The digital switch-over is going on over here at the moment (in the UK). The government says that the analog signals will be switched off in the UK in 2012. Although some areas, such as the Scottish Borders, have already been switched off.
I have to say I'm not a fan of them switching off the analog signal even though I already have digital TV. If you do have normal digital tv and not the new fangled V+ or Sky+ boxes, you can't tape a channel and watch a different one. So once they switch off analog, this will cause me problems.
If I understand correctly,all the US TV stations have been transmitting digital for some months (or maybe even a year or two). The "changeover" is when they turn off analog. Turning off analog has already been tested in one city in the US, with "mostly-good" results.
http://www.google.com/search?q=wilmington+dtv
I don't have any idea why they need to switch it off, can't they just keep it on? What harm will it do? Is it just so they can flog the frequencies the analog currently uses and make some money out of it?
Well, a TV transmitter uses a substantial amount of electrical power (around a megawatt, the equivalent use of hundreds of houses), and transmitting both analog and digital requires separate transmitters and is a duplication of services. If it were left to the stations, they would probably continue to transmit analog for a few more months or years (at least in the US where TV is advertiser-supported), while encouraging remaining analog viewers to 'upgrade' to digital so the station could finally shut down the analog transmitter without losing too many viewers.
But yeah, the selling of the analog bandwidth is basically it. Not sure about other countries (though I do know there's a lot of international cooperation on what services use what frequency bands), but in the US the FCC auctioned off the analog TV bands YEARS ago. I recall it went to future cellphone and similar (WiFi and WiMAX) uses that expect a lot of growth, so it's not going to go to waste (though no doubt tons of analog TV's are going straight into landfills).
