When you power-up your television set on the morning of Tuesday, February 17th, 2009, all you may see is snow. That’s because the Federal Communications Commission in the United States has ordered “over-the-air” analog transmissions off the air. Of course, if you have cable or satellite reception, you’ll get a reprieve and it will be like any other day. With price drops, more and more HDTV or DTV tuner-equipped televisions have been finding their way into homes over the last few years.
Where high definition and analog signals differentiate is the amount of video information that can fit within a certain bandwidth or space of an overall signal. An American standard definition television set using NTSC analog technology is capable of up to 480 interlaced lines, whereby ATSC is capable of up to 1080 progressive or interlaced lines of picture information. The current NTSC video technology utilizes an Amplitude Modulation mode for picture, while sound is presented in Frequency Modulation. Both HDTV picture and sound is in a digital format. NTSC bandwidth is rated at 6 Mhz for one signal, however, within an ATSC signal, broadcasters are able to transmit two high quality 1080 interlaced signals in the same amount of space - or up to six 480i signals. An HDTV receiver is able to pick up 18 different formats, reducing them down to 4 - 1080i, 720p, 480p, 480i. Interlacing consist of two fields where a progressive format uses only one. An interesting factor is that while an NTSC system only allowed for one broadcast television signal, stations were able to make money on the return scan on the interlaced portion of that scan - often in the area of electronic billboards or specialized services. FM radio does something similar with it’s Subcarrier Communications Authority format, often referred to as SCA among engineers and FCC documents.
Theater film is usually rated as 24 frames per second, whereas a progressive television is rated at 60 frames per second. In order for a smooth transition between the different formats, a technique called “3:2 pull-down”, otherwise know as “telecining” in technical jargon. Three copies of a film frame are copied, then two frames are recycled. While this works fairly well, there is a downside known as a “12 cycle judder”, producing a slight jerky image when motion is portrayed. The sixty frames per second is based on the 60Hz produced by alternating current. However, higher-end monitors utilize 120 Hertz Technology producing an image at 120 times per second, reducing or eliminating the effects of judder.
An ATSC MPEG-2 Signal is broken down into three picture elements;
Y=Red+Green+Blue (where “Y” is referred to as “intensity” or “luminance”, sometimes depicted as “white”)
Pb=Blue-Y (both Pr and Pb consists of color information otherwise known as chrominance)
Pixels consist of three colors - Red, Green and Blue (RGB)
EDTV is the Consumer Electronics Association (CEA) marketing shorthand for a format that lies between Standard Definition Television standards, and those of true HDTV. Two methods enclosed in the scheme include 480p and 576p. The television sets with this technology generally fall price wise between SDTV and HDTV. What EDTV accomplished was the elimination of line crawl and motion distortion typical in SDTV applications. As the market is pretty well sold on HD technology, the EDTV stopgap has been fading from the electronics scene.
To understand the development of HDTV, is to go back to the dreamers of the 1800’s. Specifically a French artist by the name of Albert Robida whose series of 1882 sketches were remarkable in showing television’s future as an entertainment, instructional and news media. His drawings depicted large flat LCD-like screens that filled walls with electrical devices below the display. At that time, the cathode ray picture tube had yet to be invented, nor had a workable prototype been demonstrated at that point. It would take a German engineer by the name of Paul Nipkow to create a workable mechanical prototype to show television’s earliest potential, however, Paul would not expand upon his work in television transmission.
Up until the invention of CRT’s, neon lights were used for experimental television display technologies. It would take a 14-year-old Idaho farm boy by the name of Philo Farnsworth to come up with a workable theory of all electronic television transmission and reception in 1921. Philo had been plowing his father’s fields on a cool clear crisp morning in getting ready for spring planting. He had learned about experimental television by mechanical means that had been left by the previous owner of the farm. It was the invention of imagination and dreams. After a great deal of effort by Farnsworth and the money of some savvy San Francisco bankers, a working “all-electronic” prototype was demonstrated on September 27th, 1927. From there, television as we know it was up and running.
Color television technology itself is ensconced in the birth of television. In 1889, a Russian scientist by the name Polumordvinov applied for a patent on a color television system based on Paul Nipkow’s invention. However, Polumordiinov was never able to demonstrate a working prototype. On June 27th, 1929, Bell Labs gave its first American demonstration of its color television system. The encoding device contained a bank of color filtered photocells at point of transmission. On the reception end, three color filtered lights would reproduce the image. According to the New York Times, “the colors reproduced perfectly” in its next day’s edition. Keep in mind, the actual picture was only the size of a postage stamp.
In March 1940, a young CBS engineer by the name of Peter Goldmark was on his honeymoon in Montreal, Canada. Before catching the train back to New York City, his bride and he went to see “Gone With The Wind” on a local movie screen. He had an immediate inspiration - color broadcasting. Although both Bell Labs and an English inventor by the name of John Logie Baird had a brief fling in the development of color, they did not see its importance - Peter Goldmark did! In his hotel room and the long train trip back, Goldmark started scribbling notes on what was needed to bring commercial color to life. The system he devised was a modified RCA broadcast camera that had been retrofitted with a spinning color wheel behind the lens of a camera pickup tube. On the receiver side a similar color wheel was placed in front of the face of the CRT. By synchronizing both the transmitted and receiving ends, a color picture was displayed. The CBS Field-Sequential Color System was a hybrid - the marriage of electronic and mechanical engineering. However, it was incompatible with the new black and white television receivers that were beginning to flood the market. Its main competitor, RCA, was not pleased. RCA lacked color broadcast technology, and it was loathed to pay CBS royalties to participate in its invention. After a private demonstration to CBS Chairman and Founder, William S. Paley, Peter Goldmark announced that CBS had developed marketable color to an NTSC forum in August1940. In 1946, CBS gives a color demonstration to the FCC in Nyack, New York In October 1950, the FCC gives CBS the go-ahead to commercialize it’s color system. On June 25th, 1951, CBS televises a one hour color premier featuring Ed Sullivan and other luminaries. After CBS’s initial announcement to the NTSC, RCA’s chairman David Sarnoff puts his Camden, New Jersey engineers to work on a competing color television system - its goals were to create an all electronic color system that was compatible with black and white transmissions. At the end of June, RCA demonstrates its all electronic system and the fight between color systems intensifies. In October, the FCC suspends color transmissions for duration of the Korean War. On March 25th, 1953, CBS throws in the towel, and concedes victory to RCA, The RCA CT-100 rolls off the assembly line in early1954. RCA was not the first manufacturer to have an all-electronic color television on the sales room floor - that distinct honor goes to Westinghouse by one month. All of the aforementioned developments had to take place before HDTV could develop.
Research for high definition television began its life in the NHK (Japan Broadcasting Corporation) labs in 1970. By 1977, the Society of Motion Pictures and Television Engineers (SMPTE) began its collaborated study into the development on high definition television. The initial report from the SMPTE study group suggested a widescreen display of an 1100 line scanning structure. Previous to that, NHK had developed an analog system utilizing a 5:3 aspect ratio. The system did not launch publicly until the late 1990’s. However, in 1981 the Japanese by that time had already demonstrated their MUSE HDTV System in Washington DC which utilized the aforementioned 5:3 aspect ratio. A duly-impressed President Ronald Reagan got the ball rolling, declaring it “a matter of national interest” in bringing HDTV to the United States. In 1987 the FCC established the Advirsory Committee on Advanced Television Service to advise the FCC on technical and public policy aspects. Twenty-three systems were proposed, including those that were compatable with NTSC standards. During the decision-making a technological breakthru occurred by General Instrument who in 1990 brought the attention to the ATSC (otherwise known as Advanced Television System Committee) that the company had developed the first complete digital tv system. Seven months following that initial disclosure, three more digital methods had been brought to light. By February 1993, an ATSC special committee had analyzed its testing of the various system proposals saying it would no longer consider an analog system - the future belonged to digital. The committee recommended that four all digital systems implement authorized modifications that had been proposed.Testing of these modifications followed. A follow-up review recommended that all four system proponents work together to implement the best ideas of the four into a single package. Incorporated was MPEG compression research by NASA’s Jet Propulsion Laboratory which had been conducted earlier. Compression is what allows more signals to be combined into a smaller bandwidth. This technology would be essential in making digital HDTV possible. The honor of the first American terrestrial HDTV transmission belongs to WRC TV (an NBC o&o) on its HD sister station, WHD-TV 34 on August 6th, 1996 - one little problem, the transmission didn’t make it past the office of the station manager. In retrospect, according to CEA (Consumer Electronics Association) the first station to receive its DTV license was CBS affiliate WRAL in Raleigh, North Carolina on June 17th, 1996. The ATSC was officially adopted by the FCC on Christmas Eve in the same year. The CBS network itself, broadcast its first HDTV presentation with the launch of the launch of the John Glenn space shuttle mission on October 29th, 1998. By May 2001, one million HDTV-capable sets were in the hands of consumers.
Types Of Displays
The original HDTV monitors used CRT displays - first in the 4:3 formats, and later in the now familiar 16:9 version. One of the first plasma tv’s on the market was introduced at the Las Vegas Consumer Electronics Show on January 9th, 2002 - the Hitachi HDT20 UltraVision series. Plasma television displays consist of a multitude of tiny cells sandwiched between two glass panels. The cells hold an inert mixture of noble gases - neon and xenon. The gas in the cells is electrically turned into plasma, which in turn excites phosphors to emit light. Plasma displays are bright, 1000 lux or better. The black level has very low luminance resulting in a more lifelike picture. On older models, 400 watts is the norm for a 50” picture. Newer (2006 - forward) models range from 210 to 310 watts in cinema mode. Current models have an average display life of 60,000 hours where afterwards the picture starts to degrade. The biggest problem with Plasma displays has been one shared with the more traditional CRT models - Image Burn In’s. That occurs when a set is left on a static image too long. Newer models have pretty well licked this drawback. Plasma sets generally run warmer and consume more electricity than similar LCD versions. Prices are traditionally higher as well.
An LCD (Liquid Crystal Display) consists of a color filter, horizontal filter, glass plates with a crystal molecule sandwiched inbetween. Each pixel consists of three sub-pixels consisting of red, green and blue filters. Screen resolution is increased via sub-pixel rendering. In a moving picture, smudging is reduced by a pixel overdrive. There are two typs of LCD displays - passive and active. The pixels are addressed one at a time. The passive matrix display must retain its state between refreshes without the benefit of a steady electrical charge. This type of display was used in personal organizers and older laptop computers. An active matrix display uses thin film transistors (TFT’s) added to the polarizing and color filters. Each pixel has its own transistor, allowing the column lines to access one pixel. All row lines are activated in sequence during a refresh operation. This type of display is used in high definition applications offering quicker response times in producing better imaging. Costs run lower than plasma displays with images looking brighter and sharper. Unlike Plasma, LCD displays have no “burn-in” issues. Problems displayed in earlier active displays consisted of dead or stuck pixels, although newer models have pretty much licked these issues. LCD’s consume considerably less power, run cooler. Some drawbacks include a mura effect (small scale cracks), images are only produced in native resolution, unable to use low resolution due to scaling limitations and lower contrast levels than CRT or Plasma. LCD’s have more limited viewing angles in comparison.
You can find reviews for hd monitors at http://reviews.cnet.com/4244-5_7-0.html?query=HDTV&tag=srch&target=
, as well in consumer ratings publications. Even sites like Amazon and Crutchfield offer consumer reviews.
Set Top Boxes
There sre essentially two types of set top boxes - HDTV Receivers and DTV Converters.
The HDTV Receiver is designed for the older “HD-Compatable” monitors. You may remember them - while they were rated as being able to handle high definition signals, the HD ATSC tuner was not included. The sets were high-priced with an analog tuner, but had ports for the hookup to a pricey external box which consisted basically of an external chassis with an ATSC tuner. For most applications the receiver boxes are passé, however, they are still very much needed to receive high definition signals for front/portable projection units. Samsung is a preferred brand.
The DTV Converter Set Top Box is a different, but similar animal. The converter box is an inexpensive cousin to the ATSC receiver. However, instead of injecting a high definition signal into the tv set itself, the box converts the ATSC signal into an analog mode, allowing it to be processed into an older conventional set’s tuner with an output on either channel 3 or 4. Usually the boxes give you a choice to send the signal via an RF antenna connector, or simple rca video and audio jacks. Some additionally offer left and right audio output jacks for input into a stereo receiver or amplifier. Like HDTV receiver boxes, the converters usually include television program listings. One note, any television you buy in the United States today will already have a digital tuner built-in, even if the set is not designated as high definition. What makes them great, is they will work with television sets as early as those made towards the end of World War II. Zenith, an LG Electronics brand makes a very popular model known as the DTT-900.
Digital TV Converter Box Program
The United States Digital Transition and Public Safety Act of 2005 requires the FCC to order the shut down of analog terrestrial (over-the-air) television transmissions by midnight February 17th, 2009. Some television stations in a few markets have already ended analog transmission, some are expected to follow as the date draws near. In order to do that, the NTIA (National Telecommunications and Information Administration is in charge of a program that issues $40 coupons to offset a cost for the boxes. There is a limit for two per household. By filling out an application at https://www.dtv2009.gov
, the NTIA will send you a coupon that you can use at NTIA authorized stores around the country. You can find a list for approved stores through the site or at http://www.mall727.net
at the bottom of the HDTV & Home Theater Page. The coupon program will end on March 31st, 2009
The set top boxes that are approved for the NTIA Coupon Program are as follows;
ALPHA DIGITAL AT2016
APEX DT250 *
Access HD DTA1020D
Access HD DTA1020U
AccessHD DTA1030D *
Artec T3AP Pro *
CRAIG Electronics International Ltd. CVD506 *
Channel Master CM-7000
DIGITAL STREAM DSP7500T
DIGITAL STREAM DSP7700T *
DIGITAL STREAM DTX9900
DIGITAL STREAM DTX9950 *
DIGITAL STREAM DX8700 *
DISH NETWORK TR-40CRA by Dish Network *
DISH Network DTVPal *
Insignia NS-DXA1-APT *
Magnavox TB-100MG9 *
Magnavox TB100MW9A *
Magnavox TB110MW9 *
Memorex MVCB1000 *
Philco TB100HH9 *
Philco TB150HH9 *
RCA DTA 800B
RCA DTA800B1 *
SUNKEY SK-801ATSC *
Winegard RCDT09A *
ZINWELL ZAT-970A *
Zenith DTT901 *
(*Denotes Models With Analog Signal Pass-Thru)
If you’re thinking of using telescoping antennas or “rabbit ears”, forget it, passive or amplified, they rarely work with digital signals. If you are using a “yagi” design either on your roof or in the attic, those will generally work well. Other antennas specifically designed for ATSC signals are worth a look. Prices range from $20 for a “Silver Sensor” (put out under Gemini, Philips and Zenith brand names) to the more expensive models at $100 or greater, including a bow-tie vertical or specialized multi-path antenna. There are many models designed for specific applications.
Another vital area to consider is coax cable. The job of a coax is to deliver a signal from an antenna to your receiver. The more “lossy” or electrically resistant a cable is, the less signal gets to your set, the less your set has to work with to decode that signal. A good brand to consider is THX-rated Monster Cable. Its also the brand to pick in splitters.
Amplifiers are another consideration, especially for fringe reception areas. Here you have to be just as careful. There are many brands out there that really add very little in the way of amplification. One of those exceptional products that does is made by Motorola. The model 484095-001-00 is used by professional cable installers in critically weak signal areas.
There is a site that will tell you what digital television signals you can expect to see in your area at http://www.antennaweb.org/aw/welcome.aspx
. By filling in some basic information, the site will tell you which antenna would likely be your best choice as well where to aim the antenna.
Finally no matter what electronic or electrical product you plug into an a/c outlet, always consider using a good surge protector - Tripp-Lite and Monster are two top-rated brands. Its good insurance - and cheaper than questionable extra-cost “extended coverage” warranties.
By switching to digital television transmission, new bandwidth will open up for public safety communications such as police departments, rescue squads and other public services. It will also enable the FCC to auction spectrum space to various companies such as those offering wireless broadband services. For the viewer, it means “ghost-free” viewing. More viewer choices with the addition of sub channels within the main carrier signal. Better sound. The downside is with ATSC digital transmission, you either get the signal or you don’t. Canada is also expected to switch off its analog television transmitters on August 31st, 2011, according to the Canadian Radio-Television & Telecommunications Commission. Exception will be made in remote areas where analog transmissions are not expected to cause interference.