How Does Fibre Broadband Work So Fast?

spectrum, rainbow, prism, light, fibre, full fibre, fibre broadbandIf you remember your physics from school you’ll know that electricity travels at the speed of light, and that the speed of light is a constant (provided it’s travelling through a medium which isn’t incredibly dense, or incredibly cold, or a black hole… OK in NORMAL circumstances light speed is a constant!), so if electricity can travel down a wire that fast, how does fibre, which uses light instead of electricity, transmit so much more data?


It’s not as if Full Fibre is a little bit faster than copper wire either. Depending on how far you are from the internet exchange you’re using you could get speeds of up to 80 Mbps on copper cable. If you happened to live 100 metres or less from the servers. Go to 200 metres and your speed could drop to 65 Mbps, and it would get slower and slower the further you kept going without the introduction of repeaters, boosters and other devices that keep the signal strong and fast.

As well as resistance in the cable meaning that the useful quality of data reaching your computer at any given moment is less than when it was sent, there’s a limit to the amount of data which can physically be sent down the wire. In the days of dial-up you couldn’t share the phone line at all. If someone in your house was online the phone would be engaged for the duration. Digital Subscriber Line (DSL) was invented so you could make a call and use the internet at the same time. Asymmetric Digital Subscriber Line (ADSL) divides up the frequencies which are available on a copper wire and uses them to send more data, but the number of frequencies available are limited. And it still slows down the further you are from the servers.

Fun With Full Fibre Frequencies

Fibre optic cable doesn’t work this way at all. First of all, the length of any single piece of cable can be many times that of a copper wire before it needs any intervention from boosters or repeaters.

Second of all, and more importantly, the number of frequencies which are available down a thread which is narrower than a human hair far exceeds those available in a wire. This is because white light isn’t. White light appears to be white, but it’s made up of all the colours visible to the human eye. White light can be split into all these component colours through the use of a prism. Remember, digital technology works by data being converted into a signal being either off or on. Via fibre this simply means flashing the light incredibly fast. So if you send the data needed to stream a movie in red light that means flashing red, but all the other colours of the spectrum are doing nothing. So why not send the data needed to download a record in green light? And browse Facebook and Instagram in violet?

All The Colours Of The Rainbow

Now, we talk about seven distinct colours in the spectrum, but there are many gradients of colour as red moves into orange then onto yellow and green, blue indigo and violet. Use sensors in the fibre router which can pick up the difference and separate them out means that there are many, many more channels available down a single fibre optic filament than can be contained in a wire cable.

But fibre isn’t perfect. Back to physics again! If light entering the fibre isn’t perfectly aligned internal refection in the filament means that the light can’t leave, but over a great distance the light which travels a zig-zag path takes longer to reach its destination then light which travels smoothly. Because of this delay the signal which reaches the end user isn’t perfectly crisp and clear, a factor which then has to be compensated for. But yet the technology still remains hundreds of times faster than the copper alternative.

Fibre In The Future

Being able to send all this data down a single thin, lightweight, flexible medium to homes and businesses in Sussex has other benefits too. It’s futureproof for the foreseeable future. While people invented ADSL for the old phone lines, people will be inventing other things for fibre optic to make it go even faster without needing to upgrade the line that comes into your house or business premises.

Copper is heavy, bulky, delicate, and has an intrinsic value on the commodities market. That last point means that it’s not only extremely expensive to buy and install, it is tempting to thieves. In July this year people were left without internet or landline phone use in Maidstone, Kent when thieves stole a cable serving 8000 users. Conveniently glass fibre, even the extremely high clarity glass needed in fibre optics is very lightweight compared to an equal length of copper cable, and is worthless on the resale market, meaning there is no incentive to steal it out of the ground.

Briant Broadband are the only genuinely local Worthing based internet provider with a range of flexible packages which offer a number of different packages to suit any need or budget.

Visit Briant Broadband, email us for more information or call 01903 221999

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