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>> 3D sound ‘zooming’ both of which could be a good idea – if sensibly used. There is also built-in 2D-to-3D conversion where one can hope for miracles but, probably, it has not happened yet. Another major 2011 event was the approval or the second DVB 3DTV standard, known as DVB-3DTV Phase 2a which allows both 2D and 3D versions of a programme to be broadcast within the same video signal. This ‘service compatible’ system means that new ‘Phase 2a’ 3D TVs and STBs can receive 3D programmes while existing 2D HDTV receivers and set- top boxes can deliver the 2D version. Without a spectacular rush to the shops filling every home with 3D sets, 2011 still showed significant growth in 3DTV sales Active or Passive? it’s a walk-over! by Robin Palmer W ith the forthcoming Olympics being broadcast in 3D free-to-air, there is sure to be a surge in new TV purchases. Given so many 3D capable models to choose from, which is best? Until the manufacturers come out with autostereoscopic designs that work properly in high definition, we have to view 3D though some sort of glasses to separate the left and right images when viewing a 3D TV set. For home entertainment, there are only two main choices: active or passive glasses. Active 3D glasses use an electronically sequenced shutter to alternately blink each eye in synchronism with the display showing left and right images in quick succession. This is possible because plasma and modern LCD panels are capable of very fast switching so can create left and right images within the timespan of a single television frame. It costs the manufacturer little more to make a 3D-ready set than a 2D model with 100/120 Hz refresh.  The down side is that the active glasses are expensive because they need 34 | TV-BAY MAGAZINE and more programme making. In the UK at least, there is now a growing core of TV and film professionals with 3D training and experience, and the number of Sky3D subscribers is increasing, but Sky won’t say by how much. There are also more 3D broadcasts now available. 3D was certainly not broken in 2011, nor was it ‘made’. Expect continued growth in 2012. two high-speed LCD shutters, the associated drive electronics and some kind of wireless receiver for the sync signal, plus a battery. They are also relatively bulky. With passive 3D glasses system, the extra cost arises in the LCD panel manufacture. (This technology is not suitable for plasma panels). In a 3D LCD, the screen polariser has a layer of alternating strips of left and right handed filters that are accurately line-up with the display line structure. Viewed in 2D with no glasses, this makes no difference to the viewer. Passive 3D glasses have low-cost left and right hand polarisers that filter out the images which are vertically separated by the TV’s display filters. So here the set is more costly and specialised to make but the glasses cost almost nothing compared with the £50 to £100 per pair charged for active types. This is why new 3D active sets come with one or two pairs in the box. With passive glasses, you might get 10! But technically which is best? Active shutter systems give the full vertical resolution and you do have a choice of plasma as well as LCD technologies. However, modern LCDs are just as good as plasma and the loss of vertical  resolution with passive glasses is not really apparent in normal viewing conditions.  Motion portrayal can be noticeably better with passive glasses. Then there is question of brightness. With both systems each eye is only seeing roughly half image and through a light reducing filter. So both are about the same or slightly less for shuttered. Some people report that flicker is annoyingly visible with active glasses. When you add in the cost of three or more spare sets of active glasses to the price of the set, an active model is more expensive. If you want the cheapest initial purchase, if you have no friends or family, if you are never going to lose or break your active glasses, if you don’t mind the batteries going flat, and if you are not going to take them round to a friend’s house and expect them to work there too, then go for an active system. However if you want to share the 3D viewing experience with visitors and not worry if they walk off with or sit on your £1 glasses, then go for a passive 3D TV set. Perhaps LG. Robin Palmer is Managing Director of Cel-Soft and is currently involved with software solutions for 3D & TV quality control and measurement technology.