Fibre Specification Standards User Manual The most important thing we build is trust Cobham Wireless - Coverage
Table of Contents 1. Single-mode Fibre to ITU-T Recommendation G.652 3 2. SC/APC Mated Pair Requirements 3 3. Single-Mode Fibre Requirements 4 4. Fibre Connector End face Inspection Zones and Grading. 5 4.1. Fibre Inspection Acceptance Criteria 5 Page 2 of 6
1. Single-mode Fibre to ITU-T Recommendation G.652 For optimal performance and ease of commissioning, Cobham Wireless recommends that the fibre optic link between the Optical Master and the remote repeater comprises of a single fibre run with fusion splicing of fibre to ensure optimal reflectance of the link performance. The fibre link must use Single mode fibre which meets the requirements of ITU-T Recommendation G.652.D. All fibre connectors must be APC type with SC/APC interfaces to the Cobham Wireless equipment and be certified compliant to IEC-61300-3-35 APC specifications The use of optical patch panels to join adjacent lengths of fibre can lead to performance degradation and failure of inter equipment communication. Should alternative methods of fibre cable joining be used, they must meet the requirements of the table below: Fibre Link Specification Fibre Type Fibre Connectors Optical Loss Transition Reflectance Number of APC connections Requirement 9/125um G625.D SC/APC (8º Angled Physical Contact) 10dBo maximum > 60 db 6 maximum (including equipment interface) Please make the necessary measurements to ensure a correct installation of the fibre distribution system. When the fibre cable has been installed, the quality of the optical path should be checked for optical path loss over the entire length and the magnitude and location of any reflections. Prior to any commissioning and support activity, Cobham Wireless requires Optical Time Domain Reflectometer (OTDR) measurement of each optical link in both directions across the operating optical wavelengths. Ensure that the OTDR pulse width is applicable to the measurement distance to ensure accurate results. Notes: Keep all discrete reflections to > 60 db. The SC/APC connectors specified are polished to a return loss > 60 db. 2. SC/APC Mated Pair Requirements Mated Pair SC/APC Specification APC Angle Optical Loss (Typical) Optical Loss (Maximum) Transition Reflectance Requirement 8º Angled Physical Contact 0.15dBo 0.35dBo > 60 db NB / Fusion Splice required = 0.1dBo Page 3 of 6
3. Single-Mode Fibre Requirements Throughout this manual, important safety warnings and admonishments are included to warn of possible hazards to persons or equipment. A safety warning identifies a possible hazard and then describes what may happen if the hazard is not avoided. The safety warnings in the form of Dangers, Warnings and Cautions must be followed at all times. These warnings are flagged by the use of a warning icon, usually the triangular alert icon seen below. The exclamation point within the triangular alert icon is intended to warn the operator or service personnel of operation and maintenance from factors relating to the product and its operating environment, which could pose a safety hazard. Applicable Standards and Norms: ITU-T Recommendations G.652.D IEC/EN60793-2-50 cat B.1.3 IEC-61300-3-35 The following details summarise the main Optical, Geometrical and Physical Characteristics of fibres, compliant to the above standards. Fibres are manufactured from high grade silica, doped as necessary to achieve the required light guiding properties, designed with a matched-cladding, step-index profile. The fibre coating is a dual layer structure of ultra-violet cured acrylate resin. The lower modulus inner layer being optimised for both adhesion to the fibre surface and mechanical stripping using the appropriate stripping tools. The outer layer is optimised for abrasion resistance and fibre processing properties. Certain Cobham Wireless products require a wide range of optical frequencies for WDM operation, the optical fibre must be suitable for operation at the following wavelengths: 1310 1370nm and 1490 1590nm. Attenuation Requirements Wavelength Typical Attenuation Maximum Units Attenuation 1310-1390 nm 0.33 @ 1310nm 0.40 max db/km 1490-1590 nm 0.25 @ 1550nm 0.30 max db/km Other Requirements Fibre Property Value Coating diameter 235 to 255 nm Coating diameter coloured 250 ± 15 nm Coating concentricity error 10 μm Coating non circularity 6% Mode Field Diameter @ 1310 nm 8.6 to 9.5 μm Cladding diameter 125.0 ± 1.0 μm MFD/cladding concentricity error 0.6 μm Cladding non-circularity error 1.0 % Cable cut-off wavelength (method A) 1260 nm Attenuation at 1383 nm 0.40 db/km Attenuation uniformity < 0.1dB/km at 1310 nm and 1550 nm Point discontinuity < 0.1dB at 1310 nm and 1550 nm Dispersion 1285 1330 3.5 ps/nm.km Dispersion 1550 18.0 ps/nm.km Zero Dispersion Wavelength 1300 to 1324 nm Zero Dispersion Slope S0 0.092 ps/(nm2.km) Polarisation mode dispersion 0.06 ps/ km (link value) Proof test 1.0% Strain equivalent 100 turns x 60mm diameter < 0.05 db at 1550 nm Page 4 of 6
4. Fibre Connector End face Inspection Zones and Grading Inspection zones are a series of concentric circles that identify areas of interest on the connector end face. The inner-most zones are more sensitive to contamination than the outer zones. It is common to divide the image into a series of concentric circles that begin with a small one centered on the core (also known as zone A ) and then radiate out from there. This creates a bulls-eye pattern sometimes called a grading overlay. The overlay is used to GRADE the fibre by determining the number and size of each particle that are present in each of the 4 fiber zones Figure 1 Fiber End face Inspection Zones for Single-Fibre Connection 4.1 Fibre Inspection Acceptance Criteria Acceptance Criteria are a series of failure thresholds that define defect limits for each zone on the fibre connector end face. All loose particles must be removed. If defect(s) are non-removable, it must be within the criteria specified below to be acceptable for use. The tables below list the Acceptance Criteria standardized by the International Electro technical Commission (IEC) for single-mode and multi-fiber single mode connectors as documented in IEC 61300-3-35 Ed. 1.0. All fibre connectors shall be inspected and a PASS Certification report should be produced to prove compliancy with these criteria before being deployed in the network. Single-Mode APC Connectors: IEC 61300-3-35 Page 5 of 6
Single-Mode (APC) Zone Name (Diameter) Scratches Defects A Core Zone (0-25µm) 4< 3µm None B Cladding Zone (25-120µm) No limit No limit <2 µm 5 from 2-5 µm None >5 µm C Adhesive Zone No limit No limit (120-130µm) D Contact Zone (130-250µm) No limit None =>10 µm All loose particles must be removed. If defect(s) are non-removable, it must be within the criteria above to be acceptable for use. For scratches the requirements refer to width. No visible surface cracks are allowed on the core or cladding zone. There are no requirements for the area outside the contact zone since defects in this area have no influence on optical performance. Cleaning loose debris beyond this section is recommended good practice. The limit for non-linear non-removable features in the ferrule/contact zone (D) does not apply for metal-alloy ferruled connectors. Page 6 of 6