FOA CFOS/DAS key terms

The total allowable optical power loss between a transmitter and receiver, calculated as transmit power minus receiver sensitivity minus safety margin. It caps the sum of fiber attenuation, splice loss, connector loss, and passive component loss.

The loss per unit length of fiber, usually stated in dB/km at a specified wavelength. It drives the fiber contribution to a link loss budget and differs by wavelength and fiber type.

The minimum optical power at which a receiver meets its bit-error-rate specification. It sets the lower bound of the power range the receiver can accept and directly affects the link loss budget.

Extra decibels reserved in a loss budget for aging of components, temperature effects, repairs, additional splices, and measurement uncertainty. It is subtracted before comparing available loss to estimated loss.

A band of wavelengths used for transmission, such as 850 nm, 1310 nm, or 1550 nm. Each window has its own attenuation and dispersion behavior and influences fiber and transceiver selection.

Pulse spreading caused by different wavelengths traveling at different speeds in fiber. It limits reach and bit rate on single-mode links and is a design check alongside loss budget.

Pulse spreading caused by different polarization states traveling at slightly different speeds, mainly in single-mode fiber. It becomes significant at very high bit rates and long distances.

The ratio of reflected power to incident power at a component or link, expressed in decibels. Poor return loss destabilizes lasers and degrades performance, so it is specified for connectors and splices.

The portion of light reflected backward at an interface such as a connector end face. High reflectance can disturb laser operation and is controlled by polishing, angled contacts, and good cleaning.

Optical power lost at each mated connector pair, typically a fraction of a decibel. Designers budget a per-connector allowance and count connector pairs along the link path.

Optical power lost at a fusion or mechanical splice, usually small and expressed in decibels per splice. Designers multiply an allowance by the number of splices in the link.

Test instruments used together to measure end-to-end loss of a fiber link. The source injects a known wavelength and the meter reads received power, allowing loss calculation by comparison with reference.

The loss a component adds when inserted into a link, measured as the drop in received power. It is the standard way to characterize connectors, splitters, and other passive devices.

The division of input power among output ports of a passive splitter, such as 1:8 or 1:32. Higher split ratios increase loss and reduce the power available to each subscriber.

A point-to-multipoint fiber architecture using unpowered splitters between a central office and subscribers. Its loss budget must account for splitter loss, feeder, distribution, and drop segments.

Choosing how many fibers a cable carries, including spare capacity for growth and repairs. It considers current demand, expected take rates, splice closures, and future upgrade paths.

Providing physically separate cable paths so a single incident cannot cut all service. It affects design cost and is required for critical circuits and some network tiers.

All fiber facilities installed outdoors, including aerial, buried, and underground cable, closures, pedestals, and handholes. Design must address environment, access, and protection.

Work required on utility poles or conduit before new cable can be installed, such as moving attachments, replacing poles, or clearing ducts. It is a major schedule and cost risk in outside plant projects.

Formal approval from a landowner or authority to place facilities, such as a right-of-way or road-crossing permit. Permit lead time often controls the project schedule.

The legal corridor in which a utility may install and maintain cable, granted by a property owner or government. Acquiring and documenting it precedes construction.

A written description of what the project will and will not deliver, including boundaries, assumptions, and acceptance criteria. It prevents misunderstanding and anchors change control.

A hierarchical decomposition of project work into manageable deliverables and tasks. It supports estimating, scheduling, and assignment of responsibility.

The longest sequence of dependent tasks through a project schedule. Any delay on this path delays the project finish, so it receives the closest monitoring.

The amount of time a task can slip without delaying the project finish or a successor. Tasks with zero float are on the critical path.

The approved version of the project schedule used to compare actual progress against plan. Changes to it require formal approval through change control.

A formal process for evaluating, approving, and documenting changes to scope, schedule, or cost. It protects the baseline and records why deviations occurred.

Reserve time or money held for known risks that may occur. It differs from management reserve, which covers unknown risks and is typically controlled above the project manager.

A log of identified risks with likelihood, impact, owner, and response plan. It is reviewed regularly and drives contingency planning.

A document inviting vendors or contractors to bid on defined work, stating requirements, evaluation criteria, and contract terms. It supports competitive selection and comparable offers.

An itemized list of all materials and components needed for the project, with quantities and specifications. It links design to procurement and to cost estimating.

A forecast of project cost built from quantities, labor rates, material prices, and allowances. Accuracy improves as design matures from conceptual to detailed.

Structured tests, such as loss and length measurement, performed to confirm the installed link meets specification before handover. Results are documented and compared with design values.

Records of the final installed configuration, including routes, fiber assignments, splice schematics, and test results. It supports operations, troubleshooting, and future design.

Techniques such as dispersion-compensating fiber or modules used to offset chromatic dispersion so longer or faster links work reliably. It is applied where dispersion, not loss, limits reach.

The documented plan of which fiber in which cable serves which circuit or subscriber, including splice tray positions. Good mapping reduces errors during splicing and future changes.