What is the DTV transition?

The digital television transition (also called the digital switchover or analog switch-off) is the switchover from analog (the traditional method of transmitting television signals) to exclusively digital broadcasting of free television programming. The transition from analog to digital television represents the most significant advancement of television technology since color TV was introduced.

Countries that are already switched off to digital television are:

Luxembourg was the first country to complete the move to digital broadcasting on September 1, 2006.
The Netherlands moved to digital broadcasting on December 11, 2006. The switch-off was helped greatly by the fact that about 90% of the households have a cable that continues to use analog distribution.
Finland ceased analog terrestrial transmissions nationwide at 4 am, September 1, 2007 (switch-off was previously planned for midnight after August 31 but a few extra hours were added for technical reasons). Cable TV viewers continued to receive analog broadcasts until the end of February 2008.
Andorra completed its switch-off on September 25, 2007
Sweden The switch-off of the analog terrestrial network progressed region–by–region. It started on the island of Gotland on September 15, 2005, and was completed on October 15, 2007, when the last analog SVT1 transmitters in Scania and Blekinge were shut down. Cable distributors are allowed to continue broadcasting analog television.
Switzerland began with the switch-off on July 24, 2006, in Ticino and continued with Engadin on November 13, 2006. The switch-off was completed on 26 November 2007.
Austria began analog switch-off on March 5, 2007, progressing from the west to the east and finishing the switchover on May 5, 2008.

Countries that are currently in the process to switch-off to digital television are:

Australia: The Australian government originally planned a switch-off in 2008. This has now been delayed to 2009 for metro areas and to 2013 for the regions. Until that time, free-to-air stations will be simulcast, along with digital-only channels like ABC2. Since 1999, legislation has required all locally made free-to-air television transmissions to be in 16:9 widescreen format. Cable television networks began simulcasting in 2004 and analog cable services were switched off in April 2007.
Bulgaria will complete its analog switch-off in December 2012.
Brazil began free-to-air HD digital transmissions on, after a period of test broadcasts, on December 2, 2007, in São Paulo, expanding in January 2008 to Brasília, Rio de Janeiro, and Belo Horizonte. Digital broadcasts will be phased into the other 23 state capitals by the end of 2009, and to the remaining cities by December 31, 2013. Analogue and digital simulcasts will continue until June 29, 2016, when analog will be discontinued. The main broadcasters (Globo, Record, Band, SBT, and RedeTV!) are simulcasting in analog and digital broadcasts, in standard definition and 1080i high definition.
Belgium: the situation is rather complex, as media regulations are under regional legislation. The Flemish region has announced that it will switch off analog television on December 31, 2008, because coverage is already at 99 percent. The Wallonian Region has not yet announced a date and is expected to follow the European dates because the geographic difficulties to cover the whole region. In Wallonia, there is already an 80 percent DTT coverage.
Canada: The main FTA broadcasters (CBC, CTV, and Global) have launched HD streams of their programming in limited markets such as Toronto and Vancouver. Originally, unlike in other countries, Canada was allowing the market to determine when the analog switch-off begins. As a result, currently, analog and digital broadcasts co-exist, with virtually the only way to receive Canadian digital TV in most areas being via cable or satellite TV. In Toronto it is possible to pick up DTV over the air; in Montréal, Ottawa, and Quebec City a partial set of channels (most often CBC only) are offered – primarily as a vehicle for limited HDTV deployments. Much of Canada has some over-the-air access to US border stations, most of which offer ATSC DTV. Signal strength and quality vary widely. New TVs and DVD recorders often include ATSC tuners but basic converters for existing NTSC TVs typically are not readily available locally. As of May 2007, there are fewer than 20 digital television stations in Canada. On May 17, 2007, the Canadian Radio-television and Telecommunications Commission (CRTC, Canada’s broadcasting authority) ruled that television stations would be forced to switch to ATSC digital broadcasting by 31 August 2011, with minor exceptions in remote areas where analog transmissions will not cause interference.
China: The switch-off is scheduled to be in 2015.
Czech Republic started the switch-off in September 2007 and should finish by September 2010. A broadcast law amendment that would change this is awaiting approval.
Denmark began digital transmission in March 2006 and the analog network will be closed at the end of October 2009.
Estonia has a full digital signal by the 1st of August 2008, but analog broadcasting still continues for the first of two public TV channels (ETV) while the second is available digitally.
France will have completed the switch-off in 2011. 80% of the population will be able to see TNT in 2008.
Germany started the switch-off in the Berlin area, beginning on 1 November 2002 and completing it on 4 August 2003. It has also been completed in Bremen and Hamburg. “Simulcast” digital transmissions have started in other parts of the country, in an effort to prepare for a full switchover. The switch-off is planned to be completed by the end of 2008.
Greece: the switch-off will complete after the end of 2011.
Hong Kong’s analog broadcasting is planned to be switched off by 2012.
Hungary is scheduled to switch off analog broadcasting between 2010 and 2013.
Ireland‘s broadcaster RTE plans to make digital television available to most of the population by 2010, and the switch-off is planned to be complete by 2012.
Italy‘s government aims to complete the digital switchover by 2012.
Japan is also running an intense nationwide campaign announcing the planned switchover to digital on July 24, 2011. Many television stations around the country are already broadcasting simultaneously in digitally, or are planning to start digital broadcasts by 2007.
Kenya‘s Communications Commission of Kenya (CCK) announced that the country will start digital broadcasting in 2008 following preliminary work by the government. Kenya will be among the first countries in Africa to implement digital broadcasting.
Mexico has a 20-year plan to switch, with the target year of 2022 for the analog shut-off. Some digital signals are already on-air, the first being Tijuana’s XETV – an English-language affiliate of The CW serving primarily San Diego, California. Groups of cities that are required to simulcast digitally are added in descending order of size, with full coverage of the smallest centers required for 2021.
Malaysia: Information Ministry was planning to shut down the country’s analog television system in phases beginning in 2009 and set to convert to fully digital TV in 2015.
New Zealand: It was announced on 29 November 2007 that analog TV broadcasts will end within the next 6 to 10 years and expect a switch-off date to be announced by 2012. Digital broadcast via Freeview become available in late 2007.
Norway: The switch-off of the analog transmissions started in March 2008 and will progress region-by-region. The last analog transmitters are scheduled to close down by the end of 2009.
Portugal‘s government aims to complete the digital switchover by 2012; digital broadcasts will start in 2008.
Philippines: the National Telecommunications Commission will terminate all analog television transmission on December 31, 2015. ABS-CBN, the country’s largest TV network is planning to supply set-top boxes to areas in the Metro Manila market where the current signal of the network is weak and where it will give its stations in the digital platform.
Russia has announced that the switch-off is to be completed in 2015.
Slovakia: the government aims to complete the digital switchover by 2012.
Slovenia: the switch-off will be completed in 2010.
South Africa will start switch-off in November 2008 in preparation for the 2010 FIFA World Cup and should be completed by mid-2011.
South Korea’s analog transmissions will be terminated nationwide on December 31, 2012.
Spain: the switch-off will be completed on or before April 3, 2010.
Ukraine: analog transmissions will be terminated on 17 July 2015.
United Kingdom: The first switch off of analog television was on 30 March 2005, in the villages of Llansteffan and Ferryside in Wales. However, it was partially unsuccessful as residents insisted that BBC Two Wales be left broadcasting in analog as they felt that the digital replacement, BBC 2W, which opts out from BBC Two from 20:30 to 22:00 on weekdays, shows too much Welsh programming The switch-off of all analog terrestrial TV broadcasts resumed again on October 17, 2007, with Whitehaven in Cumbria and will now proceed region by region. The last regions will be switched off in 2012. In the UK, free-to-air digital broadcasts are branded as Freeview.
United States: By no later than February 17, 2009, all full-power U.S. power television will be digital, and analog transmissions terminated, according to legislation setting this deadline signed into law in early 2006.

Source: wikipedia.org