Michael Foreman: Radiation limits achilles heel of the videophone

I must confess to harbouring a guilty little secret. It's very embarrassing I know, but until recently I believed that if I was armed with a next generation mobile phone connected to a so-called 2.5G network, I would very soon be able to download data at a rapid rate.

Not only had I fondly imagined that 2.5G networks would provide mobile internet access at near broadband speeds, but I even entertained daydreams of downloading MP3 songs or short video clips to my cellphone.

But the sad truth is that at launch, both the Telecom CDMA (Code Division Multiple Access) network and Vodafone GPRS (General Packet Radio Services) will crawl along at less than dialup modem speed.

Once you get past the hype about sending digital photos or videos to friends at Telecom's website, you'll find on a subsequent page that the CDMA one technology being launched mid-year offers a maximum data speed of 14.4 kilobits per second, a quarter of dialup speed. Even worse, if you read the small print you'll find that this speed, a snail's pace by landline standards, is theoretical - the actual speed achieved under real world conditions may be degraded by the number of voice and data users in your base station area.

Telecom says it will upgrade to the faster CDMA 2000 1X standard by the end of this year, which offers a more respectable maximum speed of 144 kbps. But once again this is theoretical and what the website does not tell you is that you'll have to ditch your months-old CDMA one handset to take advantage of the faster speeds.

Questions also hang over Vodafone's GPRS network, in place since December but not yet commercially launched.

According to Vodafone, the delay is because of a lack of handsets. Motorola is the only manufacturer that has provided it with GPRS phones and the launch has now been pushed back until April or May.

Visit Vodafone's site and you'll see that last April, the company was boasting its GPRS network would provide increased bandwidth of 115 kbps that will enable the faster delivery of more feature-rich content to handsets, such as videoconferencing.

But Vodafone has since changed its tune. Now the company is saying that GPRS will be suitable for bursty type applications such as e-mail and will offer data transfer speeds of up to 115 kbps.

When we asked Vodafone exactly how fast "up to" meant we were told to expect data transfer speeds of 20 kbps. That's a big drop from the earlier claims, so we wondered whether it had anything to do with a report last year by New Scientist that Motorola had been forced to limit the speed of its GPRS phones to avoid overheating and radiation emission problems.

According to New Scientist the GSM system over which GPRS runs uses channels sliced into eight slots. On a GSM network, each slot is allotted to a different phone and carries data at 9.6 kbps, but GPRS lets users harness more than one available slot.

While you could theoretically bunch together four or five slots for GPRS reception, handsets may overheat if they transmit on more than one slot, causing circuits to burn out. Above two slots, the phone's microwave radiation could exceed European (and New Zealand's) guidelines on the energy that can be absorbed by the brain.

Early GPRS phones will only use one transmission slot, with two slots for receiving. Later models will move to four reception slots, boosting download speeds, but they will stick with one transmission slot to stay within emission guidelines.

When the Herald mentioned this report and the dreaded radiation word in an article on February 27 we soon received a letter from Keith Anderson of Australian Mobile Telecommunications Association who wished to clarify some misconceptions in the article.

The full text of this letter may be read by follwing the link below but it includes a statement that there is no substantiated scientific evidence of any health risk from cellphone use and suggests we visit the World Health Organisation website.

For the record, we did not make any suggestion that there were health risks from cellphone use but, as AMTA has brought the subject up, a UK Government-commissioned report concluded a cautionary approach should be adopted.

Mr Anderson also wrote: "There is no sound basis to assert concern about the safety of these products or to suggest future phones may not meet the SAR (specific absorption of radiation) limits."

Once again we made no such suggestion, but I am beginning to wonder, if a manufacturer has to limit a 2.5G phones transmit speed to 9.6 kbps to stay within SAR limits, what price 3G?

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MOST USEFUL: Air NZ


If you haven't visited Air New Zealand's website for a while it's worth dropping in as it has long since departed from its beginnings as a clunky online brochure. The latest enhancement, which allows you to check your Air Points balance online, will be welcomed by business travellers. But what happened to online ticket purchasing?

Another minor gripe is that the ticker-tape style of the arrivals and departures page takes too long to read. Why can't the information be displayed all at once, like the signs at the airport?

Advisory: This site looks as if it'll get there eventually.

Links


Telecom CDMA Network

Vodafone GPRS network

Motorola

New Scientist

National Radiation Laboratory

Australian Mobile Telecommunications Association

Keith Anderson's letter: Cellphone industry says GPRS phones will be safe

World Health Organisation: Electromagnetic fields and public health

Independent Expert Group on Mobile Phones

Air NZ