High-definition television, abbreviated as HDTV, delivers a high-resolution picture that is vastly superior to non-HDTV, or standard sets. At a frequency of two megapixels per frame, an HDTV provides an image two to five times the quality of a standard TV set. The advances in HDTV technology over the past two decades have led to an increased demand; as such, there are many products from which to choose.
After a brief look at the history of and technology behind HDTV, a buyer will want to learn the various features and functions, including the difference between plasma and LCD screens, interlaced and progressive scanning, and HD signal delivery. Upon determining which sets meet their needs, buyers can purchase their HDTV online at eBay.
History of HDTV
In the 1930s, the first high-definition televisions emerged as improvements to earlier systems. With just 30 lines of resolution, the non-HDTVs were based on mechanical systems rather than digital systems. In 1936, England began testing HDTV service with both mechanical and electronic systems. Two years later, France implemented its own tests, delivering a 441-line system which gained popularity in other countries. An 819-line system debuted in 1949 that, although monochrome, still qualifies as high definition, even compared to today's technology. Color broadcasts debuted in the United States in the early 1950s, with resolution as good as their monochromatic predecessors. It would be 1960 before European sets followed suit.
In 1964, the Japan Broadcasting Corporation began TV research with the goal of "unlock[ing] the fundamental mechanism of video and sound interactions with the five human senses." In 1972, the 1,125-line NHK Color became available, providing a 5:3 aspect ratio and 60 Hz refresh rate. By the end of the 1970s, four models of high-definition televisions were available, two color and two monochrome.
As the 20th century wore on, electronics companies tried to outdo each other, each seeking to create a TV with higher definition than the one before it. In 1990, Europe delivered the first HDTV transmissions with its coverage of the 1990 FIFA World Cup, broadcast in eight Italian cinemas and eight Spanish ones. HDTV technology made its American debut in 1996 with its first public HDTV broadcast. In 2000, 525-line sets became the new standard, with high-definition now regarded as televisions with 625 lines and above. By 2010, more than 200 commercial channels carried high-definition images from 185 million HDTVs via satellite. The United Kingdom was the first country to deliver high-definition content via non-satellite means.
There are three considerations for HDTVs: frame size, frame rate, and scanning systems. The first parameter, frame size, is derived by multiplying the number of horizontal pixels by the number of vertical pixels. The number of video frames per second is known as frame rate. The scanning system refers to the way the picture is delivered to the screen; progressive and interlaced are the two available options, with 720 pand 1080 ias industry standards. For slow-moving or still images, the analog-based interlaced is sufficient; high-speed video, however, is best viewed with progressive scanning, as computer-generated images generally have a better appearance with this system. As such, progressive offers a clearer picture than interlaced, yet most HD programming is displayed at 1080i. No standard of HDTV color support presently exists; however, pixel colors today can reach up to 30 bits, which breaks down into 10 per primary color: red, green, and blue. This translates into a palette of one billion colors. The table below illustrates the three primary HDTV formats.
Progressive Scan (p)/Interlaced (i)
1920 x 1080p
2.1 per frame
1920 x 1080i
1440 x 1080i
1 per field; 2.1 per frame
0.8 per field; 1.6 per frame
1280 x 720p
0.9 per frame
Unless additional bandwidth is available to transmit very high resolutions, a viewer may experience a loss of fidelity, or picture precision. Known as lossy compression, this may result in a distorted picture. For the highest fidelity, the source transmission, field ratio, frame rate, and lines should all be in agreement. Digital cable, land-based broadcast, Sony Blu-ray, and Internet downloads can all be types of high-definition image sources. The recording of HDTV transmissions is best accomplished through digital video recorders, DVRs. It should be noted that recording HDTV streams requires a considerably higher amount of bandwidth storage than that of standard streams.
With resolutions of either 720p or 1080i, high definition is the top resolution offered within the digital television genre. The other two formats, enhanced and standard, provide just 480p and 480i resolution, respectively.
How to Select an HDTV
HDTV sets can cost anywhere from hundreds to thousands of dollars. As such, it is best to know what to look for before making a purchase. The first step is determining what screen size is desired. It should be noted that a set below 35 inches in width generally comes in a resolution of 720; 1080i is standard for HDTVs 40 inches or above. The viewing distance may also be a consideration, as 720p is virtually indistinguishable from 1080i when viewed from afar. With a ratio of 16:9, widescreen delivers an image that is proportionate to 16 inches in width by 9 inches in height. All HDTVs have wide-format screens; therefore, they provide a more movie-screen image than a modified square space.
Technologically speaking, HDTV comes in LCDand plasma screens; although rear-projection models are available, they are less common and vastly more expensive. LCD sets create a screen image by transmitting a bright fluorescent backlight through a layer of liquid crystals. If an LED light is used in place of fluorescent, the set is considered to be an LED TV. Most HDTVs under 40 inches in width are available only in this format.
Plasma HDTVs utilize an electrical charge that pulls ultraviolet light from gas. HDTV sets over 40 inches are available in either format, although plasma is generally less expensive than LCD. Another difference between the two is their display strengths. Blacks are reproduced best by plasma, providing a contrast highly desired in low or ambient lighting, yet LCDs deliver a brighter image, recommended for more well-lit environments. In general, LCDs are thinner and lighter than their plasma counterparts.
Newer to the scene are Internet-connected HDTVs. These enable viewers to watch Internet content directly on their television, such as that provided by video streaming services. Although highly desirable, these sets can cost significantly more than their non-wired counterparts. It may be best to look into a device that, although not directly connected to the Web, can be hooked up to the Internet, such as a Blu-ray player, video console, or dedicated computer.
Of course, budget comes into play when evaluating HDTV options. However, features, benefits, and specifications must also be considered. First, a buyer may want to research brands and model. Size is the next determinant, as this will affect both options and price. The buyer should determine where they will place the TV, including their distance from the screen; this will help dictate the appropriate screen size. In terms of picture quality, a sharper black delivers the best colors and contrasts. Other factors to consider include the number of high-definition multimedia interface (HDMI) connections, the sound quality, ease in mounting or other secure placement in the home, the functionality of the remote, and the added expense of cables. The HDMI connections are worth noting when setting up a home entertainment center, as these are necessary for transmitting uncompressed digital video and audio from HDMI-compliant devices to those with digital audio.
Securing HDTV Signals
Three things go into delivering a high-definition image to your HDTV set. First is the signal itself; this can be provided by such means as digital satellite or cable, and even over-the-air broadcasts. If the latter is selected, some tools are required, namely an HDTV, HDTV tuner, and broadcast signal decoder. Second, high-definition streams are available from most cable and satellite TV providers, with a digital cable TV tuner necessary to receive this content. Third, high-definition digital satellite reception requires both HD-compatible dishes and receivers. It should be noted that cable and satellite HD programming merit an additional subscription cost.
Buying an HDTV
Before purchasing an HDTV set online, some Web research is recommended. The Internet often provides more information than a store, in that a complete list of each model's features and functions is often available online. In addition, digital users' guides can often be downloaded and studied for more extensive information. This often provides a far better means of evaluation than review sites or salespeople.
Buyers may wish to visit a brick-and-mortar store for a visual review of HDTV set options before purchasing online. When evaluating display models in these stores, a consumer should only look at live-action feeds; animated films are designed to be color perfect, so they do not provide a good mode of picture comparison.
Another thing to bear in mind is that store models often do not deliver the best quality picture due to poor or inconsistent adjustment; in fact, they frequently use analog delivery rather than digital due to its reduced cost. Because of this, buyers should ask which type of video distribution is being used. In addition, the extremely bright lighting of most showrooms does not deliver an accurate picture representation, also making side-by-side comparison a somewhat fruitless endeavor. To really analyze picture quality, DVDs or flash drives loaded with photos brought from home facilitate the comparison of both motion and still picture quality. The level of screen gloss will also affect viewing experience, so it will need to be tested from different angles, with the set both on and off.
Buying an HDTV on eBay
While HDTVs can be purchased from a variety of sources, the popular online marketplace eBay is a frequent favorite. With an extensive selection of brands and models, the site provides easy product comparisons and savings. A straightforward search for "HDTV" returns an impressive 40,000 results. Related searches you may wish to consider include "32 hdtv," "flat screen tv," "hdtv 1080 p," "hdtv 42," "hdtv 22," and more. You can also input a price range, or even factors such as new or used models, eBay top-rated sellers, buying formats, and shipping options. You will find that eBay has recommended some popular products, which may include both "Plasma HDTV" and "LCD HDTV" sets. To further narrow returned results, you can search for specific brands, models, and features.
After you have a short list of four or five products, it is time to make your final selection. Here, it is beneficial to examine eBay's sellers, including user satisfaction ratings and eBay Top-rated seller listing statistics. Next, you need to factor in shipping options, as many sellers offer free shipping or even local pickup. If the seller offers returns, investigate the terms, including the time limit and who is responsible for the cost of return shipping.
There are many factors to consider when purchasing an HDTV. Depending on the size and features desired, the set may be a costly investment. HDTVs have rapidly undergone technological advancements in the last few decades, and manufactures are still striving to improve resolution and efficiency. In order to ensure the most entertainment from an HDTV set, a buyer should know exactly what features are priorities before purchasing.
When evaluating HDTVs, two important considerations are size and resolution. Most sets under 40 inches wide come in 920p, or progressive, scanning systems, while those over 40 inches are often made in 1080i, or interlaced systems. A prospective buyer is also advised to learn about frame size and frame rate. To avoid a loss of picture fidelity, these factors, along with source transmission, should be in agreement. Comparison between brands and models follows, which may include online and even in-store review.
A great selection of HDTVs at the varied prices can be found online at eBay. eBay encourages high levels of customer service through its seller feedback system, so buyers can be confident that they are buying their products from reputable salespeople focused on creating an easy and convenient shopping experience.