TV DX is the way a television signal is projected through the airwaves. It's an important component of modern day television, for without it, many countries who have yet to perfect cable transmission underground would not be able to reach millions of home viewers with a television. Reception of the TV DX signal happened by accident and continues to this day to surprise the unsuspected viewer who catches a glimpse of a foreign land's television programming.

February 1938 brought forth the first interception of a foreign land's television signal. The RCA Research Station in New York picked up a trans-atlantic signal from London. While checking the area for various local signals, the station picked up a live telecast of a BBC station's soap opera. Even the BBC logo was evident on the broadcast proving that, indeed, what the researchers were viewing was from England. Since the researchers were recording at the time, they recorded the soap opera and it's been archived today as one of the only pre-war British television productions that survived.

When World War II began in 1939, the BBC suspended TV DX transmissions. This limited the capabilities of researching into the signal reception of television and FM signals involved since the whole world was on the brink of destruction. When the BBC began to transmit again, in 1946, countries as far away as South Africa picked up on the signal almost as soon as the BBC flipped the switch and began transmitting. This became a concern for the United States, who knew that any type of transmission being sent on that frequency had the potential to be picked up by anybody else in the world. This was the same reason the BBC suspended transmission during the war, they didn't want communications to be intercepted by the wrong hands.

This type of transmission triggered the United States Federal Communications Commission (FCC) to allocate a particular band for TV DX transmissions. This was both to limit the range of transmission as well as to prevent other transmissions from interfering. Since interference can lead to problems with communications as well as entertainment, limiting the scope of transmission band was the easiest way at the time to prevent problems from arising. The FCC limited transmissions to 42 to 50 MHz for broadcasting. However, even though limiting the band frequency was theorized to stop interference, it soon became apparent that this wasn't going to be enough. TV DX and FM radio station signals from as far away as 1,400 miles were cross-referencing with local signals in sporadic areas. While this only happened once in awhile, usually when the weather acted up, it soon became a problem for local stations who had to take calls from viewers who couldn't watch the nightly news.

By 1945, the FCC changed the band that FM would need to broadcast on to 88 to 108 MHz. It seemed that, officially, the changes were made because of co-channel interference, atmosphere effect on signals and the current range of coverage as television expanded through the country. While this improved the strength of signal in many areas, problems still arose when the weather took a turn for the worse. No matter what you do to prevent crossing signals, it's bound to happen.

TV DX hit a world record in 1957. One particular signal was picked up more than 10,000 miles from its initial broadcast point. England's BBC was picked up in southern Australia. Since then, signals have triangulated from all over the world and viewers have surprisingly picked up on the invasion on their televisions. Throughout the world, everyday, signals are crossed all over the place.

As long as TV DX is broadcast through the air, viewers will be exposed to the cross-interference of two or more television signals. As more companies opt to broadcast their signals through coaxial cables in local areas through a central hub that later connects to a larger one with a production signal, viewers will be exposed to this interference. When you send a TV DX signal through the air, there's no telling where it will end up. The next time you come across a television show that just doesn't seem right, you might be in the middle of trans-continental television signal getting misplaced.

TV DX refers to the long-distance projection of a television signal. While TV is the short-hand form for television, DX is the telegram term for long distance. Therefore, TV DX is the search for distant television signals, stations and projections through the atmosphere. Generally, these types of signals travel through the tropospheric atmosphere through heavy weather conditions, like wind, snow and rain. Often these signals drop out, are lost or never make it to their destination in tact after the distortion the weather and atmosphere cause to the signal from its source.

Normally, television signals are limited to their area of reception. Forty to one-hundred miles is the accepted cut off point for the projection of television signals. During good weather conditions, these accepted levels rise anyway from fifty to seventy-five percent of what they would be in the worst conditions. In many cases, and based on circumstances, television signals can be reached thousands of miles away after long periods of times on anything ranging from a basic transmitter to a satellite dish in space.

Weather plays an important part in maintaining a steady television signal. Since most reception is based on satellite positions and the signals traveling through the airwaves, weather conditions play a key role in making sure the signal stays strong. Everything from cell phone reception to Internet connections are affected by bad weather in an area, even bad weather fifty miles away can affect signal. During powerful snowstorms and windy conditions, signal loss occurs more frequently interrupting television reception both for local stations and individual homes.

The troposphere is what gives television signals the most problems. The Earth's troposphere extends roughly 25,000 feet from the surface. Warm weather, too, can affect the strength of television signals. It usually will intensify snowy TV signals and improve the signal strength. In other cases, warm weather television signals will intensify to the point that two channel signals will cross and you'll get what's called a co-channel interference. Co-channel interference is when two signals merge and transmit to your television. Often sound, picture and clarity will all be blurred together in one mangled mess that you'll be muting as soon as it occurs on your screen. When weather conditions are perfect, that is it's a clear day out, television signal strength will increase in range and be picked up well beyond it's normal scope of reception.

Those clear days improve the signal in just range. An inversion at the horizon during a clear day will actually curve the signal going to a satellite before bouncing back to the Earth, intensifying it. This, too, increases the range. Fog, surprisingly, makes a television signal stronger. TV DX is affected very well by fog, increasing the range by more than seventy-five percent per cubic foot of fog in a given area. A large field of fog, densely-packed, forcing a clear sky above allows for a smooth signal transfer between areas or between the Earth and a satellite.

Fog also produces good tropospheric results, again due to inversion effects. Fog occurs during high-pressure weather, and if such conditions result in a large belt of fog with clear sky above, there will be heating of the upper fog level and thus an inversion. This situation often arises towards night fall, continues overnight and clears with the sunrise over a period of around 4–5 hours.

In most conditions, TV DX signals are received by local stations that are intended to receive the broadcast from a central location. These stations have large satellite dishes reinforced by smaller dishes around the area that focus on the main dish to maximize the signal coverage. The use of antennas can increase the signal reception strength, which is why many local stations will covet one main satellite dish and then surround the area with smaller ones, sharing the main satellite dish for broadcast and reception purposes.

TV DX signals are an important component of television. No matter whether you subscribe to digital cable or just watch the local channels, a strong TV DX reception in your area is important for a good television watching experience. If you feel your TV DX reception is lacking, and you can tell by the type of signal you receive in your area, contact your local television provider and find out how you can improve your signal.

Video on demand (VOD) allows for users to interface with a network and download streams of video to watch to their heart's content. It's an interactive television system. Generally, they are streams from the Internet but in the last year, technology has boomed in creating a seamless way to download programs to a digital device, such as a cable box. VOD can be downloaded to computers as well through cable providers and the use of cablecard technology. Cablecard technology inserts a card into your PC or television to allow for downloads from a cable provider without the use of a cable box.

However, VOD boxes allow you to download a maximum amount of programs into memory. During the time you have those programs on your box, they are yours to play. During play, you have complete control over your watching experience. You can pause, rewind, fast-forward or watch over and over again. Typically, if you download the program to your box, your controls will be faster than if you stream the program directly to watch. Streaming increases the network bandwidth of the host's server which decreases your ability to watch a program without interruption.

These streaming networks can be created in many ways to reduce lag time and allow for an uninterrupted program. Local Area Networks (LANs) as well as Wide Area Networks (WANs) can host videos, and the more high-speed connections hosting particular files will allow for greater bandwidth and a higher share speed. WANs, however, are generally smaller and confined to no more than seven to ten computers. If these computers are all high-speed, their power to produce a great downloading connection increases and allows for a higher quality stream. Both systems provide a higher response for downloaders, and the more users you have on a network, the more sharing that goes on and the more you're able to find to watch on your computer or television.

Commercially, VOD technology was born in the early 90s in Hong Kong by cable provider Telecon. Since video CDs were still cheaper to produce, VOD technology was sporadic and produced low-quality streams as well as downloads to users. At the time, only specific areas and generally the rich could afford to find what they were looking for on a network. Telecon lost millions of dollars investing in the technology at the time and eventually went bankrupt trying to recover.

In the United States, VOD services are widely available all over the country. EchoStar, Comcast and Cox Communications all provide VOD services to their consumers and regions. While most provide a strictly downloadable VOD technology, which stores information in a cable box, some are venturing out to provide streaming technology in the near future. Cable boxes, such as those provided by Comcast and DirecTV, allow users to store programs for an undetermined amount of time. Typically, television programming on premium channels can be stored conceivably forever whereas pay-per-view movies can only be stored for a limited amount of time.

While downloaded onto these cable boxes, a customer can view them as often as they want with that particular box. Even pay-per-view movies, limited in the time allowed on the box, can be viewed over and over again. Some cable providers rent out digital video recorder (DVR) boxes that not only allow you to download or stream programs but also allows consumers to record live television for viewing later, much like a VCR. DVRs are what some call the way of the future and have made an impact in most markets as a viable replacement to clunky VCRs and VHS tapes that degrade over time. DVR boxes provide everyone with the chance to keep up with their favorite shows, watch their favorite movies and not have to leave their home for the video store.

Video on demand technology is just one way cable providers are allowing customers to indulge in the evolution of television and film. Whether you're downloading shows, recording them to watch at a future date or just saving your favorite films to enjoy with the family, VOD technology is the way of the future and the way to enjoy movies and film no matter how you watch them during your day. VOD is the way of the future and along with DVR technology, the way to watch television and film in the busy world.

The aspect ratio of your television determines the type of picture being broadcast for your viewing pleasure. Widescreen and fullscreen pictures are the most common aspect ratios people are familiar with in today's golden age of television. DVDs are now produced in one or the other format, with most studios beginning to make the plunge towards only releasing widescreen films. However, fullscreen and widescreen are not the only types of aspect ratios out there. They're just the most familiar ones in the United States.

Aspect ratio refers to the displayed part of an image's width divided by its height. Most televisions have an aspect ratio of 4:3. With the introduction of high-definition television, this 4:3 ratio is being replaced with a 16:9 ratio. This higher ratio allows for more pixels to be broadcast and ensures for a clearer, crisper picture. The smaller the ratio, the less quality a picture is able to produce. While most people can't tell the difference, the easiest way to define widescreen and fullscreen is as follows.

Widescreen produces two letterboxes when shown on a screen, one at the top and one at the bottom, often black bars. These frame the picture and make it appear wider on the screen, whereas compared to a fullscreen production of the same image, you're able to see more to the left and right of the picture. Fullscreen stretches an image to fit your entire screen. There are no letterboxes or frames. This stretching cuts off much of what is to the left and right of the image and limiting your ability to take in the full environment of a particular television show or movie. Some films are released in both formats, others in just one. The trend seems to follow that widescreen is the way to go, but each person has their own preferences on how they want to view their favorites shows and movies.

Since the beginning of television production, the 4:3 ratio has been dominant. Most computer monitors also use this ratio to project images. The 16:9 ratio has only evolved in the last three or four years with the invention of high-definition television. It is also considered an international format that countries in Australia and Europe use on an everyday basis. Using high-definition cables as well as subscribing to channels broadcasting the higher ratio, you can experience high-definition from the comfort of your own living room. Japan, in recent years, switched from their standard 5:3 ratio to the 16:9 to comply with the international standard sweeping the east.

Anamorphic DVD transfers allow for a 16:9 picture to be stretched to the 4:3 ratio. Since many digital video cameras allow the user to change the aspect ratio on their own, the ability to be able to project the player on a given DVD player had to be addressed. This type of anamorphic technology does just that. During the process, the 16:9 picture is "stretched" during transmission to the 4:3 format which creates the widescreen picture you're used to viewing on both television and film today. Letterboxes are added the top and bottom portion of the picture in order to compensate for the lack of picture, framing the image. This is all done at the speed of light between the time you turn on your digital video camera and project it to your television or computer monitor.

Some older types of ratios include the pixel aspect ratio as well as the original aspect ratio. The original aspect ratio is generally reserved for a home theater experience. It refers to the way the film was originally shot by the production team, as created by a director and a team of producers. Pixel aspect ratio, often referred to as just plain old aspect ratio, is used in computer speak referring to the way pixels are digitized. Imaging systems use square pixels, much like a film image, and these too have to be reformatted depending on the size and ratio you need for your particular project.

Aspect ratios are bound to change as technology evolves into the future. High-definition television is just one stepping stone in increasing the ability to view a clear picture. As technology evolves, so does the ratio required to keep up with an audience's desire to seek a clearer picture on their television, movie and computer screens.