Just what is broadband

Dan Warne
21 October, 2007
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I bet, as an AMW reader and your friends’ and family’s tech advisor, you’ve had the question at least 10 times in the past few years: which broadband’s the best type? Unless you’re a tech enthusiast, it’s perfectly normal not to carry round a catalogue of line speeds for different types of broadband in your head.

Chances are, though, that as an AMW reader, you are broadly aware that cable has traditionally offered around 10Mbps, Telstra’s ADSL was limited to 1.5Mbps for most of the past decade (though the top speed was recently unlocked to 8Mbps) and that the newer ADSL2+ providers including Internode, iiNet, Optus and others, offer speeds of 24Mbps. (That’s megabits per second, not to be confused with megabytes per second.)

And you may be aware that the wireless broadband plans offered by the mobile networks using HSDPA allow you to get anywhere from a quarter of a megabit to couple of megabits a second. But regardless of which network you’re actually hooked up to, are you really getting the speed you expected?

The Australian Competition and Consumer Commission (ACCC), which regulates truth in advertising, has been on a campaign to get broadband providers to tell the complete truth about the speeds customers can expect to get.

I know from my own informal contact with several major ADSL2+ ISPs that this has royally peeved them — not because they’re unhappy about being made to publish their statistics on how many customers get what speed, but because they believe there are far more important things for the ACCC to be doing, like actually fining Telstra for its anti-competitive monopolist conduct, rather than letting the telco giant off with a slap on the wrist each time.

However, I think the ACCC has a point. The ISPs have been spruiking ADSL2+ that offers “up to 24Mbps” speed, when the vast majority of people are not going to get anything like that kind of speed. For example, I was on Telstra ADSL1 at home, getting 8Mbps downstream and a piddling 384Kbps upstream. Although the downstream speed was reasonable, I really wanted faster upstream so I could use the online backup service mozy.com more effectively. So I upgraded to iiNet’s ADSL2+ service, expecting a decent speed boost in both directions.

After paying the changeover fee to iiNet and suffering through a week of being offline while Telstra got its act together and unplugged me from one box and into another at the exchange, I got a surprising speed result.

I did get the boost in upstream speed that I wanted — up to the full 1Mbps that the ADSL2+ standard is capable of — but, unbelievably, my downstream speed actually dropped a little bit, to 7.6Mbps. By fiddling with the settings in my iiNet profile (choosing a line profile with a less conservative signal-to-noise ratio) I was eventually able to get the line speed up to 9Mbps, but it was nowhere near the “24Mbps” figure you hear bandied round for ADSL2+.

The truth is, ADSL2+ line speed drops off very quickly the further you get from an exchange. One AMW reader, Miklos Somogyi, wrote in recently to express his disappointment at finding himself in the same situation as me: his ADSL2+ connection was only firing up at 8Mbps, despite being only about 1.5km from the exchange.

The reality is that Telstra’s century-old copper twisted-pair network was never designed to carry high speed broadband signals. It’s a miracle that ADSL2+ works as well as it does, given the mix of different thicknesses of copper wire in the network and bits of wire hanging loose off homeowners’ phone lines (known in the telco industry as ‘bridge taps’, which is just a fancy word for when that physical line was once connected to someone else’s house and the telco couldn’t be bothered removing the wire lead-in to the house).

The variable speeds obtained on ADSL2+ (see the table below, based on data supplied by Internode) do show why a fibre-optic network is important for Australia. Fibre signals do not degrade — and that’s why fibre is used for submarine cable runs of thousands of kilometres under the sea. By bringing the fibre close to people’s homes, the ADSL2+ signal (or VDSL2) can travel over existing copper phone lines into people’s houses with good results.

I do wish the ACCC would extend its scrutiny on speed claims to other areas of the technology industry. 12-hour notebook battery life — has anyone ever achieved that? 54Mbps wireless throughput on 802.11g — a fairytale. At least Apple seems to be reasonably honest with its marketing claims.

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