Some useful terms as used on our web site. If you need more terms defining, please let us know.
- The term broadband was originally a technical term for a particular way of carrying signals using a broad band of modulated radio signal carriers. It sounds complicated, because it is. It is the way normal Internet access works over a telephone line after dial-up.
Over time, as it was the main way Internet access was provided it has gradually become synonymous with Internet access, even when that access uses something that is not actually broadband. In many cases on our web site we use broadband interchangeably with Internet access because of this modern common usage.
- The term fibre is short for fibre optic cable and relates to a particular type of cabling used to carry signals. It works by a glass fibre, with a second layer of glass around it, and this allows light to be shone down the glass for very long distances. It is used in the Internet in a lot of places to carry Internet traffic. It has a number of advantages allowing very fast data rates to be carried very long distance, as well as being immune to radio interference. It is used under the sea but also between data centres and nodes on the Internet.
When we refer to fibre we mean it. Some Internet providers have started referring to their service as being fibre optic broadband because some part of their network uses fibre optic cable for some of the connection even though part of it is copper (coax). When we say fibre to the cabinet (FTTC) we mean that an actual fibre optic cable is used between the exchange and a street cabinet. When we say fibre to the premises we mean there is fibre optic cable from the exchange to the premises.
- Fibre To The Cabinet describes the service where a fibre optic cable runs from the exchange to a cabinet, and then from the cabinet a VDSL service runs over copper phone wiring to the premises. The cabinet is actually two cabinets in this case, linked together, so that the phone line is jumpered to the second "fibre cabinet" which has the fibre link and VDSL modem/equipment. As cabinets are closer to the premises than the exchange this normally provides a better (faster) service than ADSL, though in rare cases VDSL can be slower than ADSL where there is a long run from the cabinet to the premises. Note that in some remote areas the connection from exchange to cabinet may actually be microwave and not fibre but providing the same services.
- Fibre To The Premises is where a fibre runs from the exchange all the way to the premises. This gives the better service as it has all of the advantages of fibre (immunity to electrical noise, joint corrosion, allows future upgrades to higher speeds, does not get slower with distance or neighbours getting service, etc).
- In some cases a service equivalent to FTTC is created using a microwave radio link to the cabinet instead of a fibre. This is the case in some rural communities where a fibre dig is too expensive. The services offered are essentially the same as FTTC in terms of speed.
- A modem is a modulator/demodulator. It is used to change one type of signal to another. A modulated signal is what is used on an ADSL/SDSL/VDSL line and means there are complex signals carried on the actual wires. What you need is ones and zeros to carry the Internet packets, and a modulators job is to convert between the two.
Typically a modem can be either a separate box, converting, for example, between VDSL and Ethernet, or could be a built in function in a modem/router device as a single box solution. You do not need to know much about modems other than the fact you have to have the right type for the service. Most ISPs supply modems, and we include suitable modems as standard or as an option in our various packages.
- A router is responsible for moving the various types of Internet packets between you network at home (may be many computers and devices) and the modem to the Internet. Often a single box will have a router and modem in one box, but they can be separate. Where they are separate they usually use a protocol called PPPoE (Point to Point protocol over Ethernet) and connect using an Ethernet cable.
- The term ADSL simple means a Line to a subscriber that carries Digital signals and is Asymmetric (i.e. different speeds each way). In practice it is used as a term for a specific set of standards for broadband (in the technical sense) communication over a phone line. ADSL1 and ADSL2 and ADSL2+ are various levels of these standards. The term ADSL is used for any services using these standards even if it happens that the speed each way is the same due to line conditions or configuration and so technically not asymmetric.
- The term SDSL simple means a Line to a subscriber that carries Digital signals and is Symmetric (i.e. same speed each way), so could be used to describe many services. In practice it is only used for a service using a specific set of broadband (in the technical sense) communication over a phone line which are designed to work at the same speed each way, typically quite low speeds by modern standards (500k, 1M, 2M). We no longer offer any of these SDSL services, and generally do not use SDSL to refer to other services that happen to be symmetrical.
- The term VDSL was stretching a point as the V stands for Very-High-Bit-Rate. It exists simply to differentiate it from slower ADSL, even though it is ADSL itself. It is used to refer to a specific set of broadband (in the technical sense) communication over a phone line which is normally used over shorter distances such as from a street cabinet to a premises. ADSL is usually used all of the way from the exchange to a premises. VDSL is the standard used for the last bit from the cabinet to the premises for FTTC services.