The process of turning off the analogue television signal in Wales begins
More than 130,000 homes are poised to become the first in Wales to begin the permanent switch to digital television.
The process of turning off traditional analogue TV signals for Swansea and Neath Port Talbot begins at midnight.
It means that viewers who do not have digital will not be able to see BBC Two from Wednesday, and then they will lose all channels within a month.
The rest of Wales will follow later this year and early next year, with every home going digital by March 2010.
Digital UK said 90% of homes in Wales already had digital TV and were able to receive around 40 channels, rather than four or five on analogue.
Emyr Byron Hughes, regional manager for Digital UK in Wales, said: "The UK is going digital, the US has already gone digital, some European countries as well.
"It's all about more choice and better use of the available frequencies but mostly about choice."
DIGITAL SWITCHOVER, 2009-2010
Transmitter: Kilvey Hill; area served: Swansea, Neath Port Talbot area: 12 Aug - 9 Sept 2009
Preseli; south west Wales: 19 Aug - 16 Sept
Carmel; parts of south and central Wales: 26 Aug - 23 Sept
Llanddona; north west Wales: 21 Oct -18 Nov
Moel y Parc; north east Wales: 28 Oct -25 Nov
Long Mountain; parts of east and central Wales: 4 Nov - 3 Dec
Blaenplwyf; parts of west and central Wales: 10 Feb - 10 March 2010
Wenvoe; Cardiff, Newport and south east Wales: 3 - 31 March
Source: Digital UK
The latest figures from Digital UK suggest 95% of people in south Wales are aware of the switchover and 76% of people know what to do.
Analogue viewers have also been reminded with on-screen captions about the need to convert.
The first stage of the switchover will see BBC Two cease broadcasting in analogue and the first group of Freeview digital channels becoming available.
Four weeks later, the remaining analogue channels will be permanently switched off and replaced with additional digital services.
After the Kilvey Hill transmitter, the next to switch will be Preseli, covering south west Wales, on 19 August followed by others throughout the year and early 2010.
The last in Wales will be Wenvoe, serving Cardiff, Newport and south east Wales, on 3 March with the whole process completed by April.
Wales will be the first nation in the UK to go completely digital.
But Consumer Focus Wales has previously warned of potential confusion leading to people being overcharged when changing.
Spokesman Gareth Price said: "Most people won't need new equipment beyond a digital Freeview box on top of their TV. But if you do, get more than one quote, compare prices and use a reputable trader."
Older and disabled people are able to use a special scheme to help them make the switch.
Gareth Earle, regional project co-ordinator for the Switchover Help Scheme, said: "People are eligible if they're aged 75 or over, if they're on certain disability benefits, if they're blind or partially sighted, or if they have lived in a care home for six months or more.
"Everyone who is eligible will be contacted by us and the standard option for most people will be £40."
Kitty Phillips from Neath said older people such as herself relied on television and would be lost without it.
"It helps people of my age and it helps people who are very lonely," she said.
"It brings life into the home when I can't get out. I couldn't be without it if I tried. I love my TV, I always have.
"I enjoy every programme and I practically watch it from morning until night."
The Digital UK helpline is 08456 50 50 50 (08458 48 48 48 for Welsh speakers).
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