Today many people around the world still watch the TV signal their parents or grandparents first saw in the 1940s -- a picture made up of 525 thin horizontal lines transmitted by an analogue system that works like AM/FM radio. And - by the way - itīs proven to work.
So, what makes digital television so special and why should one change ? In fact, there are several good reasons why mostly all countries are choosing to switch from analogue to Digital TV, as you can see in the following.
a) Multi-Casting
By using of sophisticated compression technology you can stuff a lot more information into a digital signal (4+ programmes / channel) than an analogue signal (1 programme / channel) for the same amount of bandwidth. This allows to send out different types of programmes (e.g. Sport, Home-shopping, Children TV, Regional Programmes etc.) for the whole family in just 1 channel.
b) Stable Picture Quality
Remember the days before digital television when someone in the family would assume the job of an antenna contortionist ? A digital signal doesn't produce the same problems with the picture we see on a distant analogue television. As long as the TV receives a signal, the picture quality is, due to sophisticated error correction mechanisms, perfect
c) Higher Resolution
Some NTSC (PAL) television sets can display a picture 720 (768) pixels wide by 486 (568) pixels high. That's a total of 349,920 (442,368) pixels. It sounds like a lot, but it's pretty low resolution compared to High Definition TV. HDTV can have a resolution of up to 1920 x 1080. That's 2,073,600 pixels, or six (five) times more pixels than the older resolution. So, when you look at comparable sizes of HDTV and NTSC/PAL sets, the HDTV set will have smaller, square pixels, and more of them. Images will be crisper and cleaner, with more detail in every close-up and every panorama. For details see table below
Standards Comparison Table
d) Enhanced TV
Television in the digital age won't be limited to video and audio; our televisions will become truly interactive by including data transmission stored on the set-top box and some day - hopefully - back-channels.
e) Digital Surround Sound
Digital TV will broadcast sound using the Dolby Digital/AC-3 audio encoding system. It's the same digital sound used in most movie theaters, DVDs, and many home theater systems since the early 1990's. It can include up to 5.1 channels of sound: three in front (left, center, and right), two in back (left and right), and a subwoofer bass for a sound you can feel (that's the .1 channel). Sound on digital TV will be "CD quality" with a range of frequencies lower and higher than most of us can even hear.
In addition - rare "on air" transmission frequencies
Beside the above mentioned technical issues there is also a serious commercial aspect behind changing to digital TV. Traditionally in every country around the world frequencies for "on air" transmissions are rare. Used by radio, television, police radio, airplanes, GSM etc. it is always in demand and therefore expensive.
So the perhaps most important reason for switching mostly all different countries around the world to digital television is, that it frees up frequencies by two different ways:
a. using sophisticated digital compression technology which allows to stuff ~400% more information into a digital signal than an analogue signal and therefore reducing the need of "on air" frequencies by a factor of at least 4, or
b. by using different transmission platforms than the traditional "on air" transmission. Those new transmission platforms, now as we talk about digital signals, could be the worldwide exploited high speed broadband networks and data highways, reducing the need of "on air" frequencies to Zero.
Those now freed frequencies then could be auctioned for new services like GSM, UMTS (3G), etc. That's essential to balancing the governmental budgets, because the auctions of those frequencies are bringing in billions of EUR, as seen already in several countries -- and an estimate of that money is already included in governmental long-term fiscal plans.
How do atecom products fit into this scenario ?
To clearly understand this, we have to have a look at the 3 different transmission phases of Digital TV.
As the compressed Digital TV signal itself is a recording standard, one had to think about adapting the digital TV signals into an appropriate transmission protocol, which guarantees the loss-free real-time transmission of the digital signal to customers TV set. For the first two phases of the transmission, the relevant international standardization bodies, known as Digital Video Broadcasting (DVB) group, decided to use the so called Asynchronous Transfer Mode (ATM) as recommended transmission protocol.
atecom - as ATM expert - is involved in the professional part of the transmission, as described as phase 1 and 2 below. Our different product lines are covering the adaptation of digital video signals into ATM cells and the loss-free transmission over Wide-Area-Networks and vice-versa at the receiving end.
1. Phase: Contribution
This describes the transfer of Digital TV between broadcast studios (regional to main studio and vice-versa) and between so called event locations (e.g. football stadiums, concert halls, formula 1 race tracks, horse race tracks etc.) and the broadcast studios
2. Phase: Primary distribution
Describes the transmission between broadcast studios and the last "professional" transmission point
3. Phase: Secondary distribution
Describes the "last mile transmission" from the last "professional" transmission point to customers set-top box at home, also known as DTH (Digital to Home)
