Know your megabits from your FTTP

Helping you understand the complex world of broadband.


Firstly what is broadband?

Broadband is a high speed connection to the internet. Before broadband, internet access was achieved with ‘narrowband’ dial-up connections that were very slow by today’s standards. Broadband is much quicker and allows us to do more on the internet.

High speed data can be carried over a normal phone line without affecting the telephone service.


The term broadband simply means a broad band of frequencies has been used. It is a radio term and normally means that multiple frequency carriers are used to carry one signal. It describes the way ADSL (Asymmetric Digital Subscriber Line) services work so has become a term to describe a fast internet connection. The term is then being rather confusingly used to describe fibre connections which are not broadband at all, but use a single frequency laser.

Bits and bytes

Broadband speed is measured in bits per second (bps), which tells us the speed at which data is transferred. For home broadband this will be kilobits (Kbps or Kb), Megabits (Mbps or Mb) and Gigabits (Gbps or Gb).

Don’t get bits confused with bytes (Kilobytes, Megabytes, Gigabytes) as these terms denote memory capacity and file size, not speed. If there’s an upper case B (MB, etc) then it’s bytes.

There are eight bits in a byte, so, if your download speed is eight megabits per second (8Mb), then that’s actually shifting 1 megabyte per second (1MB).

It’s an important distinction, because file sizes (such as songs, pictures and movie clips) are described in bytes, as are download allowances. So to recap; its bits per second (b) when talking about broadband speed, and bytes (B) when talking about file sizes and download caps.

Download speed

When you connect to the internet, the download speed is the pace at which data (websites, programmes, music etc) is transferred from another source to your device.

Currently, when it comes to home broadband, advertised download speeds for nationwide providers typically range from 8Mb to 300Mb.

Upload speed

Upload speed is the speed data (such as your  photos and videos) is sent to the internet – perhaps to put onto a social networking site such as Facebook or to a photo printing website. Essentially, the upload is going in the opposite direction to the download – from your computer to someone else’s.

Broadband upload speeds are generally much slower than download speeds. The reason for this is that people generally do far more downloading than uploading, so downloading is given priority by the ISPs (who regulate how their networks deal with the various types of traffic).

Upload speeds are more important to people doing large amounts of uploading, such as someone who works from home and wants to exchange files with a remote network, or people who play a lot of online games – especially if they’re hosting.

How fast is my broadband connection?

The easiest way to find out how fast your broadband is is to do a  speed test. There are a variety of speed test sites available, though this speed test is simple and fast. All tests should be free.

There are a couple of things to note with a broadband speed test: before you do a test, make sure you have closed any other applications using the internet such as email and instant messaging programs. Secondly, your broadband speed can vary wildly at different times of the day depending on external factors, such as the number of users online in your building, your street, and even your country. Also, as more people are online, some
ISPs deliberately slow down lines in busy periods of the day – this is called ‘traffic
For these reasons, make sure you do a number of broadband speed tests at different times of the day – and on different days (weekdays, weekends etc) – to get a better picture of the kind of broadband speeds you are receiving.

The different ways broadband can be brought to you.

After dial up connections came DSL (Digital Subsciber Line)

DSL is a wireline transmission technology that transmits data faster over traditional copper telephone lines already installed to homes and businesses.  The availability and speed of your DSL service may depend on the distance from your home or business to the closest telephone company facility.

The following are types of DSL transmission technologies:

  • Asymmetrical Digital Subscriber Line (ADSL) – Used primarily by residential customers, who receive a lot of data but do not send much. ADSL typically provides faster speed in the downstream direction than the upstream direction. ADSL allows faster downstream data transmission over the same line used to provide voice service, without disrupting regular telephone calls on that line.
  • Symmetrical Digital Subscriber Line (SDSL) – Used typically by businesses for services such as video conferencing, which need significant bandwidth both upstream and downstream.


  • Fibre optic technology converts electrical signals carrying data to light and sends the light through transparent glass fibers about the diameter of a human hair. Fibre transmits data at speeds far exceeding current DSL typically by tens or even hundreds of Mbps.
  • The actual speed you experience will vary depending on a variety of factors, such as how close to your computer the service provider brings the fibre and how the service provider configures the service, including the amount of bandwidth used. The same fibre providing your broadband can also simultaneously deliver voice (VoIP) and video services, including video-on-demand.
  • Variations of the technology run the fibre all the way to the customer’s home or business, to the curb outside, or to a location somewhere between the provider’s facilities and the customer.
  • Fibre can go directly to the property and this is known as ‘Fibre to the Premise’ or FTTP, or only to a cabinet, known as FTTC (Fibre to the cabinet’).


  • Wireless broadband connects a home or business to the Internet using a radio link between the customer’s location and the service provider’s facility. Wireless broadband can be mobile or fixed.
  • Wireless technologies using longer-range directional equipment provide broadband service in remote or sparsely populated areas where DSL or cable modem service would be costly to provide. An external antenna is usually required.
  • Wireless broadband Internet access services offered over fixed networks allow consumers to access the Internet from a fixed point while stationary and often require a direct line-of-sight between the wireless transmitter and receiver.
  • Mobile wireless broadband services are also becoming available from mobile telephone service providers and others. These services are generally appropriate for highly-mobile customers and require a special PC card with a built in antenna that plugs into a user’s laptop computer.


  • Just as satellites orbiting the earth provide necessary links for telephone and television service, they can also provide links for broadband. Satellite broadband is another form of wireless broadband, and is also useful for serving remote or sparsely populated areas.
  • Downstream and upstream speeds for satellite broadband depend on several factors, including the provider and service package purchased, the consumer’s line of sight to the orbiting satellite, and the weather. Typically a consumer can expect to receive (download) at a speed of about 500 Kbps and send (upload) at a speed of about 80 Kbps. These speeds may be slower than DSL , but they are about 10 times faster than the download speed with dial-up Internet access. Service can be disrupted in extreme weather conditions.

What is an ISP?

An internet service provider (ISP) supplies the service and equipment to get your home or business online. Some ISPs operate their own infrastructure, but this is a complex and expensive endeavour so most pay for wholesale access to a network which they can then resell.


The CDS programme supports the broadband infrastructure and is to bring improved broadband to rural areas that would otherwise not be served commercially. The two broadband providers appointed to CDS operate as wholesale broadband providers and retail ISP’s.

COVID-19 Info

Whilst measures to contain COVID-19 continue to evolve, CDS will attempt to maintain a Business As Usual approach, though there may be some unavoidable impact on our ability to respond to queries.