Satellite Television

When a television is turned on, the broadcast station converts data into microwave signals, then sends them up to a satellite. These signals are retransmitted continually into a dish. The dish sends the microwave signals into a receiver with a broadband antenna to collect electromagnetic energy.

Depending on the receiver, the microwave signals are converted to analog, Digital or High-Definition frequencies, and signals. These ensure that the TVRO (a television receive-only earth station designed to only receive and not to transmit satellite communications) antenna has a clear view of each satellite. Any obstruction can absorb or reflect microwaves and subsequently lower the detected SNR (Signal-to-Noise Ratio) and hinder the TV reception.

TI (Terrestrial Interference) is the direct interference from natural and unnatural antenna frequency. Interference, mainly from telephone companies’ microwave transmissions, causes signal loss and makes pictures unwatchable. Even water in deciduous trees is a particularly strong absorber of microwaves.

LNA (low-noise-amplifier) is the basic building block of every satellite system dish. If the LNA is poor, then even a 15 ft dish on Galaxy 1 won’t give a good picture. It is considered as the heart of the system. If the signal-to-noise ratio is allowed to drop too low or is “in the mud”, no level of amplification will improve the image. Having too much signal power is never a problem.

A feedhorn is a device that collects microwave signals reflected from the surface of an antenna. An LNA on the other hand, is a short piece of metal with varying shapes and sizes designed to effectively transfer the microwaves from the focal point (exact center) of a waveguide into the feedhorn.

To work adequately, the LNA must be correctly situated on the dish and attached properly to the feedhorn. Signals are routed through the feedhorn, which is the antenna of a satellite receiver, and into the LNA.

If the feedhorn is off the center, the LNA adds excessive noise or doesn’t add enough gain (input power often expressed as decibels), or the dish doesn’t add enough gain, no matter what happens after the LNA contact, the picture will not be clear once the signal from the receiver drops below 40%.

Once entered into LNA, the signals are amplified 100,000 times so that there would be enough signal to drive the RG cable, which connects the direct current into the receiver. These signals are at a level of about 120dBm. dBm is a ratio of power level used to indicate gains or losses of signals. The receiver converts these signals into the television either as digital or High-Definition frequencies to bring the viewers pictures and sound.