attenuation of 0.7 dB/km This works out to a theoretical capability of 18.5 km (11.5 miles) based on optical budget alone When bandwidth is considered, the theoretical distance limit decreases Bandwidth is not a limiting factor for T1/E1 FLCs and QFLCs Bandwidth may become the limiting factor when the bit rate increases to DS3 rates or above

The bandwidth of the fiber, which is measured in the units of MHz-kilometers, should be known Standard Corning graded-index 62.5 micron core multimode fiber typically exhibits a bandwidth of 400 MHz/km This means that an FLC operating at 51.84 Mbps (which translates into an analog rate of 25.92 MHz) is theoretically capable of transmit-ting over a distance of 15.43 km (9.56 miles) However, more conservative distances are recommended See Table 1 (which lists the minimum of 200 MHz/km) and Table 2 for the theoretical limits of the FLCs The bandwidth cells of the fibers listed in the tables are minimums Fiber of greater bandwidth capacity is available from the manufactur-ers QLX modules operate at the same rates as the QFLC

DS3 FLCs have been successfully implemented over a distance of 10.0 km (6.2 miles on multimode fiber)

Both attenuation and bandwidth of the multimode fiber should be examined and the limits calculated before installing FLCs and QLXs for use over multimode fiber Charac-terizing the fiber plant or records indicating the exact fiber type will help to determine how well FLCs and QLXs can work over multimode fiber Call ADC Application Engineer-ing at 1-800-366-3889 before purchasEngineer-ing FLCs or QLXs for use over multimode fiber

Optical Budget,

Bandwidth and Fiber

Properties

ADC CATALOG NUMBER

Multimode Fiber

TABLE 1: Theoretical Span Calculation for FLCs Over Multimode Fiber

CORNING 50/125 Att.: 0.80 dB/km BW: min 400 MHz.km

Theoretical Capacity:

Attenuation: 16.2 km / 10.0 miles Bandwidth: 15.4 km / 9.56 miles (25.920 MHz)

CORNING 62.5/125 Att.: 0.70 dB/km BW: min 200 MHz.km

CORNING 100/140 Att.: 2.00 dB/km BW: min 100 MHz.km

AT & T 62.5 Att.: 1.00 dB/km BW: min 500 MHz.km

BerkTek 62.5/125 Att.: 1.00 dB/km BW: 500 MHz.km

T3/FLC DS3-B1LDFC(SC)

13 dB at 1300 nm

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CORNING 50/125

Att.: 0.80 dB/km

BW: 400 MHz/km

CORNING 62.5/125

Att.: 0.70 dB/km

BW: 200 MHz/km

CORNING 100/140

Att.: 2.00 dB/km

BW: 100 MHz/km

AT&T 62.5

Att.: 1.00 dB/km

BW: 500 MHz/km

BerkTek 62.5/125

Att.: 1.00 dB/km

BW: 500 MHz/km

28.7 km 17.7 miles

32.8 km 20.3 miles

11.5 km 7.12 miles

23.0 km 13.6 miles

23.0 km 14.3 miles

T1/DFLC F1544-20XR

23 dB/1300nm

27.5 km 17.0 miles

31.4 km 19.4 miles

11.0 km 6.81 miles

22.0 km 13.6 miles

T1/QLX QLX-SPXSC(FC)A2

22 dB/1300nm

27.5 km 17.0 miles

31.4 km 19.4 miles

11.0 km 6.81 miles

22.0 km 13.6 miles

T1/QFLC QFC-D3LDSC(FC)

22 dB/1300nm

ADC CATALOG

NUMBER

Multimode Fiber

27.5 km 17.0 miles

31.4 km 19.4 miles

11.0 km 6.81 miles

22.0 km 13.6 miles

E1/DFLC F2048-20M(R)XR

22 dB/1300 nm

TABLE 2: TheoretIcal Span Calculation for FLCs Over Multimode Fiber

Contact ADC Application Engineering at 1-800-366-3889 for additional assistance.

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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

®

Telecommunications

International Sales Offices: Belgium 32-2-721-5282 • United Kingdom

44-734-441955 • Montreal, Quebec (514) 677-9166 • Vancouver, BC

(604) 270-1675 • Toronto, Ont (905) 629-3104 • Ottawa, Ont (613)

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Mexico City, Mexico 525-658-4519 • Sydney, Australia 61-2-975-1499

Tiêu đề	Operating fiber loop converters over multimode fiber
Chuyên ngành	Telecommunications
Thể loại	Application note

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