What’s This Digital Television Thing All About?

What is DTV?

Digital television is the next generation of video broadcast technology. The old system, called analog television, was created in the 1950s. DTV was created for the 21st Century by a working group of programmers, broadcasters and engineers, so that consumers will get the best product. The same way computers scan photos into data files (literally turning your vacation pictures into a series of 1s and 0s); DTV changes the film and video into digital images (those same 1s and 0s) and transmits them.

Analog still works, so why switch?

They used to say, “If it ain’t broke, don’t fix it,” but 8-track tapes were replaced by cassette tapes, which were replaced by CDs and so on. New technology does the same thing, but does it better. By changing the way TV signals are broadcast, the signals use less bandwidth, meaning more programming can be sent out over the airwaves. According to the FCC website, “That means better quality, more choices, and more control over your television.”

Using less bandwidth also means parts of the broadcast spectrum will no longer be needed by the TV industry. This spectrum is limited, like a series of pipes; there are many, but only so many. DTV means television needs fewer pipes. The others can be reassigned to public safety–police, fire and paramedic services–or wireless phone service providers or other uses.

When and how did the switch happen?

The Federal Communications Commission (FCC) started setting up the switch-over in 1996. Starting March 1, 2007, all televisions built in or imported to the US must have a digital tuner as well as an analog tuner. Many stations launched digital broadcasting in addition to analog broadcasts in late 2008 or ’09. On June 12, 2009, all major TV stations ceased sending out analog signals. A few small, local TV stations will continue using analog.

Consumers who purchased TVs built March 2007 or after didn’t need to do anything; they were built switchover-ready. In fact, the switchover went smoothly, most people probably didn’t even notice it was happening. Those with older sets can buy a new TV or a converter than translates digital back to analog signals.

Analog-only TV sets built before March 2007 may still be available for sale; if so, retailers must to post a notice clearly stating which sets are analog-only.

Will consumers need a special antenna to get digital television programs?

Consumers who currently use an antenna, either on-the-set ‘rabbit ears’ or a roof-mounted antenna, should receive digital signals as well as they received analog signals.

Is this related to high-definition television?

No, HDTV is a separate issue. HDTV audio and video signals were always digital, this action means that regular TV (sometimes called ‘enhanced’ television or ETV) are is also now digital. Consumers do not have to buy an HDTV to see digital-TV programming. Broadcasting programs in enhanced and high-def formats is called ‘multi-casting,’ which will be one of the big advantages of the digital switch.

Other useful facts:

Consumers who decide to buy a new television don’t have to send their old set to a landfill; many communities have recycling programs.

Cable systems are not required to switch to digital; many cable companies offer digital and high-definition program packages as well as analog. Some may eventually choose to switch to all-digital programming. The FCC’s DTV rules apply only to broadcasters–those who use the public airwaves to deliver programming to consumers.

Parental controls (like the V-chip) will work as well with digital signals as they have worked with analog.

Like all consumer electronics, televisions have changed a lot over the past fifty years. With few exceptions, these have been changes for the better. Digital television is simply the newest member of that list.

The Digital Television Revolution

The 2012 London Olympics really brought home to me just what a massive technological jump in digital media has occurred during the last few years. There has been significant advances in digital compression and transmission.

This year, in addition to high definition broadcast, which made its appearance in the 2008 Beijing games, 3D television was also added to the line up, offering more channels and choices. With analogue television broadcast almost becoming extinct, digital televisions promise of delivering more for less has become a reality. Now, how did we arrive at this point and what does the future hold for digital multimedia?

Prior to the digital switchover, analogue television was resource hungry in terms of the amount of bandwidth required to carry a single channel. This is typically between 6 – 8 MHz depending on the type of video standard being used. This limited the number of channels which could be transmitted, since there is a finite amount of spectrum that must be shared with other services such as mobile, radio and two way communications.

What the digital standards of ATSC (North America) and DVB (Rest of the World) provided was the ability to reuse the existing analogue spectrum more efficiently. This meant a typical 8 MHz carrier used for analogue broadcast could be converted to DVB-T (Digital Video – Terrestrial) making it possible to carry 9 standard definition channels or 3 HD channels plus one SD channel for the same amount of bandwidth.

It would have required in excess of 70 MHz of frequency spectrum to achieve this with the old analogue standard. In addition to squeezing more channels into less space, digital television is much clearer and doesn’t suffer from ghosting or other artifacts which troubled analogue systems. Being digital also allows other features like improved digital sound, electronic program guide and subtitle support to be included.

Televisions are sold with the digital decoder integrated and older televisions can use a separate set top box. As technology advances, we will also see improvements in the compression techniques used, which means even more content for digital media, already this has enabled 3D broadcasts for some events such as the Olympics.

The Future

Eventually as fibre to the home is deployed worldwide, the all IP enabled set top box will replace the DVB standard, since the IP set top box has a distinct advantage over digital broadcast technologies, specifically multicast join requests. Unlike DVB-T or DVB-S, IP multicast allows the receiver to send a join message to the network for the desired channel then if the request is successful the broadcast is routed to the receiver, only the bandwidth for the requested channel is used. With the DVB standard, all available channels are being broadcast simultaneously, and the channel count is limited by the finite amount of channel bandwidth regardless of the compression techniques being used.

The IP set top box can support both selective multicast (one to many) and on demand unicast (one to one) broadcast, this allows for virtually unlimited amount of content. However, unlike DVB, IP set top boxes have to worry about latency and QOS, since there is traffic contention with both residential broadband and IP Telephony. A poorly implemented IPTV deployment can behave like analogue television in an over subscribed service provider network, unless the correct traffic management is in place.

High Definition

Today HD is regarded as premium content by most operators and is charged at a higher rate than SD (Standard Definition). However, over time this will change as people upgrade their televisions to HD models. Today there are two standards for digital HD broadcast, 720p and 1080i. The ‘p’ means progressive and the ‘i’ means interlaced. In 720p broadcast, the picture is made of 720 horizontal scan lines and a vertical resolution of 1280 pixels, which has the advantage that one frame represents a complete image.

In 1080i broadcast, the picture is made from two 540 horizontal scan images which when combined make 1080 lines. The vertical resolution becomes 1920 pixels. Most modern televisions support playback of 1080p, which is definitely more desirable than 1080i especially in fast moving sequences where motion blur can be experienced. However, on modern televisions the difference is barely discernible.

Initially the public uptake of HD was slow, the receivers were expensive and the available content was limited. HD television has really been an evolution rather than a revolutionary change for most of us and this is also true of digital television in general. As digital switchover continues worldwide and consumers replace their televisions, digital will become the new standard. However, it is unfortunate that technology won’t help to improve the content.

Which Kind of Television Is Best for Your Home Theater?

Much debate has been made in the name of which television offers the best user experience. When you sit down in front of the big game, which television format is going to give you the best picture, the best price, and the best overall experience? While it may not be possible to say whether LCD, Plasma, or LCD is going to be the best choice for you, it is possible to put together a list of some of the pros and cons of each format to help you make a decision as to which format will offer you the most of what you want with the least of what you don’t want.

LCD
LCD televisions have been quite popular for some time now and have become something of an “industry standard” if there is such a thing for the television market at this point in time. The fact of the matter is that when you go to your local “big box” store and walk into the electronics section, most of what you see in front of you are LCD televisions. So why are LCDs so popular? One great advantage of LCD televisions is the fact that they offer very low glare and can be watched in a higher light environment than a plasma television. Another advantage of LCD will come at the end of the month in the form of a lower energy bill. LCD televisions as a rule tend to use less energy than some of the alternative televisions. While LCD televisions have a lot to offer, many people feel that plasma televisions offer a better picture at a lower cost.

Plasma
Plasma televisions were more popular several years ago than they are now but many people swear by them, and for good reason. Plasma televisions cannot be viewed as easily in high light situations as LCD televisions due to glare, but plasma screens are known to offer what many people consider to be a more vivid picture and deeper colors, especially blacks, than some of the alternative options. Another great feature of plasma televisions is their price. As LCDs and LEDs are gaining market share it is becoming possible to find some really great deals on plasma televisions. If you are planning on having a television for primarily home theater, lower light situations, then a plasma television may be exactly what you are looking for.

LED
LED televisions are essentially the next generation of LCD televisions, this is because the LED moniker refers to how new LCD televisions are backlit rather than an entirely new system onto itself. So when thinking of an LED television you can expect some of the same benefits as with an LCD like low power consumption, a thin physical build, and a great low light viewing experience with the added benefit of improved color saturation.

Whatever television you decide is the right choice for you, I’m sure you will be amazed with the high quality that many companies are offering across the spectrum of television formats these days. Basically, it’s hard to go wrong with a great new television!