The BBC is celebrating the first birthday of its HD channel. Although trialled throughout 2006, the channel didn't officially launch until 7 December 2007 when it was given approval for go-ahead by the BBC Trust.

Now the channel broadcasts between 6.20pm and midnight with extended hours at weekends and for live events that are in HD. This will increase over Christmas and to nine hours a day during 2009.

On the service's anniversary, Danielle Nagler, head of BBC HD, BBC Vision has acknowledged its "teething pains" that have included disappearing sound, lip synch issues and probs with picture quality but says "BBC HD is still only a toddler and there's a fair amount of maturing to do".

In a blog post about the "birthday" Nagler says: "I hope that over the next year we will be able to offer more stable delivery and a richer mix of programming on the channel so that whatever your personal passions there is always something that you can find to engage with".