Explaining Fibre cables and connectors
Fibre can be a complex task when just getting started as there are many different standards available in the market. This article intends to explain some of the fundamentals of cable and connectors to aid you with choosing the right components and solutions for your fibre deployments.
The first decision you will need to make is your choice of cable. There are many different materials available to protect the sensitive fibre inside the sheath. Your choice will depend on whether you install indoors, outdoors, underground, aerial or underwater, each of these applications will require different types of cable composition. After selecting the cable structure, you need to consider the fibre core itself, as different types of technology are used to transmit and receive signals. Let’s explore some of the technology options available.
Multimode technology uses a short wave light source (850/1300nm) with a larger fibre core diameter. Due to its size, multiple paths (modes) are created and delivered separately, to the receiver connected at the other end. Unfortunately, it attenuates at a very high rate due to dispersion and therefore is not suitable for long distance (around 2km). On the positive side multimode is the most cost-effective fibre technology and very popular for uplinking switches or expanding your LAN over shorter distances.
Single mode technology uses a longer wave (1310/1550nm) over a much smaller core to only allow one mode of light. This minimizes the amount of attenuation of the light source and therefore is able to travel much longer distances (around 200km). Although more expensive than multi-mode it is ideal for WAN infrastructure and fibre to the home (FTTH) deployments.
There are a number of options available to connect the end of your cable to the light source. Usually, the connectors are dictated by the types of hardware at the deployment. LC connectors appear to be the most popular due to their economical design and small footprint.
The colour of the connector is also significant as to how light enters and leaves its source. A Polished Connector (PC) has around a -40db loss which is the equivalent to 0.01% reflected back to its source. They are typically used in multimode products and usually Beige, Black or Aqua depending on the type of cable.
Ultra Polished Connector (UPC) is Blue and uses the same mechanical design as PC but with an advanced polishing technique which reduces losses to around -55db. This connector type is designed for single mode and usually found on small form-factor pluggable modules (SFP). It is also compatible with regular PC connector types.
Angled Physical Contact (APC) is Green and polished at an 8 degree angle which reduces reflected light up to -60db which makes it ideal where radio signals are used over fibre. They are typically used in single mode Gigabit Passive Optical Networks (GPON) for FTTX. You should never connect APC to UPC/PC as you will experience major loss.
Getting the basics correct when it comes to cable and connectors is vital to achieving the best results on your fibre network.