Difference between revisions of "Digital television"
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| Re position antenna, shift to different directions, use on screen signal meter, often located on TV menu or set top box, use better quality antenna, determine the location of power transformers, overhead lines, or electrical panels, avoid those locations. | | Re position antenna, shift to different directions, use on screen signal meter, often located on TV menu or set top box, use better quality antenna, determine the location of power transformers, overhead lines, or electrical panels, avoid those locations. | ||
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| − | In addition, being below average terrain, underground, or on the opposite side of a large bank of mountains and/or hills, such as areas | + | In addition, being below average terrain, underground, or on the opposite side of a large bank of mountains and/or hills, such as areas east of [[Los Angeles]] have been known to prevent the reliable reception of over the air DTV entirely without a more substantial and costly rooftop tower antenna setup. In lower signal strength areas, indoor antennas don't as often provide satisfactory results (more than three or so channels). Analog signals fade and degrade much more gradually than DTV. With DTV, you either get perfect reception, acceptably good reception, or none at all. |
==References and notes== | ==References and notes== | ||
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Revision as of 19:51, April 4, 2012
Digital television (DTV) is a new technology for transmitting and receiving broadcast television signals. The digital television format is also known as ATSC (which is actually the name of the agency responsible for developing digital television standards, the Advanced Television Systems Committee; the conventional North American analog TV format is NTSC, for National Television Systems Committee).
DTV provides clearer resolution and improved sound quality, albeit a somewhat shorter signal range. Older televisions which receive only NTSC (analog) signals will need a digital converter box to receive over the air digital television signals. These converter boxes will work with existing antennas.
Mandated switch to digital
In the United States, Congress has mandated a switch to digital television as of June 12, 2009. As of that date, traditional analog television broadcasting will cease, except for some low-powered stations and translators.[1]
Sub-channels
Digital television allows for sub-channels in addition to the main channel. For example, on the ION television network (formerly PAX television network), the digital signal from their broadcast stations includes the main channel, the Qubo cartoon channel, ION Life (a lifestyle, food, and exercise channel), and the Worship Channel. Thus, the digital broadcast signal from the local ION affiliate carries four channels instead of one. Other stations are doing likewise and carrying additional sub-channels, such as weather-only and movie-only programming, making the availability and quality of digital television programming available free over the air potentially comparable to that of cable television.
Effects of interference
A common belief used to promote this previously unheard of and unproven technology is the idea that DTV is somehow magically immune to the notorious effects of electromagnetic interference, such as ghosting (duplicate images and outlines of objects appearing on the screen), static, audio noise, and loss of color. In reality, DTV, both satellite, digital cable, and digital terrestrial television face equally serious problems of their own.
Effects of Inteference on digital terrestrial television
| Effect | Cause | Solution |
|---|---|---|
| Complete loss of signal | Improper antenna position, loose connection, TV transmitter located too far away | Re position antenna, shift to different directions, use on screen signal meter, often located on TV menu or set top box, use better quality antenna |
| Picture freezes, audio cuts out or stutters | Improper antenna position, loose connection, TV transmitter located too far away, presence of atmospheric interference, lightning, or improperly shielded electrical equipment | Re position antenna, shift to different directions, use on screen signal meter, often located on TV menu or set top box, use better quality antenna, determine the location of power transformers, overhead lines, or electrical panels, avoid those locations. |
In addition, being below average terrain, underground, or on the opposite side of a large bank of mountains and/or hills, such as areas east of Los Angeles have been known to prevent the reliable reception of over the air DTV entirely without a more substantial and costly rooftop tower antenna setup. In lower signal strength areas, indoor antennas don't as often provide satisfactory results (more than three or so channels). Analog signals fade and degrade much more gradually than DTV. With DTV, you either get perfect reception, acceptably good reception, or none at all.