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.
