Digital TV service is the provision of television via digital signals rather than the traditionally used analog signals. Several countries worldwide have switched to, or are in the process of switching to digital TV service, and ceasing analog broadcasting altogether. In June 2009, the United States Federal Communications Commission (FCC) switched all high-power over-the-air TV broadcasts to digital TV service, per the Advanced Television Systems Committee (ATSC). The switch over affected nearly two million households across the country that still relied on analog transmission as of 2009. Canada and Japan are slated to switch to digital TV service in 2011, while China is expected to switch over in 2015.
In the US, digital TV service supports both Standard Definition TV (SDTV) and High-Definition Television (HDTV), which cannot be transmitted via analog signals. Digital cable and digital satellite are perhaps the best known modes of digital TV reception, along with picking up signals via the Internet. Digital TV can also be transmitted via Digital Terrestrial Television (DTT), whereby the signal is received by antennae and is limited to whichever stations the antenna picks up.
Digital TV channels take up less bandwidth than analog, and can also feature more than one program on the same channel using a feature known as multiplexing. However, digital TV also takes longer to change channels, and significantly slows down channel surfing. In order for non-digital televisions to accommodate the switch over from analog to digital, they require a connection to a satellite system or an off-air external tuner. However, digital TV boxes may cause certain analog televisions to lose some of their functions, such as the ability to change the channel using a remote control and the ability to record programs using a DVR.
The switch over to digital TV service has created environmental issues when it comes to disposing of obsolete analog receivers. In the US alone, nearly 100 million analog receivers are presently in storage. Some of those which are salvageable are then fitted with digital converters; however, many are discarded into landfills, where their toxic metal material poses an environmental hazard. Because of these complications, some pawn shops have stopped accepting analog televisions.