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Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to "Ask SILICON CHIP" and "Circuit Notebook".

Solar effectiveness is regional

A number of readers have commented that I appear to have condemned electric cars in my article "How to Reduce Your Greenhouse Gas Emissions, Pt.3" (SILICON CHIP, September 2007). Electric cars are quite advantageous in countries or regions where the electricity produced generates less than about 0.9kg of CO2 per kWh. Victoria averages about 1.4kg/kWh and the Australian average is about 1.0kg/kWh.

In the USA, the average is about 0.7kg/kWh, so electric cars would be better there than petrol. For Australia at present, gas-powered cars may be the best option since, apart from being relatively low in CO2 emissions, they reduce our dependency on foreign oil.

In the case of solar hot water heating, there are several factors which determine whether a booster is required and what sort of booster is appropriate. To give some examples: if you live in Victoria, with high CO2 per kWh and your solar system supplies only 60% of the energy, then a gas booster is appropriate. In Tasmania, most of the electricity is hydro and so even though the solar fraction is lower, electricity produces the lowest greenhouse gas emissions.

If you live in the sunnier areas of Australia, where the solar fraction can be very high or 100%, again electricity may be the best. So essentially the decision is based on solar insolation (how sunny your location is), your usage level and the "dirtiness" of the electricity supply you would use to heat the water.

Peter Seligman,

Essendon, Vic.

Australia on the right wavelength with digital radio

I wish to comment on the letter concerning DAB+ in the September 2007 issue of SILICON CHIP. It’s a shame a letter writer has attacked Australia’s plans for digital radio without the facts and without being prepared to put their name to their opinion.

Commercial radio broadcasters have every confidence that Australia can successfully lead the way with digital radio. We have a long history of innovation that has seen radio adapt and flourish over the years despite the advent of technologies such as TV, CD players and the internet. The development of portable and in-car listening, the introduction of top 40 music formats, talkback radio, pioneering live news and sports reports from the scene, interactivity, streaming online and radio podcasts are examples of the way radio has continually evolved both its content and distribution over the years. Digital radio is the next step.

The decision to go with DAB+ was not driven by "bureaucracy" but by radio stations who understand what listeners want. DAB+ technology allows us to offer exciting new features and a multitude of content that just isn’t possible with AM and FM.

We should be proud that Australia was the first country in the world to switch on a high power DAB+ test - but we are far from alone. Trials have been conducted in Italy, Czech Republic and France, while many other countries including Canada, Hungary, Israel, Kuwait, Malaysia, Malta, New Zealand and China are making preparations for trials and launches. DAB+ is our opportunity to move the industry forward and those who don’t embrace this change will most likely be left behind. If our anonymous critic would like to come out from behind the cloak of anonymity then we can make sure he or she is acquainted with the facts of digital radio, both here and globally, and will thus be equipped to make, in the future, an informed comment.

Joan Warner,

Chief Executive Officer,

Commercial Radio Australia.

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