TVEffects
 
  Digital Television(updated from an article written in 2002)

The current analog television standard in use in the US (NTSC) has been in place for over 50 years and is currently in transition to a new digital standard. This section explains the basics regarding digital television, its impact on the consumer and its impact on those involved in producing television content. Canada adopted their digital standard in 1997.

What is Digital Television?
Digital television is the digital broadcast standard mandated by the FCC to replace the antiquated NTSC broadcast standard in the US. While many countries also have similar initiatives underway, the FCC only has jurisdiction in the US, therefore other countries are likely to adopt other standards. The Digital TV (DTV) standard is likely to produce a lot of initial confusion, because it actually consists of different implementations, depending upon which "flavor" of digital that the broadcaster decides to implement. The basic choices available to them are: High Definition Television (HDTV), Standard Definition Television (SDTV) or a combination of the two. (Some are electing to do both depending upon the time of day, for example, broadcasting SDTV during the day and HDTV during evening primetime.)

High Definition Television (HDTV)
HDTV provides for the following enhancements over analog television:

  • The HDTV standard calls for 1125 horizontal lines of which 1080 are active. The remaining lines are used by the VBI and data.

  • Offers 5.1 Channels of Dolby Digital surround sound. Three channels are in front, two in back with a subwoofer bass. (The subwoofer represents the ".1".)

  • Supports a maximum resolution of 1920 x 1080 pixels. (Compared to 720 x 486 under the NTSC standard)

  • 16:9 Aspect Ratio translates into a wider screen that equals the aspect ratio of most theaters. (The NTSC aspect ratio is 4:3)

Standard Definition Television (SDTV)
SDTV allows broadcasters to multicast four or five standard feeds instead of one HDTV signal. The resolution and sound quality exceeds NTSC standards, but are not as high as HDTV. (For example, HBO1, HBO2, HBO3, etc. are examples of the expanded programming that becomes available to broadcasters that elect the SDTV option.)

Why the Switch to Digital Television?
The switch to DTV has many reasons behind. The reasons stem from quality to practical reasons such as not enough available frequencies to allow for continued growth and expansion. From a quality perspective, DTV signals eliminate many of the transmission problems inherent in analog signals such as snow, ghosts, screen flicker, etc.

Why Digital Television?
From a quality perspective, DTV signals eliminate many of the transmission problems inherent in analog signals such as snow, ghosts, screen flicker, etc. In addition to the enhanced sound and picture offered by DTV, there are at least four additional substantial benefits.

1) DTV enables more programming to be offered using the same bandwidth of analog broadcasts.


 

2) DTV enables new services to be offered through additional data that is transmitted along with the sound and picture information. This allows broadcasters to offer services such as interactive TV, web pages, multiple language captions, news, weather, sports, etc. Additional abilities that can be offered include allowing the user to interactively bring up additional information on a product that is advertised or allow them to select which camera feed they wish to watch during a live broadcast such as the Superbowl or Academy Awards.

3) Enables error correction to be applied to the broadcast signal in a manner that cannot easily occur with analog signals.

4) Allows the FCC to free up a substantial block of frequencies to be re-purposed for other areas such as public safety.

Both HDTV and SDTV allow broadcasters to deliver additional data along with the broadcast signal to allow for new services such as interactive TV, web pages, multiple language captions, news, weather, sports, etc. Additional abilities that can be offered include allowing the user to interactively bring up additional information on a product that is advertised or allow them to select which camera feed they wish to watch during a live broadcast such as the Superbowl or Academy Awards.

Another less obvious benefit of digital broadcasts is that it frees up a large portion of the broadcast spectrum which allows the FCC to repurpose the signals for other uses such as local public safety.

What is the Timeframe for Digital Broadcasts?
The transition to digital is already underway. According to the FCC's accelerated schedule, everyone in the country is scheduled to have at least some access to DTV broadcasts in 2002.

The first stations began to broadcast in digital in 1998 and the transition for all stations to broadcast in digital was scheduled to be complete in 2006. The date was modified to February 2009.

Will You have a Choice Between Analog and Digital TV?
In the near future, there really will not be a choice. As of the current FCC schedule, if you want to watch television in 2009, you will either have to have a digital TV or digital converter (this includes most cable boxes). Prior to 2009, broadcasters are required to simulcast signals in analog and digital so there is a choice until then.

What Happens to Analog TV?

In time, analog sets will join the ranks of vinyl album record players. They will stop being manufactured and will no longer be commonly found in households.