Digital TV Sets - Important Facts To Know When Buying A Digital Television
Cut through the confusion when buying a new TV set to watch digital TV. Learn a few facts about digital televisions and digital TV broadcast services before going shopping so that you can buy with confidence.What is a digital TV anyway?
Most people including TV salespeople seem to think that a digital TV set is a box that you watch terrestrial digital satellite TV broadcasts on. This makes no sense at all to me because all my TV sets are analogue and I manage to watch digital television on them with no problem at all.
Now giving something a name that isn't quite right is ok until the name that you give it suggests that the item is actually something quite different to what it really is. When I think about digital TV receivers I have a mental picture of what it is. I'm sure that a lot of people have ideas and mental pictures of digital TV sets that don't match with the one I have so I'm going to try and give you a few facts to help to clear up the confusion.
Sattelite Television
Satellite TV is a system where transmitters on the ground send TV signals to an orbiting satellite receiver. Satellite TV is then relayed from the orbiting satellite to a dish on your property. These signals are then processed before they are displayed on your TV set. Sattelite TV signals can be analogue or digital.
Digital Satellite Television
This is a system the same as the generic satellite TV system above but now we are talking only about transmission and reception of digital TV signals. When your dish receives these signals they must be processed and decoded before being displayed on your Television set.
Terrestrial and Cable Television Systems
There is the same analogue/digital distinction when you consider terrestrial or cable TV services. Both are capable of delivering either analogue or digital television or even both in some cases.
Analogue Television Set
All but the latest TV sets must convert any signal it receives to analogue in order to display it on a conventional Cathode Ray Tube or CRT. As far as I'm concerned any television set that does not have a digital display like a liquid Crystal or LCD must be called analogue.
Digital Television Set
This is where the edges of the definition start to get a little blurry. To be a true digital TV set there must be no analogue signals within the apparatus at all. Some of the newer LCD televisions would fall into this category, as might your PC if you use it to watch digital TV for pc using a digital tuner as well as a digital LCD screen rather than a CRT.
So we now know what a true digital TV set is but this isn't the whole story. There are several in between cases where TV's seem to get called 'digital' even though they are in fact analogue sets.
100Hz or 120Hz Scan Rate TV Sets
Traditionally 60 or 50 still pictures every second have created your TV picture. The actual number of stills or frames per second is dependant on where you live. Each still picture is shown one after the other to give the illusion of motion.
Now 50 or 60 pictures a second is ok to watch but it does tend to produce a slight visible flicker. You can best see this if you look at the screen out of the corner of your eye where it is more sensitive to the flicker. Doubling the scan rate by showing 100 or 120 pictures per second reduces this flicker to the point where most people would not be able to see it at all. Television Sets using this technique can display a very nice picture indeed.
Why am I talking about double scan rate TV's?
Well the only practical way to double the scan rate of your TV display is by using digital techniques and this fact might excuse you from calling the set a digital TV because the digital circuitry to do this is complex relative to the analogue portion of the set. TV Sets With a Digital Tuner Some manufacturers are now supplying TV sets with a built in digital tuner. Instead of using an analog converter digital TV set-top box to convert the digital signal from your dish, antenna or cable into an analogue signal that is fed to your TV. The incoming digital signal can be plugged straight into your TV set. The set-top box is now inside your TV. This is the type of TV, which I think most people are referring to when they talk about a digital TV.
I don't like the integrated digital tuner approach because typically they only allow you to receive "off-air" terrestrial digital broadcasts. If you decide to use digital satellite or cable then you will need to purchase a set top box and the extra cost for the integrated digital TV is wasted. I'm sure that sooner or later TV's will include apparatus to allow for digital sattelite and cable as well as digital terrestrial. Eventually they will even be able to cope with the different encryption and pay-for-view schemes. Until that happens I shall be sticking with a set top box to decode my digital TV.
Digital TV For PC
You may not have considered this but why not watch digital TV on your PC? It's now very easy to do this by buying one of the many available DVB Digital Video Broadcasting) USB adapters. You simply install some software and plug the digital TV adapter into a spare USB socket on your PC.
A notebook PC makes an excellent compact TV set when used with a DVB USB adapter. These devices are predominantly available for digital terrestrial TV but a few claim to work with digital satellite TV and even cable. However, as far as I can see they are only suitable for watching free-to-air services. If you want to subscribe to encrypted pay-to-view services then you will need a set top box capable of receiving and decrypting those services.
So you see, a "Digital TV Set" might not be what you think it is and it may not be as desirable as the salesperson would have you believe it is. It certainly isn't your only option so make sure that you've done your homework before you go shopping.
Written by: Steve Gee