DIGITAL TV TALK: Why Your TV Signals Are Affected By Rain

By Multichoice

Adverse weather conditions have been known to affect the quality of the satellite TV signal reception. This is popularly called “rain fade”. Usually, when this occurs, it is only for a short period of time.

In reality, heavy rains and cloudy conditions can affect television signals enough to result in noticeable degradation of image quality.

In very severe cases, reception can be effectively disrupted. Factors that determine how often this will happen include regional yearly rainfall figure, location in the satellite footprint and height of the satellite above horizon.

While it takes very heavy rain to affect signal reception of a properly aimed and wired satellite home system, still, it can and will occur where the conditions are present.

However, it is more likely to occur more areas with significant annual rainfall like tropical Africa or South America, especially in countries where rainfall is preceded by dense clouds or accompanied by strong storms. It is less likely in Europe and certain parts of the US. Still, it happens, only less frequently.

The major cause of signal degeneration is satellite wave absorption by the rain drops. There is also some signal scattering, due to deflection of satellite communication between one medium and another or interference between the wave forms produced.

But it is not only rainfall that causes signal degeneration. Very heavy snowing can also affect signal quality, but it is generally less likely to interfere.

Not all satellite signals are affected equally. In general, the longer radio wave, the less affected it is by the “rain fade”. Transmission via the longer C-band wavelength is significantly less susceptible to this kind of interference than  the one done via the shorter Ku-band (which is used by DStv) or Ka-band.

Also, the farther off central receiving area location, the more pronounced the effect of rain-fade effect is.

Often, susceptibility to rain fade  is symptomatic of a less than optimally aimed dish.

Reception quality also can be affected by water or snow/ice accumulating over the surface of a dish receptor. This may result in scatter and less efficient focusing of the satellite signal after its reflection from  the dish surface.

Most often, a yearly maintenance of the dish by a qualified maintenance hand will address this.

In temperate regions of the world, a special dish with built-in heater is used to prevent accumulation of ice.

Rain fade is neither exclusive to Nigeria nor Africa.