What to Do About Digital - 5 : Buying a New Television Set, Part 3 (LED or Not LED?)

An alternative sub-title for this article could be: "When is an LED tv actually an LCD tv?". The answer would be "always".

"LCD" stands for Liquid Crystal Display. "LED" stands for Light Emitting Diode, as used to show your tv is in standby or in house/garden lights, for example. There is much misunderstanding about these two terms when used to describe televisions, much of it down to the industry itself not making things clear. The real danger is you may not think you are confused about it (see the final paragraph). Here's an explanation.

All current flat-screen televisions are of two types: plasma or LCD. Notice the absence of the term "LED". The description "plasma" or "LCD" refers to the panel which provides the pictures you watch. Each panel is made up of individual picture elements called pixels. A standard definition tv panel contains around half a million pixels, an "HD-Ready" tv panel has around one million pixels while a "Full-HD" panel has around two million pixels.

The pixels in a plasma panel emit light themselves, much like the old CRT (cathode ray tube) televisions produced light from the end of the CRT which provided the screen. However, the pixels in an LCD panel do not produce any light themselves. They need to have light shone through them otherwise they cannot be seen.

This is where the LED part comes in. LEDs can be used to provide that light source behind the LCD panel. Such tvs are simply called "LED-tvs". Previously, the light source for LCD tvs was a panel made up of one or more CCFLs (cold cathode fluorescent lamps: using technology like household low-energy lamps) or an electroluminescent panel (as used in large advertising signs) which was placed behind the LCD panel and made to glow all over with an equal brightness by using a diffuser. You can still buy tvs like that: they're just not called "LED-tvs".

As technology has progressed, a panel of LEDs behind the LCD panel was found to offer an advantage over the CCFL or electroluminescent panel. LEDs could be grouped and the brightness of each group adjusted according to what the LCD panel was showing. Bright areas of the image caused the LEDs in that region to shine brightly, while dark areas of the image would cause the LEDs behind them to dim down. This improved the response of LCD screens to black, previously one of their downfalls.

Later it was discovered that a clever arrangement of LEDs just behind one or more edges of the LCD panel could achieve a similar result, using some sort of mirror arrangement. This resulted in the ability to produce extremely thin LCD tvs, especially desirable for wall-hanging.

Thus LED-tvs are of two types: back-lit and edge-lit. You'll see one of these descriptions in each tv's specifications, though the differences are becoming blurred as the technology advances.

There can be problems with all these technologies. The back-lit CCFL or electroluminescent panel can suffer uneven illumination, especially with larger screens when more than one CCFL is needed - quite a disaster for the resulting picture: always check such a set for that problem. Back-lit LED-tvs can suffer a bloom around dark areas. The LEDs behind the LCD panel are not as numerous as the number of pixels in that LCD panel, so dark and light areas will not match up with the groups of LEDs exactly. Side-lit LEDs can show a glow in the corners of the screen, especially when viewing from a wide angle. All these points are things to watch out for when selecting a new tv.

So you can see that, if we're to describe televisions according to the type of panel used for displaying the image, LCD is the acronym to use. LED is just a description of how the essential light source is provided.

Evidently it's perfectly possible for members of the public not to know they are confused by this. I was once told by a very knowledgeable and experienced sales assistant in a notable tv shop about a lady who asked to see some LED televisions. When he told the lady that all such televisions were actually LCD tvs, she would have none of it. She told the assistant he didn't know what he was talking about and promptly exited the shop!

What to Do About Digital - 4 : Buying a New tv Set, Part 2 (3D or not 3D?)

You cannot fail to have noticed the way 3D viewing has become all the rage these days, both in the cinema (where it started) and in the home with 3D televisions. Without going into the long history of 3D development which has brought it to its current state, there are a few points which are worth making.

There are two kinds of 3D video technology which can be summarised as "passive" and "active". In the cinema it is the passive form. This means the inevitable spectacles are simple pieces of polaroid material, quite cheap, and the digital projection is of two images which are filtered by the glasses so one image is seen by the left eye and the other by the right eye: much better than the fifties 3D versions (remember Vincent Price in "The House of Wax"?) where the glasses contained acetate film of two different colours which interfered with the colour rendition of the image and which gave different light intensities to each eye.

3D television uses the active form, except for the LG company which is championing the passive form. Active 3D imaging uses expensive spectacles which have electronics built into them and which are synchronised with the image on the screen. It's called "active shutter technology". The image on the tv screen very quickly alternates between two versions, one for the left eye and one for the right eye. When it's displaying the image for the right eye, the left glass of the spectacles goes dark and prevents light reaching the left eye: vice versa with the following image, and so on.

Now this rapid switching of light to each eye is not everyone's cup of tea. Indeed, there have been reports of induced nausea and headaches by viewers. If you decide to embrace 3D technology, do test yourself in the shop before you buy to see if you react in that way. Give yourself plenty of time to watch the demonstration screen. It's clearly a personal response: some people will be affected and others not.

There are also technical problems associated with this rapid switching on the screen. All LCD tvs have a response time, which has been reducing as the technology advances. This is the time it takes for the tv screen to "lose" one frame while generating the next frame, essentially. The longer the response time of the screen, the slower will the screen be to change frames, resulting in some very peculiar artefacts on the screen. Bearing in mind that, in general, you're watching twenty-five frames each second (there are variations on this, depending upon the tv set and what you're watching), so we're talking about very small intervals of time. Nevertheless, LCD screens tend to have a slower response time than plasma screens, all other things being equal.

To display active 3D images, the switching involved should not leave any traces of a preceding frame, otherwise the integrity of the 3D image can be compromised. If you decide to go for 3D, do compare a plasma tv set with an LCD tv set, side by side (though you'll have to switch spectacles between looking at each one).

Regular 3D tv broadcasting is some way off yet. The major current source of 3D material is from the high-definition Bluray discs, where they contain a 3D version of the film. You would need a 3D-enabled Bluray player and a 3D-enabled television or projector to watch such discs. Most manufacturers currently include a few 2D-only sets in their catalogue, though they will be at the cheaper end of the range. Most R&D is going into 3D sets so they will have the latest technology even for producing a good 2D picture. It may be, therefore, that you would end up buying a 3D set but use it only to view 2D pictures. You can't help feeling you would be paying for something you're not going to use, but there's little alternative. It's like the gentleman who, visiting a tailors, finds just the suit for him but it's a three-piece and he doesn't want the waistcoat. Upon being asked about that, the salesman replies that the waistcoat is optional; it doesn't have to be worn!

Next time we'll be looking at the question: when is an LED tv actually an LCD tv?

What to Do About Digital - 3 : Buying a New Television Set, Part 1 (Hi-Def or Not Hi-Def)

Maybe, after reading the second article in this series, you decided it was time to replace your ageing television set rather than add a Freeview Set-Top Box to it. This article is for you, then. What do you need to think about and what decisions do you need to arrive at, even before you've set foot in a television shop or investigated on-line shopping?

There are many such matters to ponder: High Definition or not is possibly the first one. All current televisions of any note are flat-screen and come with a built-in digital (Freeview) tuner. In some of them that tuner will also receive the new High Definition transmissions starting at the Digital Switchover next March. Do remember that the average life-expectancy of a tv set is ten years and that many will go well beyond that. A decision now has to last, then. I would advise going for a tv with a High Definition tuner, but they are slightly more expensive than those with just a Standard Definition tuner. In the near future you probably won't have that choice - they'll all have the High-Def tuner as standard.

Why am I recommending this pathway? The likelihood is that your new tv will have a larger screen than your current tv. High Definition allows you to:
a) view a smaller screen from a nearer position;
b) view a larger screen from your current position;
while giving you a very clear, high resolution picture, showing much more detail than is provided by Standard Definition.

Of course, many tv stations are only Standard Definition and if you get too close to the screen or have a very large screen that picture is not particularly good. Need to have movable chairs, therefore, and the space in which to move them. Many years ago there were recommendations about screen size and viewing distance. These have changed since the advent of High Definition and the current Hi-Def recommendations are:

32" to 37" screen : 1.3 metres (just over 4 feet) viewing distance.
40" to 42" screen : 1.6 metres (just over 5 feet) viewing distance.
46" screen : 1.8 metres (just under 6 feet) viewing distance.

These are minimum recommended distances. The maximum distance is around double that distance. How can there be a maximum distance? It's the distance beyond which you won't really be able to notice that a Hi-Def picture looks better than a Standard-Def one. So the size of screen to go for is intimately tied up with the Hi-Def or not decision. The larger the screen, the more expensive the tv set; all other things being equal.

While you deliberate on all that, do have a look at a friend's or relative's tv if they have Hi-Def (Sky or Freesat) and carry out some experiments walking towards and away from (backwards!) the tv on both Hi-Def and Standard-Def tv stations, and see what you can notice. While you're doing all that and coming to a decision, I'll prepare Part 2 of this article - "3D or 2D?" (though you may have already decided on that).

Just one final point about High-Def. On Freeview, as on Freesat, there are four Hi-Def tv stations:
BBC-1 HD
BBC-HD
ITV-1 HD
C4-HD

BBC-HD shows a variety of programming from all its other stations, including repeats of BBC-1 HD material. All its output is in Hi-Def.
Not all programmes shown by the other stations are made in Hi-Def. Those that are usually are indicated as such in listings magazines. If "HD" is not included in the listing information then the programme is Standard-Def. It is then what is called "upscaled" before transmission. Your tv would do that to the Standard-Def station's transmission anyway, so it's nothing special.

Sky transmits many more High-Def stations, but you have to pay a subscription and have a satellite dish installed. Blu-Ray discs (BDs) are the High-Def version of DVDs. They produce a better quality picture than any current High-Def tv station, providing your tv is "Full-HD", sometimes known as "1080p" tvs. All that has no real bearing on your decisions about Freeview terrestrial digital reception next March, but it was necessary to state it at this juncture.

Digital Tips - 2 : Radio (again)

Continuing the theme of Freeview radio, you don't need to have your tv switched on to listen to any of the many radio stations on Freeview if your reception is via a Freeview STB or Personal Video Recorder (PVR). So long as your STB or PVR has "audio-out sockets" (and most, if not all, do), you can connect those sockets to the Auxiliary-IN or Line-IN sockets of your audio equipment. Your Freeview box does need a number display, at least. Radio 2, for example, is on Freeview number 702, so it's easy to punch the number in using the box's remote control.

Of course, if the Freeview box and the audio equipment are a long way apart, you'll need long cables and it may not be acceptable to you to have those trailing around the room. However, I'm going to ignore that and explain just how to set this up as it's the most useful way to listen to digital radio (the sound is better than Digital Audio Broadcasting [DAB]).

The audio-out sockets and the Aux-IN sockets are what are called "Phono" sockets. Here's what they look like:

The white one (sometimes it's black instead) is for the left stereo channel and the red one is for the right stereo channel. You will need to buy a stereo phono cable to connect the equipment together. Here's what the ends of such a cable look like, showing the black and red phono plugs.

The black plugs go into the white (or black) sockets of your STB and your audio equipment and the red plugs go into the red sockets - it couldn't be easier! Just make sure you've measured how long the cable needs to be and buy a cable of at least that length - goes without saying!

What to do about Digital - 2 : Buying a Freeview Set-Top Box (STB)

If you currently have an analogue-only television set and have not embraced the digital Freeview tv service at all, you will lose all your favourite television programmes next March if you do nothing. The simplest thing to do is to buy what is called a "Freeview Set-Top Box", or just an STB, for short. This will work with your current tv aerial and sit between that aerial and your tv set. See "What to Do About Digital - 1" for more information about this.

How do you choose a Freeview STB then? You can either investigate what's available on the internet or visit a local tv shop. Let's look at what you'll find. If you put "Freeview Set Top Boxes" into Google it will return nearly two million "hits": somewhat daunting! Some of the hits will be reviews and some will be offering STBs for sale. Go into a local tv shop and you'll probably have less choice, which is more workable, but do go into several shops because they may well stock different manufacturer's products.

You may well decide on a maximum price you're prepared to pay. As your tv is old and probably of the old bulky cathode ray tube (CRT) design, you aren't interested in High Definition (HD). That will keep the cost down. You could well come away with a box costing under £30.

You will need to know one thing before starting this exercise: does your tv have a Scart socket?
Here's what one of those looks like on the back of a tv:

If your tv has at least one of these, you're fine. If not, when you seek a Freeview STB you'll need to ask for one "with an RF modulator inside it". Those are the words to use. They are more expensive, possibly £60 to £70, and there are very few of them available. You will then be able to "play" the STB through your aerial lead connecting the STB to the tv (see "What to Do About Digital - 1") and use one of the numbered buttons on your tv and/or remote control to tune the tv to the STB. Your sound will be in mono and not stereo but your tv may be just mono anyway.

If you are able to buy one of the cheaper STBs because you can connect it to your tv using the Scart cable provided with it, then stereo sound will be heard if your tv is a stereo one.

What else do you need to look out for?
Firstly, if you intend to listen to Freeview radio then it's useful if the STB has a display of at least numbers, rather than just a light (LED) which has one colour when the STB is in standby and another colour when it is on.
Secondly, ask to see the EPG (Electronic Programme Guide). That's a way of finding out what programmes are on all stations for seven days ahead. Some of them are easy to follow, some are a pain. Make sure you can navigate that with the remote control easily before you decide on a purchase.
Thirdly, and this may no longer apply, a few years ago there were several STBs for sale which had a faulty component inside. This resulted in a few seconds of silence every ten minutes or so. Sometimes the silence would actually last for ten minutes and then return: not very helpful. The way round the long silence was to quickly change station and then go back to what you wanted to watch: not something you really want to keep doing. It's worth asking in the shop if the STB you finally choose is without that fault, but do give it a good test once you have it up and running in your home.

Finally, any good tv shop will install an STB for you, free of charge (you have bought it from them, after all). Do watch the way it's installed and where all the cables go. If at any time you have to disconnect it (decorating, etc) you need to know how to put it all back because you can't expect the shop to do that all again for nothing - they'd make a charge. Making a diagram at the installation time is a good idea.

If you live in a poor reception area, it's better to wait until next March before buying a Freeview STB. You will then be able to test it on the new, stronger transmissions. If you do decide to buy it before then and, once installed, you cannot receive anything, don't be swayed by any suggestions of a new aerial being needed or a booster (amplifier) on your existing aerial being required. That may not be needed next March - just be patient: you don't want to spend money unnecessarily, do you? See what happens in March - if you still cannot receive the digital signals, then you will need advice and I may be able to help with that, so long as you are a Wimborne U3A member.

Mendip Transmitter Changes : 2011 - 2013

Although the Mendip transmitter experienced its Digital Switchover in March 2010, there are still changes yet to come as a result of other areas having their DSO plus the selling of channels to mobile phone companies for the new 4G network.

There will be three further changes in 2012 and one in 2013, none of them requiring a rescan.
29 February 2012 - CHANGE: A rescan will be required on 28 March 2012 and again in 2013, date to be advised when known.

What to do about Digital - 1 [Installing a Freeview Set Top Box]

This is the first in a second series of posts on this site to help you with the Digital TV Switchover at the Rowridge and Winterborne Stickland tv transmitters next March.

I know some of you who currently have only analogue television reception are beginning to think about what to do about digital. Here are some initial thoughts - more will follow in subsequent posts under this heading.

You can continue to use your current analogue tv. You will, however, have to add what is called a "Freeview Set Top Box" ("STB"). These are available from all good television shops plus other outlets like supermarkets, discount stores etc.

This STB will usually come with an "aerial fly-lead". Your current aerial lead going into a socket on the back of your tv has to be taken out of that socket and plugged into the "aerial input" socket on the STB. The aerial fly-lead given with the STB then is connected between the "aerial output" socket on the STB and the aerial socket on the tv. There are different plugs and sockets used so you cannot go wrong - just look at the plugs on the ends of the aerial fly-lead and the sockets on the equipment and you'll see how easy it is.

The STB should also come with what is called a "Scart Lead". This is quite a beast of a lead with a large plug on each end. It has to be connected between the "TV" Scart socket on the STB and a Scart socket on the tv, usually called "AV1" or "IN-1". If you have some other device connected to the tv by a Scart lead already, that socket will most likely already be used, so you'd have to use another Scart socket on the tv for your STB.

If you qualify for the Digital Switchover Help Scheme (essentially over 75 years of age or on some form of benefit), you can apply for that help from September onwards, up to one month after the final Switchover date (March 21st). Or you could buy an STB at any time, but do ask very near neighbours if they can receive digital terrestrial (Freeview) tv (not satellite) successfully. Otherwise, if you cannot receive it now you would be wasting guarantee time on the STB by buying now. Reception after the Switchover will be much better than now so it may be better to wait until close to March 7th before buying an STB.

Certainly if you are watching your analogue tv from the Winterborne Stickland Relay transmitter, there is no point in buying an STB yet because there are no digital transmissions from that transmitter until next March.

The next post in this series will look at possible problems with buying and installing an STB - there are a few! Guidelines will be given about possible ways of overcoming those problems, but the basic message behind this first post is:
You do not need to buy a new tv, nor do you need a new aerial (assuming your analogue reception is currently all right). Here is a LINK to explain more about the Switchover Help Scheme.

Digital Tips - 1 : Radio

It may seem strange to have an item about radio on a tv site. However, this site has an aim of clearing up any possible confusion. The analogue FM radio service will not be switched off next March. There has been some confusion about this. A short while ago the Government stipulated a target date of 2015 for switching off the FM radio service. This has now been withdrawn and there is no current expected date. The only certainty is that analogue FM will be switched off in the future, at some time, probably later rather than sooner.

It may be appropriate to point out that listening to analogue FM radio still means you are listening to digital radio. Between studio and transmitter the signal is digitised, at a slightly lower quality level than CD. It is returned to the analogue domain for transmission.

It may also be appropriate to say that when listening to the stereo sound of analogue tv (NICAM stereo) you are actually listening to digital audio. It is only the pictures which are analogue, unless you are watching an old pre-NICAM stereo tv where the sound is carried by the analogue mono transmission.

Watch out for future "Digital Tips" on this site.

2013 Possible Problem

In 2013, a part of the tv transmission spectrum that was used by analogue TV will be auctioned off to mobile phone operators to use for the next generation of mobile Internet services, known as 4G. This will allow for an increase in data speeds on the mobile phone network, in order to make internet access by mobile phone much quicker. The problem is that many TV aerials do a good job of picking up signals in that band and, if those signals are amplified by a signal booster, the interference from neighbouring 4G base stations could overload the tuners in Freeview TV sets and set-top boxes.

The part of the transmission spectrum to be so used is channels 61 to 68. These are well beyond those used by the Rowridge transmitter but they are part of the current Mendip transmitter range of digital channels. Some change to the channels used by Mendip will be necessary by 2013, therefore. Anyone who receives from Mendip and who has an aerial amplifier should watch out for possible problems once this new 4G service starts up within the area in which they live.

If a problem does occur, there will, by then, be an Ofcom contact to whom to report the problem. A filter can be inserted between the aerial lead and the tv/set-top box. The current recommendation is that the phone operators foot the bill for this. That filter may not be effective, however, for anyone living very near to a 4G telephone transmitter. In such an instance, either cable or satellite is the only currently foreseen answer, but who pays for that is not yet clear.

For anyone interested in following this up further, here is a link.

Digital Switchover Experience

In the Saga Magazine of June, 2011, there is a letter on page 205 which gives cause for concern. The writer, a pensioner, lives at Wisbech, in Cambridgeshire, and has just experienced the Digital Switchover for the East of England. She explains that she and her husband were horrified to find that they'd need to have their aerial changed as well as either buying digital boxes for the television sets they'd had for years, which were still going strong, or replacing the sets with Freeview ready models.

What is not explained is their source of this information. The main function of this blogsite is to ensure that all our Wimborne U3A members have access to fully correct and relevant information about the south of England Digital Switchover next March (2012). The couple in Wisbech are correct in that they need a digital box for each of their televisions (available for between £20 and £30 each). They do not need to buy any new televisions.

There can be very old televisions which require a special way of connecting to a digital box, and may even require a special kind of box. If any of our members is concerned about that, please contact me (Colin Moore) directly by phone or e-mail (details on the back of every Newsletter).

The most disturbing part of the letter concerns the advice that a new aerial was needed. It appears from the letter that they have already had a new aerial fitted, at a cost of more than £400.

To start with, that is an excessive cost for changing an aerial. Secondly, most people will not need a new aerial anyway. The simple test is: what is your current analogue picture like? Is any channel producing a snowy picture (small white dots all over)? If that's the case, it's most likely Channel 4 will be the worst and BBC-1 the best picture, if using the Rowridge transmitter. The reason could be the position of the house or even the position of the aerial on the house. It could be the cable from the aerial into the house and not the aerial itself which is the problem. If having a contractor in to deal with an aerial problem, do ensure all other avenues have been exhausted and have several estimates, comparing what each contractor says is necessary, and use our advice line to seek a second opinion on their estimates.

If the analogue reception is good (not snowy) then digital reception, after the Switchover, should not require a new aerial. You should not take any action regarding aerials until the Switchover has started because the current transmissions are much weaker than they will be then.

Everybody's situation is different. Do take advice before committing to any expense.