Fiber optic cable is a transmission medium with minimal drawbacks: it is more expensive than copper alternatives, requires specialized tools for termination, and demands a certain level of skill or training to handle properly. However, the benefits are significant:

• High bandwidth: Capable of transporting much more data than conventional copper cables.
• Low signal loss: Light signals travel farther with minimal attenuation.
• Immunity to electromagnetic interference (EMI): Fiber does not conduct electricity, making it impervious to external electrical noise.

Fiber Operating Modes and Attenuation

The maximum transmission distance over fiber depends on wavelength and mode (multimode or single-mode). Approximate attenuation at different wavelengths, per kilometer of fiber, is shown below:

In the USA, single-mode fiber is commonly used for long runs (miles of distance), while multimode is more typical for shorter LAN backbones (a few hundred meters or less).

Types of Fiber Optic Cable

By fiber material:

• GOF (Glass Optic Fiber) – the most common, especially for long distances.
• POF (Plastic Optic Fiber) – used mainly for short-range consumer or industrial applications.

By installation environment:

• Outdoor: Can be direct-buried in the ground, deployed aerially on poles, or submersed. Often armored or specially protected against moisture and rodent damage.
• Indoor: Fire-rated jackets (OFNR, OFNP) for risers or plenum spaces.

By installation conditions:

• Aerial cables (with Kevlar or support strands).
• High-voltage line attachments (with lightning protection).
• Armored for direct burial (steel wire or corrugated steel tape).
• Underwater (multi-layer construction).

SFP Modules (Mini-GBIC)

A typical method to connect fiber to Ethernet equipment is via SFP (Small Form-Factor Pluggable) transceivers. Each SFP acts as a transmitter/receiver pair, handling digital data over fiber at specified speeds (100 Mb, 1 Gb, 10 Gb, etc.). Newer standards like SFP+ cater to 10 Gb/s and beyond.

Fiber connectors commonly used with SFPs:

• LC – small form factor
• SC – larger push-pull connector
• FC – threaded, robust against vibration

Optical Budget

An optical budget is the difference (in dB) between the transmitter’s optical power and the receiver’s sensitivity threshold. In specifications, it is expressed in dBm (decibels relative to 1 mW). It must exceed the sum of all losses in the fiber path (including connectors, splices, etc.). For instance:

• Determine minimum transmitter power (e.g., –1 dBm).
• Determine receiver sensitivity (e.g., –22 dBm).
• Optical budget = (–1 dBm) – (–22 dBm) = 21 dB.
• Subtract total link losses (e.g., 4 dB) → final margin is 17 dB.

If the final margin is positive, the link should function properly. For common SFP distances:

Common Connector Types

• FC: Uses a threaded coupler, excellent for single-mode in high-vibration or harsh environments.
• SC: Push-pull connector, widely used in both multimode and single-mode.
• LC: Smaller, high-density push-pull connector with a 1.25 mm ferrule.

Color coding: Single-mode SC connectors are often blue; multimode connectors are typically beige or gray. LC connectors may also follow a similar convention, though color codes vary among manufacturers.

FIBER CONNECTOR INSTALLATION TECHNOLOGIES

• Epoxy Crimp Polish: The most traditional, reliable method used in factory production of patch cords (“pigtails”). The fiber is glued inside the connector ferrule with epoxy, then polished.
• Hot Melt: Similar to epoxy but uses a factory-loaded adhesive (compound).
• Light Crimp: A purely mechanical fix; no adhesives or heat required, making it quick but potentially less robust.
• Pre-Loaded Fiber (field-terminated “fusion” or mechanical splice): The connector ferrule has a pre-installed short fiber stub. The installer cleaves the field fiber, aligns/splices to the stub, and a matching gel or mechanical clamp ensures minimal loss.

Pigtails, Patch Cords, and Splices

• Patch cord: A fiber cable (often duplex) with connectors on both ends.
• Pigtail: A short fiber cable pre-terminated on one end only.
• Mechanical Splice (e.g., Fibrlok™): Allows splicing two fiber ends without fusion welding. Typical insertion loss ~0.1 dB.

From Fiber to Copper (Media Converters)

When transitioning from optical fiber to twisted-pair Ethernet (Cat 5e/Cat 6), a media converter is used. The installer must:

• Terminate the fiber in a patch panel, closure, or wall mount enclosure.
• Use patch cords to connect the fiber panel to the media converter’s SFP or fiber input.
• Use an RJ-45 patch cable from the media converter’s Ethernet port to the switch or camera.

Typical Rack Setup

• Fiber cable with factory or field-terminated connectors.
• Fiber patch panel or wall mount enclosure (aka “fiber enclosure” or “optical cross”).
• Fiber patch cords (often duplex) connecting the panel to the media converter or switch SFP.
• Media converter (if the switch does not have an SFP port).
• RJ-45 patch cable to the switch port or camera.

ISO/IEC 11801:2002(E) guidelines address polarity marking (A/B) on duplex adapters, ensuring transmit (Tx) goes to receive (Rx).

FIBER EXTENSION EXAMPLES

You can extend network signals over long distances (up to miles/kilometers) for IP cameras by using fiber transceivers or industrial switches with fiber ports.

Example:

• Figure 53: Up to 2 km connecting 4 IP cameras to an NVR via a single fiber trunk (using a multi-port media converter or fiber-capable switch at the camera end).
• Figure 54: A single remote IP camera up to 2 km from the NVR over fiber.

If coax is preferred or already in place, there are also coax extenders that allow IP signals over existing RG-59 or RG-6 for distances of 1,200 to 1,800 m (~3,900 to 5,900 ft) under certain conditions.