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 History of Scented Candles

Not many people seem to know this… By the end of 2012 the UK will have been the only country in the world to have totally made the switchover to all digital television. The digital switchover starts in 2008 – less than 2 short years away.

A recent Which Report (Which is the major consumer champion in the UK) shows that in many areas the awareness of the digital switchover is less than 2 %. Even in the Borders Television region – the first to make the change – only about a third of the people surveyed knew what was going to happen.

It really does seem that the UK is sleepwalking in to the Digital Switchover.

Not surprisingly, the whole switchover programme is being watched with keen interest by other nations around the World. The benefits of digital television for broadcasters, manufacturers and programme makers are pretty clear. The new media is already changing programme making – Planet Earth, currently showing on the BBC – is a prime example of what can be achieved. And of course the manufacturers are positively drooling at the thought of all the new televisions, video recorders and set-top boxes they expect to sell.

Consumers are set to benefit too – better pictures and sound, high definition television, interactivity, movies on demand… The list goes on.
Governments have a keen commercial interest too. They own the air waves. And digital television takes up much less band width than conventional analogue signals. So the move to digital frees up precious broadcasting capacity that Governments are keen to sell to the highest bidders. The sale of the mobile telephone spectrum for 3G providers raised over £20 billion. Who would bet that the sale of the television spectrum won’t raise significantly more?

The move to digital television benefits us all. So why do so few people know what is happening?

Simply being able to receive digital television is only part of the issue. Just about every television bought more than 12 months ago, and a good percentage of those being sold now, are effectively obsolete. All of them will need a separate satellite receiver or set top decoder box to receive digital signals. Every video recorder will also need an additional decoder.

The UK Government puts the average cost per household to upgrade to digital television at £132 ($210). I feel the real figure is likely to be 4 or times this level. Most homes in the UK have upwards of 4 televisions – each and every one will need significant investment to receive digital television signals.

In the UK 68% of homes already receive digital television in some form- satellite (which means BSkyB – the only UK satellite television provider), cable or terrestrial freeview. In almost all cases digital television is only watched on the main television in the house. The other sets are still restricted to the main analogue, terrestrial stations. From 2008 this has all got to change.

It’s time to wake up. We are at the threshold of the biggest change in the television experience since it was first invented.

Start planning your own digital switchover now.

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.