Fiber optic cable should be checked in three stages:

Stage 1: Receiving the supply.

  - Locating manufacturing defects.

  - Location of defects caused by transport.

Stage 2: Making the connection.

  - Locating installation defects.

  - Locating defects in the assembly of connectors in the field.

  - Locating defects in the fiber optic splicing process.

Stage 3: Acceptance trial.

  - Network certification.

  - Compliance with service specifications.

 

8.1 Visual Inspection

  graphic inspection- Microscopes (inspection of wiring in the field and workshop). Procedure:

  • Clean the surface to be inspected.
  • Select the adapter type on the microscope.
  • Adjust the focus.
  • Check status.

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graphic recovery - Fiber identifier.

  • Identify the arrangement of the optical fiber.
  • Locating splices in boxes.
  • Location of fiber optic breaks in cords and cables.
  • Optical continuity tester.

 

 

 

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8.2 Optical power measurement

  • Adapters for bare fiber (fiber optic cable connection).
  • Power meter (Appropriate wavelength selector).
  • Emission source (LED or laser suitable for the wavelength).

power measurement graph

 

 

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  - Procedure

  • Start-up of the equipment (for its stability).
  • Select wavelength on both devices.
  • Calibrate the equipment using patch cords and an adapter.
  • Set to "0 dBr" or note the power value (dB) of the source.
  • Connect cord "A" to the adapter of the section to be checked.
  • Connect cord "B" to the adapter of the section to be checked.
  • Record the value obtained, repeat the procedure, or with the rest.

graph source meter

 

 

 

 

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- Measurements in laces and measurements in lines.

graphicalmeasurementscordsgraph of measurements and lines 

 

 

 

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8.3 Backscatter Measurement (OTDR)

Optical reflectometer with time domain basis, sending short pulses of light to determine characteristics (length, losses, etc.).

  • Suitable wavelength λ.
  • Proper wiring.
  • Sufficient dynamic range (depending on wavelength).
  • Use of the dead zone eliminator (launch fiber).
OTDR graphics  - PROCEDURE
  • Equipment startup (for its stability).
  • Select wavelength λ.
  • Checking the dynamic range for the total measurement of events.
  • Connect the launch fiber to the equipment (200-500 meters for MM / 1000 meters for SM).
  • Perform first sweep to determine launch fiber.
  • Enter identification parameters and measurements (λ, IR (refractive index), length, origin, end, etc.).
  • Perform the first measurement on an optical fiber of the cable or section to be measured.
  • Using the first one as a reference, perform the rest of the measurements.
  • Analyze events and determine the end of the segment.
  • Perform the same operation in the opposite direction.

  - EVENTS

    a) Dead zone.

    b) Reflection (Fresnel):

  • Change in refractive index (connections, mechanical splices, etc.).
  • No reflection appears in APC type connections.
  • Erroneous gain.

    c) Splice losses:

  • Fiber splice.
  • Defective radius of curvature.

     d) Final fiber reflection:

  • Optical length.
  • Return losses (light returning to the emitter).
     e) Attenuation value per section.

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graphic verificationgraficotecverif2