Introduction to HDTV
The availability of a wide range of extremely high-quality sources of digital video, and audio, signals has heralded the arrival of a television receiver in keeping with the new technologies – and, indeed, perhaps the most significant advance in television technology since the introduction of colour, way back in the 1950s – the HD (“High Definition”) TV. An HDTV offers not only a larger screen size – more suitable for the “home theatre” environment, now so popular with many domestic electronic consumers – but a picture quality that is many times higher than the traditional, CRT (“Cathode Ray Tube”) alternatives. Concern has been expressed, in the past, however, that some flat panel television sets have been marketed as “HD Ready”, when, in fact, they are not – so it’s worth taking some time to examine the technology, and the essential features, which will allow you to make an informed decision when it comes to purchasing an appropriate HDTV, for now, and for the future.
HDTV Technology
The essential components for an HDTV system are an HD receiver, either as an integral part of the set itself, or as a separate, “set top” device, and an “HD Ready” display, usually in the form of an LCD (“Liquid Crystal Display”), or Plasma, screen.
Unlike conventional television sets – which create an image by firing electrically charged particles (electrons, originally known as “cathode rays”) at the screen – neither LCD, nor Plasma, TVs, require a CRT, and, as a result, are significantly thinner and more lightweight.
Liquid Crystal Displays, as the name suggests, are composed of crystals suspended in a liquid, and it is the behaviour of the crystals, under an applied voltage, which determines whether light passes through, or not. This allows the individual picture elements, or “pixels”, in an image to be switched either “on”, or “off”, thus appearing light or dark.
The main advantages of LCD over the completing, Plasma, technology, are, generally speaking, that it produces brighter images, runs at a cooler temperature, and has no issues regarding operation at high altitude, nor the so-called “burn-in” of static images.
Plasma technology, on the other hand, produces an image via enclosed cells of charged, plasma gas. Contrary to what you may be told, perhaps, by over-zealous, LCD salespeople, the plasma gas is completely sealed within the unit, and never (that’s never) needs to be replaced. Another popular myth is that Plasma TVs suffer from short life spans – in fact, typical life spans, of 30,000 hours, or so, equate to eight hours’ viewing time, every single day for over 10 years.
In reality, the advantages of Plasma over LCD include the fact that Plasma screens in larger sizes (40 inches, and above) are more economical to manufacture – and therefore cheaper to buy – and that contrast ratios and colour rendition are higher and more accurate.
The debate continues to rage as whether LCD or Plasma is the better of the two technologies, but, quite frankly, market forces – driven by increasingly sophisticated consumers – have led to a convergence, or coming together, of the two technologies, in terms of quality and functionality. Excellent models of both types are now readily available, and the final decision is largely subjective.
Other Considerations
The resolution of an HDTV is a measure of the picture quality that you can expect, and is usually quoted as the “rows x columns” of pixels that form the displayed image. You may, for example, come across figures like “1920 x 1080”, or “720 x 576”, and – all other things being equal – the higher the resolution the better. Bear in mind, however, that HD devices – to be HD – must have a resolution of, at least, 720 physical lines. Remember, also, that true HD resolution cannot be achieved by Plasma TVs smaller than 50 inches. The LG 60PY2R model, for example, is a 60-inch Plasma TV, with a resolution of 1366 x 768 pixels.
The so-called contrast ratio is the ratio between the intensity of a pixel that is fully “on” and one that is fully “off” – between the whitest white, and blackest black, in an image if you like. Once again, the higher the contrast ratio, the better. The Philips 42PF9631 model, for example, is a 42-inch Plasma TV, with a contrast ratio of 10,000:1.
The aspect ratio is the ratio of the width of a displayed image relative to its height. Conventional television sets, for example, have an aspect ratio of 4:3 – but any device that claims to be capable of displaying true widescreen must have a corresponding widescreen aspect ratio, of 16:9. The Sony KDL52X2000U, for example, is 52-inch LCD model, with 16:9 aspect ratio.
If you’re intending to connect other devices, such as cable and satellite boxes, DVD players, computers, or games consoles, you’ll need to check that a set has the correct input and output options – which commonly include composite and S-video, RGB, and, in the latest models, FireWire, DVI (“Digital Visual Interface”) and HDMI (“High Definition Multimedia Interface”). These latter, digital, connections offer the highest video quality. The Panasonic TH42PX60B, a 42-inch Plasma model, and the Samsung LE46M51BX, a 46-inch LCD model, for example, both offer HDMI digital connectivity.
Conclusions
Fancy specifications, glossy sales literature, or sales patter are no substitute for what you see with your own eyes – so try to look, with a critical eye, at as many different models, of both types, as you can, before finally deciding on one.
Think, too, about the features that are of absolute necessity – to you – and those that are not; some of the advanced features are all very well, but if you are likely use them infrequently, or never, then perhaps they can be dispensed with. Additional functionality, after all, usually requires additional budget.
Finally, as with any popular technology, there are some – less scrupulous, shall we say – manufacturers, who are all too keen to “jump on the bandwagon” – offering “rock bottom” prices, but, unfortunately, quality and technical support to match. Avoid these “here today, gone tomorrow” merchants, and buy from a manufacturer with a proven track record.
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