Adc Link Loss Testing (adcp-90-388)

Transcript

ADC Link Loss Testing ADCP-90-388 • Issue 1 • 2/2009 Content Page INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 LINK LOSS TESTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 2.1 Initial Turn-up (Testing with a Laser Source and Power Meter). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Power Meter Test and Troubleshoot – High Loss Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3 Power Meter/Laser Source Testing and Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.4 Power Meter Test and Troubleshoot – Expected Loss and Optical Budget Calculations. . . . . . . . . . . . . . . . . . 11 2.5 Testing with Power Meter and Laser Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 CUSTOMER INFORMATION AND ASSISTANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 INTRODUCTION These instructions provide information for Link Loss Testing single mode and multimode fiber cable assemblies. Revision History ISSUE DATE 1 2/2009 REASON FOR CHANGE Original List of Changes PAGE IDENTIFIER All – DESCRIPTION OF CHANGE New Trademark Information ADC is a registered trademark of ADC Telecommunications, Inc., OptiTip is a trademark Corning Cable Systems Brands, Inc. 1454359 Rev A Page 1 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 Admonishments Important safety admonishments are used throughout this manual to warn of possible hazards to persons or equipment. An admonishment identifies a possible hazard and then explains what may happen if the hazard is not avoided. The admonishments — in the form of Dangers, Warnings, and Cautions — must be followed at all times. These warnings are flagged by use of the triangular alert icon (seen below), and are listed in descending order of severity of injury or damage and likelihood of occurrence. Danger: Danger is used to indicate the presence of a hazard that will cause severe personal injury, death, or substantial property damage if the hazard is not avoided. Warning: Warning is used to indicate the presence of a hazard that can cause severe personal injury, death, or substantial property damage if the hazard is not avoided. Caution: Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or property damage if the hazard is not avoided. General Safety Precautions Caution: Fiber optic cables may be damaged if bent or curved to a radius that is less than the recommended minimum bend radius. Always observe the recommended bend radius limit when installing fiber optic cables and patch cords. Danger: Exposure to laser radiation can seriously damage the retina of the eye. Do not look into the ends of any optical fiber. Do not assume the laser power is turned-off or that the fiber is disconnected at the other end. Caution: Improper handling can damage fiber optic cables. Do not bend fiber optic cable more sharply than the minimum recommended bend radius specified by the cable manufacturer. Do not apply more pulling force to the cable than specified. Do not compress the fiber or allow it to kink. Warning: Invisible infrared radiation can seriously damage the retina of your eye. Do not look into the launching (output) end of an active fiber. A clean, protective cap or hood MUST be immediately placed over any radiating bulkhead receptacle or optical connector to avoid exposure to potentially dangerous amounts of radiation. This practice also helps to prevent contamination of connectors and adapters. 1 GENERAL INFORMATION This procedure will assist field personnel in link loss testing of fiber cable assemblies. 2 LINK LOSS TESTING Link loss testing connections are similar to a continuity test. Page 2 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 2.1 Initial Turn-up (Testing with a Laser Source and Power Meter) Danger: Exposure to laser radiation can seriously damage the retina of the eye. Do not look into the ends of any optical fiber. Do not assume the laser power is turned-off or that the fiber is disconnected at the other end. The Power Meter and Laser/Light Source are connected to the fiber cable by a single fiber (SM or MM) patch cord with appropriate connectors on both ends for connection to the test equipment and the fiber panel to be tested. This may require a standard SC to SC patch cord or a hybrid with SC on one end and LC on the opposite end. Before starting any testing, make sure you have all the necessary equipment required to perform the tests, including the correct fiber patch cords. The following test requires two technicians, one at each end of the fiber that is being tested. 1. Connect a Power Meter and Laser/Light Source as shown in Figure 2 using two single patch cords with an adapter between them. Reference the test set-up to zero. 2. At one end of the fiber cable, connect the Laser/Light Source to the designated fiber in the fiber panel or fiber frame. 3. At the opposite end of the fiber cable, connect the Power Meter to the same designated fiber in the fiber panel or fiber frame. 4. Send appropriate wavelength and power signal from Laser/Light Source. Measure received signal (loss as referenced to zero) at Power Meter and document the results. 5. Complete a bi-directional test by repeating Steps 1–4. This is done by reversing Laser/Light Source and Power Meter, after completing the tests, average the results and document findings. 6. Repeat above steps on each fiber in the network, documenting all results. 7. Review all test results. Any result values under the expected or specified loss for the cable plant will require further testing. 2.2 Power Meter Test and Troubleshoot – High Loss Events • Clean all accessible connectors and those affected by test set-up. Re-test after cleaning. • If possible, test smaller portions of the cable plant until the high loss area is located. • Excessive loss is usually an indication of a micro or macro bend, faulty or dirty connection, poor splice, or possible break in fiber. At this point a visible light source or an OTDR should be used to further isolate the trouble. 2.3 Power Meter/Laser Source Testing and Troubleshooting Required tools and supplies: • • • • • • Power Meter Laser Source Patch Cords Fiber Optic Cleaning Kit Spare Bulkhead Adapters Fiber End-face Scope (200x magnification or better) Page 3 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 Optional Tools: • • • • Return Loss Meter Optical Time Domain Reflectometer (OTDR) Light Source Launch Cables Typical settings for Single Mode span loss troubleshooting and testing are: • • • • 1550nm wavelength dBm setting for power meter CW (Continuous Wave) setting for laser source Laser source launch power is normally –8dBm to –7dBm (158uW to 200uW) Some power meters have an automatic mode, for the tests being performed in this document it is better to operate in the manual mode. Manual mode allows greater freedom to vary test modes, which is more important during troubleshooting than during acceptance testing. If troubleshooting a quality issue use settings as close as possible to the settings at which the customer or contractor discovered issues. Typical reference set-up based on a one jumper method, is shown in Figure 1. This set-up references the loss of the test equipment connector ports and one jumper used for the test. The method also allows for a quick check to ensure the test set-up is correct. ONE JUMPER METHOD PWR MTR LSR SRC Figure 1. Test Set-Up One Jumper When the Reference is established with the above set-up, a check may be performed. Place another jumper between the Laser Source and Power Meter and measure the loss. A loss equal to the one connector should be as expected. Typically for a SM connection this will be less than 0.5dB and less than 0.75dB for a MM. See Figure 2. Page 4 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 TYPICALLY LESS THAN 0.5dB (SM) 0.75dB (MM) LSR SRC PWR MTR Figure 2. Test Set-Up Two Jumpers 2.3.1 Laser Source Note: Tool and meter pictures/names are shown as examples only and are not intended to be recommended brands. There are several manufacturers of these products. Always use properly calibrated tools and meters. Figure 3 shows a Laser Source device with the major functions noted. LASER WAVELENGTH INDICATOR 1310NM IS RED LED AND 1550NM IS GREEN LED LASER OFF, 1310NM (RED LED) OR 1550NM (GREEN LED) CONTINUOUS WAVE LASER OR 2kHz PULSE. LASER SOURCE DEVICE Figure 3. Laser Source Device Page 5 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 2.3.2 Power Meter Figure 4 shows a Power Meter with the major functions noted. INDICATION OF WAVELENGTH TO RECEIVE INDICATION OF MEASUREMENT dBm OR W. AREA FOR POWER/LOSS MEASUREMENT EITHER dBm FOR LOSS TESTING OR W FOR POWER LEVEL MEASUREMENTS. SET WAVELENGTH 850NM OR 1300NM FOR MULTIMODE AND 1310NM OR1550NM FOR SINGLEMODE. PRESS AND HOLD TO SET REFERENCE VALUE OF TEST SET-UP. REFERENCE LOSS VALUE WILL TRANSFER TO UPPER RIGHT CORNER OF DISPLAY. POWER METER Figure 4. Power Meter Page 6 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 2.3.3 Test Set-Up to Obtain Reference Value In Figure 5 the laser source is on and set for 1550nm (green LED). The power meter is set to receive 1550nm. The reference button is pushed and held until the loss value is set as reference. ONE JUMPER LASER SOURCE POWER METER Figure 5. Test Set-Up (One Jumper) Page 7 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 In Figure 6 a second jumper is placed in the link to check the reference and set-up. At a wavelength of 1550nm the resulting 0.05dB reading on the meter matches the 0.057dB given in the manufacturer’s data. TEST JUMPER #2 TEST JUMPER #1 Figure 6. Check Reference and Set-Up Before proceeding with the test, obtain a copy of the work order or a knowledge of the end customer’s specifications or goals. You also need to fully understand the test methodology and procedures. The Power Meter/Laser Source, Testing and Troubleshooting flow chart does not supersede the test equipment manufacturer’s recommended test procedures. The flow chart is intended as a troubleshooting guide not an acceptance test plan. Note: Always clean all connectors including both ends of the patch cords and the “rear” connector on the panel in question before starting any testing or troubleshooting. Page 8 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 POWER METER/LASER SOURCE, TESTING AND TROUBLESHOOTING PREPARATION WORK Equipment Inventory Work Order or Goals Training and Understanding POWER METER AND LASER SOURCE INITIATION AND VERIFICATION Operate per Manufacturer’s Instructions Adjust to Desired Settings Verify Proper Operation PATCH CORD VERIFICATION Connectors are rated up to 500 matings – manufacturer reconnectorization and test acceptance is required beyond the recommended matings. NO POWER METER OPERATING PROPERLY AND CALIBRATED YES NO CONDUCT QUICK CHECK OF REFERENCE VALUE Place an additional patch cord (or jumper) between the Laser Source and Power Meter. Measure the loss versus the previous reference value. The loss should be as expected for one connector (typically less than 0.5 dB loss). CONDUCT TEST AND MEASUREMENT OF CABLE PLANT Connect Laser source and Test Jumper #1 to input of cable plant. Connect Power Meter and Test Jumper #2 to output of cable plant. Measure cable plant losses. LASER SOURCE AND PATCH CORDS OPERATING PROPERLY AND CALIBRATED YES YES ESTABLISH EXPECTED VALUE OR MAXIMUM OPTICAL LOSS ACCEPTABLE Is the loss value under the expected or specified loss for the cable plant? NO End of procedure – ensure all reports, notifications, and follow-up are completed. Calculate the sum of all cable plant losses. ESTABLISH REFERENCE For network troubleshooting the power meter testing will be performed in manual modes rather than automatic features. Adjust settings to typical or to the end customer specifications. Clean ALL connectors and inspect for clean end-faces. Determine loss test method. Connect cleaned patch cords according to test method selected. Set laser source to 1550nm Continuous Wave (CW). Conduct test initialization and establish the reference loss value. Clean all connectors accessible and affected by test set-up; Test Jumper #1 connector at cable plant input adapter. Jumper or patch cord of cable plant input adapter. Test Jumper #2 connector at cable plant output adapter. Jumper or patch cord of cable plant output adapter. Redo the test for cable plant loss. Continued on next page. Page 9 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 POWER METER/LASER SOURCE, TESTING AND TROUBLESHOOTING (continued) End of procedure – ensure all reports, notifications, and follow-up are completed. YES NO YES Is the loss value under the expected or specified loss for the cable plant? Is the loss value under the expected or specified loss for the cable plant? NO An excessive loss is an indication of a micro or macro bend, faulty connection, poor splice, or bad cable attenuation. If available use an OTDR or return loss meter to help further locate areas of higher loss. A visible light source should be used to see if there are indications of broken fiber, incorrect splice, or bend radius violations. If visible light “leaks out”, indicating a source of excessive loss, that area will need to be corrected. For example, splice a broken fiber or re-splice a bad splice. Re-route any cable with improper bend radius. Conduct test at 130nm and 1550nm, if 1550nm loss value is markedly higher than the 1310nm test, this is an indication of bend violations. With the Laser off visually inspect the end-face of all accessible connectors. Poor end-face characteristics may yield higher insertion losses. Repolish or reconnectorize the fiber if needed. Test smaller segments of the cable plant until the high loss area is isolated. Page 10 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 2.4 Power Meter Test and Troubleshoot – Expected Loss and Optical Budget Calculations Each part of the cable plant design will add attenuation or optical loss. The total loss based on assumptions will yield the expected loss value. A cable plant loss budget can be derived by different methods. It can simply be the sum of maximum loss values as given in industry standards. It can be the minimum receiver sensitivity minus the minimum transmitter output. Or it can be the value given for link power budget from the specified signal protocol's accepted standard. Maximum connector losses are given for a mated pair connection and are specified by the manufacturer. Specified values range from 0.3dB to 0.75dB and depend on whether the connection is multimode or singlemode. Most manufacturers are able to guarantee maximum values at 0.5dB and this value will be used to calculate loss budgets. Maximum values for cable attenuation are given by the cable manufacturer, and are typically as follows: • • • • 3.5dB/km Multimode at 850 nm (3.0dB/km typical) 1.5dB/km Multimode at 1300 nm (1.0dB/km typical) 1.0dB/km Singlemode at 1310 nm (0.4dB/km typical) 1.0dB/km Singlemode at 1550 nm (0.3dB/km typical) Excessive cable attenuation is a function of the cable manufacture and not the end connectors or splicing. Splice loss will vary based on performance of the equipment and the operator. For loss budget calculations in this document fusion type splices will be 0dB and mechanical splices will be 0.2dB. In the cable plant shown in Figure 7 there are four mated pair connections, two splices (assumed to be heat shrink fusion), and approximately 5km of cable. We can assume that the cable length of jumpers and pigtails is insignificant. TX Max. Output = 0dBm TX Min. Output = –7.0dBm 5km TX RX Max. Input Sensitivity = 0dBm RX Min. Input Sensitivity = –30.0dBm RX MATED PAIR CONNECTION WITH A MAXIMUM 0.5dB INSERTION LOSS OR ATTENUATION MECHANICAL SPLICE WITH A MAXIMUM OF 0.2dB INSERTION LOSS OR FUSION SPLICE OF 0dB INSERTION LOSS. CABLE ATTENUATION IS BASED ON LENGTH AND TYPE. FOR MOST SINGLEMODE CALCULATIONS USE 1.0dB/km. Figure 7. Sample Optical Budget Calculation Page 11 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 To calculate maximum expected loss for the system, each loss is given a value and the sum taken. (4*0.5dB) + (2*0.0dB) + (5km*1.0dB/km) = 7dB total loss. The cable plant loss budget can be specified as a value less than the expected total loss or it can be derived from the transmitter and receiver values. For example, using the values given for the transmitter and the receiver. Take the minimum sensitivity of the receiver and subtract the minimum output of the transmitter. –30.0dBm – (–7.0dBm) = –23dB Hence, theoretically there could be an optical loss of 23dB to the original signal and the receiver should just be able to receive the signal. This document does not include other factors such as power penalties established in certain standards. All loss factors should be included and understood in the loss budget calculation. 2.5 Testing with Power Meter and Laser Source Warning: Invisible infrared radiation can seriously damage the retina of your eye. Do not look into the launching (output) end of an active fiber. A clean, protective cap or hood MUST be immediately placed over any radiating bulkhead receptacle or optical connector to avoid exposure to potentially dangerous amounts of radiation. This practice also helps to prevent contamination of connectors and adapters. There are three methods given in TIA/EIA-526-14A, Optical Power Loss Measurements of Installed Multimode Fiber Cable Plant, for testing a cable, connection, or span. Similarly, there are three methods outlined in TIA/EIA-526-7, Measurement of Optical Power Loss of Installed Single-Mode Fiber Cable Plant. For singlemode fiber the three TIA/EIA-526-7 methods are listed as A.1, A.2, and A.3. For multimode fiber using TIA/EIA-526-14A the three methods are listed as A, B, and C. It is important to note that method A.1 is the same set-up as method B. The three methods are different based on the manner in which the base reference value is determined. Or put another way, the methods are different in what link section is “zeroed out”. There are several applications in which the Power Meter and Laser Source are used to test. • • • • Fiber link loss or span loss testing Component insertion loss testing Transmitter power level measurements Fiber identification and continuity Page 12 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 In Figure 8 the Power Meter will measure the transmitted power PTX less any link losses. It can also be said that the Power Meter is measuring the link or cable plant “insertion loss”. LINK LOSSES DUE TO CONNECTORS, SPLICES, AND CABLE ATTENUATION TX ADAPTER POWER METER RX SPLICE TRAY AND SPLICE Figure 8. Transmitter Power Level Measurement The following procedures show the three methods to obtain a test set-up reference value. In all cases the test jumper connectors and cable must be of a high enough quality to continue the assumption of negligible effects. It will be assumed that upon obtaining the reference value, and connecting the test jumpers to the cable plant under test, that test fiber jumper losses due to length and connection are negligible. The final test measurement will be the same for all methods. The Laser Source will supply a light wavelength through a test jumper to the cable plant under test. On the other end of the cable plant is a second test jumper to a Power Meter set to measure the same wavelength. The Power Meter can be set to measure power levels in dBm (deciBels as referenced to milliwatt power) or, more typical, set to measure the loss measured in dB as compared to a reference set-up value. Figure 9 shows the test set-up used for the testing methods for singlemode fiber as outlined in TIA/EIA-526-7, Measurement of Optical Power Loss of Installed Single-Mode Fiber Cable Plant. CABLE PLANT UNDER TEST TEST JUMPER 1 TX TEST JUMPER 2 PWR MTR LSR SRC RX Figure 9. Cable Plant Test Set-Up Page 13 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 Figure 10 shows the manner in which the test reference value is obtained using one test jumper. The set-up will reference or zero the system to just the connectors at the Laser Source and Power Meter interfaces. Hence when the test is conducted with two jumpers, the entire cable plant including jumper connections are included. METHOD A.1 ONE JUMPER METHOD PWR MTR LSR SRC Figure 10. A.1 One Jumper Test Method The test measurement is then conducted with two jumpers, see Figure 11. The test process will be the same, differing in what connections are measured or zeroed out. TEST JUMPER 1 TEST JUMPER 2 CABLE PLANT LSR SRC TEST INCLUDES TEST JUMPER CONNECTIONS AND CABLE PLANT – REVEALS SYSTEM “INSERTION LOSS”. Figure 11. Cable Plant Test with Jumpers (A.1) Page 14 © 2009, ADC Telecommunications, Inc. PWR MTR ADCP-90-388 • Issue 1 • 2/2009 Figure 12 shows the manner in which the test reference value is obtained using two test jumpers. The set-up will reference or zero the system to the connectors at the Laser Source and Power Meter interfaces, as well as one full connection. Hence when the test is conducted with two jumpers, the resulting loss should not include the source and meter interfaces and one additional connection. It can be assumed that the two test jumpers connected will have the same loss characteristics and quality of any cable plant connection. It is with this assumption that one connection is removed from the final loss value. The one connector is either from the source to the cable plant or from the cable plant to the meter. METHOD A.2 TWO JUMPER METHOD LSR SRC PWR MTR Figure 12. A.2 Two Jumper Test Method The test measurement is then conducted with two jumpers, see Figure 13. The test process will be the same, differing in what connections are measured or zeroed out. TEST JUMPER 1 TEST JUMPER 2 CABLE PLANT LSR SRC TEST INCLUDES ONE TEST JUMPER CONNECTIONS AND CABLE PLANT – REVEALS LOSS BEYOND PATCH PORT. PWR MTR Figure 13. Cable Plant Test with Jumpers (A.2) Page 15 © 2009, ADC Telecommunications, Inc. ADCP-90-388 • Issue 1 • 2/2009 Figure 14 shows the manner in which the test reference value is obtained using three test jumpers. The set-up will reference or zero the system to the connectors at the Laser Source and Power Meter interfaces, as well as two full connections. Hence when the test is conducted with two jumpers, the resulting loss should not include the source and meter interfaces and two additional connections. It can be assumed that the two test jumpers connected will have the same loss characteristics and quality of any cable plant connections. It is with this assumption that two connections are removed from the final loss value. The two connectors are assumed to be the patch panel interfaces from the source to the cable plant and from the cable plant to the meter. METHOD A.3 THREE JUMPER METHOD OR REFERENCE JUMPER METHOD LSR SRC PWR MTR Figure 14. Three or Reference Jumper Test Method (A.3) The test measurement is then conducted with two jumpers, see Figure 15. The test process will be the same, differing in what connections are measured or zeroed out. TEST JUMPER 1 TEST JUMPER 2 CABLE PLANT LSR SRC TEST INCLUDES CABLE PLANT ONLY – REVEALS SPAN OR LINK LOSS, INCLUDING PATCH PANEL PORTS. Figure 15. Cable Plant Test with Jumpers Page 16 © 2009, ADC Telecommunications, Inc. PWR MTR ADCP-90-388 • Issue 1 • 2/2009 3 CUSTOMER INFORMATION AND ASSISTANCE PHONE: U.S.A. or CANADA Sales: 1-800-366-3891 Extension 73000 Technical Assistance: 1-800-366-3891 Connectivity Extension: 73475 Wireless Extension: 73476 EUROPE Sales Administration: +32-2-712-65 00 Technical Assistance: +32-2-712-65 42 EUROPEAN TOLL FREE NUMBERS Germany: 0180 2232923 UK: 0800 960236 Spain: 900 983291 France: 0800 914032 Italy: 0800 782374 ASIA/PACIFIC Sales Administration: +65-6294-9948 Technical Assistance: +65-6393-0739 ELSEWHERE Sales Administration: +1-952-917-3000 Technical Assistance: +1-952-917-3475 13944-Q WRITE: ADC Telecommunications (S’PORE) PTE, LTD; 100 Beach Road, #18-01, Shaw Towers. Singapore 189702. ADC Telecommunications, INC PO Box 1101, Minneapolis, MN 55440-1101, USA ADC European Customer Service, INC Belgicastraat 2, 1930 Zaventem, Belguim PRODUCT INFORMATION AND TECHNICAL ASSISTANCE: [email protected] [email protected] [email protected] [email protected] REPRINTS: PDF copies of manuals are available for downloading at the following link: www.adc.com/manuals ADCP Number: 90-388 Contents herein are current as of the date of publication. ADC reserves the right to change the contents without prior notice. In no event shall ADC be liable for any damages resulting from loss of data, loss of use, or loss of profits and ADC further disclaims any and all liability for indirect, incidental, special, consequential or other similar damages. This disclaimer of liability applies to all products, publications and services during and after the warranty period. Page 17 © 2009, ADC Telecommunications, Inc.