Monday, 20 December 2010

DAB Radio

Just to make a change from Amateur Radio topics, this post is about domestic digital, DAB Radio.

Those of you listening to the BBC, in UK, can hardly have missed the adverts encouraging us all to rush out and buy a DAB radio for Christmas. There is of course a hidden agenda - the Government is just itching to grab back the FM broadcast band so it can sell it off. The have set a threshold of 50% of all households owning a DAB radio so they can name a date when FM transmissions can cease - even this very low criterion has not been met yet. These are my thoughts:
  • The UK Government have chosen the wrong system for DAB. They should have chosen the newer DAB Plus, which is used elsewhere in Europe. DAB and DAB Plus are not compatible so if they try to adopt DAB Plus, then all existing radios will be useless.
  • In my experience, DAB offers no better quality than FM, provided the signal strength is good.
  • DAB radios eat batteries so realistically have to be run from a mains power supply (My Sony XDR-S55 DAB radio is particularly bad, it runs off AA batteries and draws 200mA, which means about a 6-hour battery life. To make matters worse, this radio has an FM band but it continues to draw 200 mA even when switched to FM).
  • Most of the country, by area, either cannot receive any DAB signal or can only get a few stations. So it is not clear to me how DAB can be viable for car radios or those who live in remote areas. I did not find much evidence of a plan to improve this coverage rapidly.
  • Your DAB radio will not work abroad, apart from in a very few countries that use the UK system.

I do not want to be totally negative about DAB - there are some positives. If you live in a good signal area then you will get a lot more stations. Whether they are worth listening to is a matter for you! Some radios also give a text display, giving limited information about the programme you are listening to.

So should you ask Santa for a DAB radio in your stocking? If you are sure you live in a good signal area, you want the extra stations and you don't mind running the radio from the mains, then go ahead. BUT - do make sure your retailer will give you a refund if your radio does not receive the stations you expect - the coverage maps can sometimes be optimistic. You also need to be prepared for DAB to be phased out in favour of DAB Plus. This is not likely, in the short term, but you will almost certainly need to invest in a new radio if this happens.

I do not have any experience of DAB car radios, but I would be quite sceptical about their performance if you ever travel far from the large urban centres. Please post a reply if you use DAB in your car.

Monday, 13 December 2010

2m Club Championship December

For those not famililar with this two metre RSGB contest, it is run on the first Tuesday of each month. Points are per km for each QSO and multipliers are grid squares. Patricipants can add their scores to their club's total. The totals run from January to December for both individuals and clubs.

I have been working overseas a lot this year, but did get on for the December 2010 session. Conditions were quite flat, but as there were lots of stations participating I managed a reasonable claimed score of 11,000 +. I was pleased to work a station, M0GMG/A in IO83 - some 230 km away, which is not bad for 25 Watts and a 5-element beam in my loft.