HDTV History

Part 1: The History of HDTV and Changing Needs

It has been nearly 80 years since the first public demonstration of television took place in a crowded laboratory in London . Since that time television has advanced from blurry black and white pictures to stunning high-definition images with life-like depth and realism. How were these achievements made? More importantly, what should we expect in the future as we approach television's first centennial?

A Look Back

Today, there are more than 220 million televisions in the United States . These TV sets have their historical roots in technology that was pioneered in the late 1920's and 1930's. While many television milestones took place during these years, it was not until 1949 that sales of new sets really started taking off. In 1953, the NTSC (National Television System Committee) standard was adopted for the transmission of color television and in 1954; RCA launched the first commercially available color TV. The 1950s also saw the beginning of a shift in television architecture, moving away from vacuum tube chassis to more solid state components.

During the 1960s, the transition from black and white TVs to color was largely completed. Other advancements during this decade included "HiFi" TV sets and widespread popularity of remote control units. In the mid 1970s, the advent of the VCR transformed the television experience with the ability to record and play back videotapes. The 1970s and 1980s were a time when many Americans took down their unsightly TV antennas and replaced them with cable TV boxes, offering a score of channels to flip through. The so called "MTV generation" was born into this era when television was no longer just a family entertainment center, but the center point of personal and generational expression. While it would be unfair to say that the ensuing years have been technologically dormant for television, few would argue that the next major milestone in TV history was the advent of high definition television (HDTV).

The Early Years of HDTV

Modern-day HDTV has its roots in research that was started in Japan by the NHK (Japan Broadcasting Corporation) in 1970. In 1977, the SMPTE (The Society of Motion Picture and Television Engineers) Study Group on High Definition Television was formed. The group published its initial recommendations in 1980, which included, among other things, the definition of wide screen format and 1100-line scanning structure. The first demonstration of HDTV in the United States took place in 1981 and generated a great deal of interest. In 1987, the FCC (Federal Communications Commission) sought advice from the private sector and formed the Advisory Committee on Advanced Television Service. Initially, there were as many as 23 different ATV (Advanced Television) systems proposed to this committee, but by 1990, there were only 9 proposals remaining - all based on analog technology. However, by mid-1991, the leading ATV designs were based on a new all-digital approach. A joint proposal from several companies detailing an all-digital ATV system was given to the FCC in 1995. Following certain changes and compromises, this proposal was approved by the FCC in December, 1996 and became the mandated ATSC (Advanced Television Systems Committee) standard for terrestrial DTV/HDTV broadcasting.

HDTV Today

After 35 years of development, high definition television has finally started making inroads in the consumer marketplace. Today, you hear a lot of HD buzzwords like: HD Ready, HD Compatible, Integrated HDTV, etc. To help consumers deal with the mounting tide of HDTV-related questions, the FCC created a consumer website http://www.dtv.gov in October 2004. The FCC has also set a timeline for the conversion from analog to digital television (DTV). As it stands now, analog television will cease in the United States on December 31, 2006, but there are many that believe that the FCC will extend this date until the penetration of DTV has reached 85% or greater in most key markets. Those still using old fashioned analog TVs won't be entirely out of luck; the FCC mandate requires that consumers be able to purchase a converter box so that their older analog sets can receive the new digital signals. While these converter boxes should be affordable, they will only output the same low resolution signals that our TVs currently use. If you want to see true HD, you'll need to spring for a fancy new HDTV set, projector or flat panel display.

What is HDTV ?

What is HDTV really all about? What's new, and why is it better? The best way to make a comparison between standard definition television (SDTV) and high definition television (HDTV) is to consider today's popular digital cameras. Some years ago, when digital cameras first appeared on the consumer market, a popular digital camera featured a 1.6 Mega Pixel (Mpix) image sensor. At that time, 1.6 Mpix was considered high quality. Today, one can easily find 5 and 6 Mpix cameras with far better image quality for a lot less money.

In a similar way, HDTV delivers significantly more resolution than SDTV. For example, a 1080i HDTV signal offers about six times the resolution of a conventional 480i SDTV signal. HDTV also features a wider (16:9) aspect ratio format that more closely resembles human peripheral vision than the (4:3) aspect ratio used by conventional TVs in the past. Furthermore, HDTV is based on a system of 3 primary image signal components rather than a single composite signal, thus eliminating the need for signal encoding and decoding processes that can degrade image quality. Perhaps the biggest advantage over the old analog SDTV system is that HDTV is an inherently digital system. If installed properly, digital HDTV can provide the ultimate in pristine image quality, but there are many factors that must be considered, as we shall see.

HDTV in the Home

What do you need to see HDTV? As in any visual system there are three basic components to consider:

HDTV Sources:

When examining possible sources, one must be careful to distinguish between true HDTV sources and those that offer Enhanced Definition (EDTV), the latter being normal (SDTV) video that is scaled or "up-converted" to a higher resolution. While EDTV can certainly provide dramatic picture quality improvements over the original SDTV source, it can never offer the same level of image quality as a true HDTV source.

Examples of true HDTV sources are:

Of f-air ATSC receivers using HDTV Digital cable Set Top Boxes (STB) that of fer HDTV service Digital satellite receivers that of fer HDTV service (i.e. DirecTV, DISH Network, et al.) Windows Media High Definition Video HD-DVD and Blu-Ray DVD players

Examples of EDTV sources are:

DVD players featuring DVI / HDMI outputs (with built-in HDTV scalars) Video image processors (scalers) Digital cable Set Top Boxes (STB) that of fer EDTV service Digital satellite receivers that of fer EDTV service (i.e. DirecTV, DISH Network, et al.)

Another important consideration is analog versus digital sources. As previously stated, the ATSC has adopted a digital transmission system for HDTV; however, there are some HDTV sources on the market today that only offer analog outputs. Analog HDTV sources will become an increasingly greater rarity in a world of all-digital HDTV displays. This is especially true because all newer digital systems also employ HDCP (High-Bandwidth Digital Content Protection) to safeguard digital content against illegal pirating. HDCP cannot be implemented in analog systems.

HDTV Displays

To realize the maximum potential of HDTV, the display must be fully HD compatible. For most users, this represents the biggest challenge and largest expense in their HD migration budget. Picking the right HD display relies heavily on personal taste, while prices vary greatly from under $1000 to many thousands of dollars. Here are a few key points to look for in order to not only insure that your display is HDTV compatible, but more importantly, HDTV optimized:

Wide screen: Your display should be capable of displaying a widescreen (16:9) HDTV image. It should also be able to display a standard (4:3) SDTV image as well.

Resolution: Your display should have enough resolution to faithfully display an HDTV image. For many displays, this means a native resolution (the display's intrinsic resolution) of at least 1280 x 720 pixels. Higher native resolution is better, with so called "full HD resolution" being 1920 x 1080 pixels.

Video Inputs: Your display should have a full complement of both analog video inputs (such as composite video, s-video, and component video) for legacy components as well as digital video inputs (such as DVI or HDMI) for new HDTV and EDTV sources.

Note: HDCP support is a must for all HDTV displays. If you buy a display with a DVI input you MUST insure that it supports HDCP; if it doesn't, you may not be able to view HDCP-encrypted source material from cable boxes, etc on that display! If your display has an HDMI input, you're in good shape as the HDMI standard fully supports HDCP.

In December 2002, an industry consortium of cable multiple system operators and consumer electronics manufacturers sent a Memorandum of Understanding (MOU) to the FCC detailing their plans to implement DTV / HDTV cable systems and related hardware. In this MOU, there was a specific time table to rollout a new generation of displays that feature digital video inputs with HDCP:

480i grade televisions - none.

480p grade televisions - as follows (either DVI or HDMI with HDCP), or 480P Y,Pb,Pr (analog) interfaces:

· With screen sizes 36 inches and above -- 50% of a manufacturer's models offered for sale effective July 1, 2004; 100% of such models effective July 1, 2005.

· With screen sizes 32 to 35 inches -- 50% of a manufacturer's models offered for sale effective July 1, 2005; 100% of such models effective July 1, 2006.

720p/1080i (HDTV) grade televisions - as follows (either DVI or HDMI interfaces with HDCP):

· With screen sizes 36 inches and above -- 50% of a manufacturer's models offered for sale effective July 1, 2004; 100% of such models effective July 1, 2005.

· With screen sizes 25 to 35 inches -- 50% of a manufacturer's models offered for sale effective July 1, 2005; 100% of such models effective July 1, 2006.

· With screen sizes 13 to 24 inches - 100% of a manufacturer's models offered for sale effective July 1, 2007.

Interconnections:

In order to allow sources and displays to work, they must be interconnected, usually with cables of some sort. This sounds simple enough, yet this is the area where most customer installation problems take place. Today, a typical home theater system can cost anywhere from a few thousand to tens of thousands of dollars, or more. Despite the fact that these figures represent a major investment for most end users, typically less than 3% of the total system price is spent on interconnection cables.

It is a regrettable fact that for most people a cable is just that - a cable. However, when you consider that imperfections in these signal "pipelines" can seriously degrade picture quality; cables start to take on a more profound role. Nowhere is this truer than with the DVI and HDMI cables needed to support digital HDTV.

While audiophiles may argue the complex dynamics of ultra-high fidelity esoteric speaker cables, these cables must carry relatively low frequencies, most of which are below 20 kHz. However, with DVI and HDMI signals, data rates of up to 1.65 Gbit/sec. are possible. In the analog world this would be equivalent to 165 MHz which is more than 8,000 times higher frequency than most audio signals. For short cable runs of less than 5 meters (16.4 ft.) there are usually not too many issues; however, these high frequencies pose serious challenges for longer length DVI and HDMI cables. In general, the higher the frequencies and the longer the cable length, the greater the likelihood that image problems will occur. For example, at low resolutions a DVI signal might travel 20 meters without signal degradation, but at higher resolutions the same cable could exhibit significant image degradation. For this reason, cable lengths for higher resolution signals, such as 1080p, are usually limited to 10 meters or less. Figure 1 illustrates this problem:



Image of 800x600 screen with a conventional 20 meter DVI cable Image of 1600x1200 screens with same 20 meter of DVI cable

To solve the issue of long digital cable runs and reap the full benefits of improved picture quality, cable manufacturers have made various attempts to improve their cables with mixed results. Here are some key points to look for:

Does the manufacturer offer high resolution, long length DVI or HDMI cables ?

Does the cable use silver plated wires for the high speed TMDS data lines (the wires that actually carry the digital picture content)? At very high frequencies, the signal does not travel through the copper wire; it travels on the surface. The silver plating helps mitigate what are known as "skin effect" losses and limits the insertion loss (i.e. less high frequency attenuation).

Does the manufacturer rely on highly embellished claims that sound more like science fiction than science fact? Do they provide a guaranteed level of performance? More than just a money back guarantee, does the manufacturer make a pledge of performance? If yes, this helps make sure you choose the right cable the first time and avoid hassles with returning substandard products.

What warranty does the manufacturer offer?

What level of support does the manufacturer offer? If you have a problem or an installation question, can you get fast, reliable answers?

These are just some of the important questions that must be answered when designing and installing a new HDTV display system. For more sophisticated systems, you may want to rely on a professional home theater designer and installer. CEDIA (Custom Electronic Design and Installation Association) is an excellent resource for both end-users as well as home theater professionals. You can learn more about CEDIA at: http://www.cedia.net/whatis_cedia/

Whether you decide to "do-it-yourself" or contract a professional, having deeper insight into HDTV's past and present will only serve to further enhance your own HD experience. In Part II of this article, we'll take a closer look at the trends and technology that are shaping tomorrow's HDTV systems - and focus on why these factors are important considerations for today's buyers.