1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.Copyright 2003 SAE InternationalAll rights reserved. No part of this publication may be
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4、-776-0790Email: custsvcsae.orgSAE WEB ADDRESS: http:/www.sae.orgAEROSPACE RECOMMENDED PRACTICEARP5061Issued 2003-05Guidelines for Testing and Support of Aerospace, Fiber Optic, Inter-Connect SystemsTABLE OF CONTENTS1. SCOPE .22. APPLICABLE DOCUMENTS23. DEFINITIONS.33.1 General Fiber Optic Terms.33.2
5、 Fiber Optic Cable Plant Topology 93.3 Fiber Optic Testing and Equipment124. GENERAL REQUIREMENTS.204.1 Cable Plant Husbandry204.2 Troubleshooting .214.3 Test Equipment 224.4 Optical Launch Conditions.284.5 Fiber Optic Connector Cleaning 404.6 Link Loss Test Procedures.414.7 Safety.435. NOTES .45APP
6、ENDIX A FIBER OPTIC SUPPORT EQUIPMENT.46APPENDIX B AEROSPACE PLATFORM INTERCONNECTS82SAE ARP5061 - 2 -1. SCOPE:1.1 Scope:This ARP document will provide guidelines for optical performance testing of short haul fiber optic inter-connection systems used in aerospace vehicles. The focus of this document
7、 is to establish common pre and post installation test methods and troubleshooting methodologies.1.2 Applicability:This document establishes guidelines applicable to test fiber media which includes fiber optic cables, connectors (simplex, multi pin, ribbon), couplers, splices, optical switches and m
8、any other passive and active elements affecting optical power distribution through inter-connect hardware. Where there is conflict between this document and the air vehicle specification or contract, the air vehicle specification or contract shall take precedence. Where design is such that the metho
9、ds herein cannot be implemented, users will submit relevant information or modifications to existing methods to the specified sponsor of this document for review.2. APPLICABLE DOCUMENTS:2.1 Government Documents:2.2 Specifications and Standards:The following specifications and standards form part of
10、this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and supplement thereto, cited in the solicitation.2.2.1 Specifications:MIL-PRF-29504, Term
11、iniMIL-PRF-85045, Cable2.2.2 Standards: Not Applicable2.3 Other Government Documents:The following other Government documents form a part of this standard to the extent specified herein. Unless otherwise specified, the issue of those cited in the solicitation.Not ApplicableSAE ARP5061 - 3 -2.4 Non-G
12、overnment Documents:TIA/EIA-455, Fiber Optic Test ProceduresAIR 5271, ComponentsANSI Z136.2, American National Standard for the Safe Use of Lasers2.5 Order of Precedence:In the event of a conflict between the text of this standard and the references cited herein, the text of this standard shall take
13、 precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exception has been obtained.3. DEFINITIONS:3.1 General Fiber Optic Terms:ABSORPTION: Loss of light in a fiber caused by intrinsic impurities, resulting from conversion of optical power into h
14、eat energy.ACCEPTANCE CONE: The cone containing incident rays that couple into bound modes of the fiber. The half angle is equal to the acceptance angle.ADD-DROP MULTIPLEXER (ADM): A component used to multiplex lower-speed electrical and/or optical signals into a high-speed optical channel. Supports
15、 time division multiplexing (TDM) or dense wavelength-division multiplexing (DWDM).AMPLIFIED SPONTANEOUS EMISSION (ASE): The light emitted from the decay of the upper level of a lasing transition without stimulated emission. (Broad spectral emission and unpolarized.)AMPLITUDE MODULATION (AM): Transm
16、ission technique where the information is encoded in the amplitude of the carrier.ASYNCHRONOUS TRANSFER MODE (ATM): A high-speed transmission scheme providing bandwidth on demand for multimedia (data, voice, video).ATTENUATION: The diminution of average optical power. Attenuation results from absorp
17、tion, scattering, and other radiation losses. Attenuation in general is expressed in dB without a negative sign.ATTENUATOR: An optical device that reduces the intensity of a light beam passing through it.AVALANCHE PHOTODIODE (APD): A photodiode that produces current through internal amplification. (
18、Avalanche multiplication)BACK REFLECTION OTDR: Back reflection is the return of part of the energy in the launched pulse to the OTDR by an event along the fiber. Also known as Fresnel reflection.SAE ARP5061 - 4 -3.1 (Continued):BACKSCATTERING OTDR: Back scattering is the portion of returned energy t
19、hat returns in a generally opposite direction to that of the launched pulse to the OTDR by microscopic imperfections along the fiber. Also known as Rayleigh backscattering. For example, the back-scattered signal from a 1-inch length of 100/140 micron multimode fiber at 850 nm wavelength is approxima
20、tely -60 dB.BANDWIDTH: Measure of information carrying capacity; the greater the bandwidth, the greater the information carrying capacity.BEND LOSS: The result of macrobends (curvature of fiber) or microbends (small distortions in the fiber) producing increased attenuation by coupling light energy f
21、rom the fiber core to the cladding.BIREFRINGENCE: The property whereby the effective propagation speed of a light wave in a medium depends upon the orientation of the electric field (state of polarization) of the light.BIT-ERROR-RATE(BER): The number of digital highs on a transmission link that are
22、interpreted as lows, and vice versa, divided by the total number of bits received. (BER should be better than 1x10-9in properly operating systems.)BOUND MODES: In a multimode fiber, the power in bound modes is predominately contained in the core of the fiber.BUFFER COATING: Protective material that
23、covers and protects a fiber. (No optical function.)CALIBRATED LAUNCH CABLE OTDR: Is a serial numbered special jumper, serving to interconnect the OTDR with the aircraft harness connector for testing the harness. The launch terminus may be a pin or socket. The integrity and cleanliness of the launch
24、terminus is checked by the OTDR on both Fresnel and Rayleigh operating modes according to the serial number, prior to launch terminus insertion.CENTRAL WAVELENGTH: Wavelength of a sources peak power.CHIRP: A change in the characteristic optical frequency of a device as a function of time (modulated
25、diode laser) or position (chirped fiber Bragg grating).CHROMATIC DISPERSION: A phenomenon caused by the wavelength dependence of group velocity in an optical fiber. Since any practical light source has a certain spectral width, chromatic dispersion results in pulse broadening. The coefficient descri
26、bing chromatic dispersion per unit length is generally given in units of ps/(nm_km).CLADDING: That dielectric material of low refractive index surrounding an optical fiber core that has a lower refractive index than that of the fiber core.CLADDING BOUNDARY: Consisting of the inner and outer limits o
27、f the layer directly surrounding the core.SAE ARP5061 - 5 -3.1 (Continued):CLADDING LIGHT: Light propagating in the cladding.CLADDING MODES: A mode in which the electromagnetic field is confined in the cladding and the core by virtue of these being a lower refractive index medium surrounding the out
28、ermost cladding.COHERENCE: A phenomenon whereby the phases of the photons (or constituent wave trains) of a light beam maintain a definite relationship with each other. A narrow line-width laser is said to exhibit a high degree of coherence.CONNECTOR: Hardware installed on cable ends to connect cabl
29、es to a device or another cable.CONTINUOUS WAVE(CW): Constant output from an optical source that is active but not modulated by a signal (DC).CORE: The central region of an optical fiber with higher refractive index than that of the cladding, within which most of the optical power is to be transmitt
30、ed.CORE CENTER: For a cross section of an optical fiber, it is the center of that circle which best fits the outer most limit of the core area.CORE DIAMETER: The diameter of the circle defining the core center.CUTOFF WAVELENGTH: The shortest wavelength for which an optical fiber can only support the
31、 propagation of a single transverse mode.dB: Decibel. Standard logarithmic unit for the ratio of two quantities. In fiber optics, the ratio is optical power and represents loss or gain.DEADZONE OTDR: The distance from an event, such as a connector, over which the OTDR signal is saturated and the OTD
32、R is not able to make measurements.DISTANCE ACCURACY OTDR: The difference between the true distance in a fiber and the OTDR measurements value, using the true value of the effective group index of the fiber.EFFECTIVE GROUP INDEX OTDR: The effective group index of a fiber is the ratio of the pulse pr
33、opagation speed in vacuum and in the fiber. The value for glass fiber is approximately 1.5.EQUILIBRIUM MODE DISTRIBUTION: The condition in a multimode optical fiber in which relative power distribution among the bound modes is independent of length.EVENT OTDR: An abrupt discontinuity or index change
34、 in the fiber, such as a connector, a mechanical splice, a star coupler, a break, etc. A cleaved fiber end or a flat polished open connector back reflects approximately 4% (or -14dB) of the incident pulse energy. A break in a 100/140-micron multimode fiber back reflects from -30 to -14dB.SAE ARP5061
35、 - 6 -3.1 (Continued):FAR FIELD REGION: The region at some distance from a source or aperture where the radiation pattern is independent of the distance. The far field is generally characterized by an angular distribution of light intensity.FIBER OPTIC CABLE: Any installed jacketed optical fiber.FIB
36、ER OPTIC SYSTEM: The assembly of all the interconnected fiber optic subsystems, including sources, detectors, cables, couplers and connectors.FRESNEL MODE OTDR: A low sensitivity operating mode of the OTDR for the detection of gap type connectors, reflective mechanical splices, reflective couplers a
37、nd switches, fiber breaks and cracks, and for the measurements of length, distance, back reflection and return loss. The approximate sensitivity range for the Fresnel operating mode is -10 to -40 dB (relative to a -14 dB cleaved end). Also, refer to OTDR Trace - Fresnel. GAP TYPE CONNECTOR: The mate
38、d pair has an air gap between the glass end faces. The gap may range from less than one, to several microns. The gap can result from polishing connectors to a predetermined length as in SMA style connectors, or from having a concave polish or under cut profile on one or both endfaces of the mating f
39、iber in multi-contact terminus style connectors. Gap type connectors are classified as “loud” reflective connectors - OTDR.GRADED INDEXED FIBER: An optical fiber having an index profile in which the refractive index varies continuously as a function of radial distance from the longitudinal axis of t
40、he fiber.INSERTION LOSS: The logarithm of the fraction of received power/transmitted power through a component in the link multiplied by 10. The insertion loss of a mated pair of connectors transmitting 90% of the incident energy is 0.46 dB. A coupling transmitting 50% energy has an insertion loss o
41、f 3.0 dB.LAUNCH CONDITIONS OTDR: Accurate and repeatable loss measurements in short haul, large core fiber, with concatenated connectors, require a special beam profile of the OTDR probe pulse.LARGE CORE FIBER: Large core fiber is considered fiber with a nominal core diameter greater than 62.5 micro
42、ns.LOUD: A component, such as a connector, is referred to be “loud”, if its return loss is less than approximately 30 dB.LOSS ACCURACY OTDR: The difference between the true insertion or return loss of a single isolated event and the OTDR measurements value, using the true value of a reference reflec
43、tor.MAP AND TEST OPERATION OTDR: Is a operating mode that enables the maintainer to auto-test each fiber optic link in the air vehicle against a previously created map of the same, and identify changes or faults in the link.SAE ARP5061 - 7 -3.1 (Continued):MAXIMUM THEORETICAL NUMERICAL APERTURE: A t
44、heoretical value of numerical aperture calculated using the values of refractive index of the core and cladding is given by:(Eq. 1)where:n1= maximum refractive index of the coren2= refractive index of the innermost homogeneous claddingMODE: A mode of an axially uniform waveguide describes an optical
45、 field distribution whose amplitude in a plane normal to the fiber axis does not vary with axial distance along the waveguide, other than for the effects of a uniform attenuation.MULTI-MODE FIBER: An optical fiber, which can support one or more bound modes in addition to the fundamental mode.NEAR FI
46、ELD REGION: The region close to the source, or aperture where the radiation pattern is dependent on the distance from the source, along the source axis. The near field is generally characterized by a spatial distribution of light intensity.NUMERICAL APERTURE: The sine of the vertex angle of the larg
47、est cone of meridianal rays that can enter or leave an optical fiber system or element, multiplied by the refractive index of the medium in which the vertex of the cone is located.OTDR: Optical Time Domain Reflectometer. Also referred to as an Optical Fiber Monitor (OFM). Utilizes pulses of light in
48、jected into the fiber and analyzes the reflected return light to determine the distance down a fiber a reflection (connector, break, etc.) was encountered.OTDR TRACE - FRESNEL: In the Fresnel mode of operation, the trace consists of a flat baseline at the zero intensity level, and individual pulses
49、extending from the baseline, representing loud events. This trace may be stylized by replacing the pulses with artificial symbols, such as sticks, for easier interpretation.OTDR TRACE - RALEIGH: In the Fresnel mode of operation, the trace consists of a staircase shaped elevated baseline, and individual pulses extending from the baseline, usually at the edge of each step, representing quiet events. The insertion loss of an event is proportional to the vertical distance of the steps on either side of the event. The trace may be stylized for easi
