FOA CFOS/L flashcards
FOA CFOS/L · Build recall with a focused review session.
31 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Total internal reflection
- The confinement of light in the core when it strikes the core-cladding boundary above the critical angle; requires the core refractive index to exceed the cladding index.
- Numerical aperture
- A measure of a fiber's light-gathering ability, computed as the square root of n_core squared minus n_cladding squared; it equals the sine of the maximum acceptance angle.
- Graded-index multimode
- Multimode fiber whose core refractive index decreases gradually toward the cladding, reducing modal dispersion and raising bandwidth compared with step-index multimode.
- Attenuation formula
- Loss in decibels equals ten times the base-10 logarithm of input power divided by output power; fiber attenuation is normally stated in dB per kilometer.
- Single-mode core size
- Single-mode fiber uses a core of roughly 8 to 10 micrometers inside a 125-micrometer cladding, allowing only one propagation mode at the operating wavelengths.
- Horizontal cabling limit
- The permanent horizontal cable run from the telecommunications room to the work area is limited to 90 meters within a 100-meter channel that includes patch cords.
- Plenum-rated cable
- Cable with low-smoke, low-flame-spread jacket materials, marked CMP or OFNP, permitted in air-handling spaces where smoke propagation must be minimized.
- APC versus UPC polish
- APC connectors use an 8-degree angled ferrule with better return loss than flat UPC; the two polish types must never be mated because of high loss and damage risk.
- LC connector
- A small-form-factor fiber connector with a 1.25-millimeter ferrule and a push-pull latch, commonly used for high-density patch panels and equipment ports.
- MPO connector
- A multi-fiber push-on connector holding 8 to 24 fibers in a single ferrule, used for parallel optics and high-density backbone or data center links.
- OM3 and OM4 fiber
- Laser-optimized 50-micrometer multimode fiber types; OM4 has higher bandwidth and supports longer 10-gigabit distances than OM3.
- Tight-buffered cable
- Indoor fiber cable construction with a protective buffer applied directly to each fiber, allowing direct field connectorization and flexible routing inside buildings.
- Fiber color code order
- The standard 12-fiber sequence is blue, orange, green, brown, slate, white, red, black, yellow, violet, rose, and aqua, repeated with tracers for higher counts.
- Pull tension limit
- The maximum force allowed on cable during installation, set by the manufacturer; tight-buffered indoor fiber is commonly limited to about 25 pounds-force.
- Bend radius rule
- Cable must not be bent tighter than about 20 times its diameter during installation or 10 times its diameter after installation, per manufacturer and standard requirements.
- Service loop
- Extra cable slack of at least one meter left at each end and in enclosures so the cable can be reterminated or rerouted without pulling a new run.
- Firestopping
- A listed system that restores the fire rating of a floor or wall where cable penetrates it; required at every rated penetration and recorded in documentation.
- Cable labeling
- Unique identifiers applied to both ends of every cable and to individual fiber strands before pulling, matched to the cable schedule and as-built records.
- Tier 1 testing
- Fiber testing with a light source and power meter to measure insertion loss and length; it confirms that a link meets its loss budget.
- Tier 2 testing
- Tier 1 testing plus an optical time-domain reflectometer trace that locates splices, connectors, and faults along the fiber for detailed analysis.
- Reference method
- The one-, two-, or three-jumper setup used to zero the test equipment before measuring; it determines whether connector loss is included in results.
- End-face inspection
- Examining every connector with a magnification scope before mating to detect contamination, scratches, or pits that cause loss and permanent damage.
- Loss budget formula
- Total allowed loss equals fiber attenuation times length plus splice losses plus connector losses plus a margin, commonly three decibels for aging and future repairs.
- OTDR launch cable
- A known-length fiber (typically 100 meters or more) attached before the fiber under test so the near-end connector and first events can be measured accurately.
- Insertion loss
- The reduction in optical power caused by a component such as a connector or splice, measured in decibels as the difference between input and output power.
- Channel length model
- The 100-meter channel consists of 90 meters of horizontal cable plus up to 5 meters at the work area and 5 meters in the telecommunications room.
- 10GBASE-SR distance
- A 10-gigabit multimode standard reaching about 300 meters on OM3 and 400 meters on OM4 fiber at 850 nanometers.
- 10GBASE-LR distance
- A 10-gigabit single-mode standard operating at 1310 nanometers and supporting links up to 10 kilometers on OS2 fiber.
- As-built documentation
- Closeout records including cable schedules, strand assignments, rack elevations, test reports, and firestop records that reflect the installed cable plant.
- Change control
- A written process requiring approval and an updated drawing before any deviation from the design, such as altered routing, connector type, or fiber count.
- Site survey
- A pre-design walkthrough recording distances, pathways, access, power, and obstructions so the cabling design and bill of materials reflect actual conditions.