Vol. 6 - No. 6


In our April issue we discussed satellites and understanding some of the terminology used in adjusting the satellite dish to receive a signal.  This month we will continue that discussion and learn how satellite signals are different than other radio and TV signals.

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As a child I received a gift of a crystal set radio much like the photo above..  This turned out to be one of my favorite gifts.  It used no power, just a lump of crystal, a "cat whisker" probe, a set of earphones and a long wire antenna.  With patience, you could listen to over the air broadcasts.  The great thing about it was night-time reception.   Because radio waves are transmitted by powerful transmitters, the signals can "bounce or skip" many times before losing strength.  During the daytime the Ionosphere layer of the atmosphere is lower and closer to the Earth's surface.   The radio waves hit this layer and bounce sooner and in shorter distances than at night.  At night the Ionosphere layer disappears or merges into the upper layers, creating a higher ceiling for the radio waves to bounce off.  Because of the higher bounce, the distance is much greater at night.  It is therefore possible to hear radio stations from Europe on the East coast of the United States, or even further depending on the wattage used to transmit.  As a kid I thought it was great to be able to listen to French and German radio stations.

So, how does this relate to satellite TV signals?  It doesn't - satellite TV signals are about as opposite of these radio signals as you can get.

Satellite TV signals start out on Earth at the provider's (DirecTV, DishNet, etc.) transmitting station where the programming is beamed up to the various satellites.  The signal consists of packets of data rather than modulated radio and TV waves.  The signal is also very weak in comparison to other transmitted signals.  That is why a dish is needed to gather and focus the signal on the LNB head.

Because the satellite signal is very weak - 10 watts of power vs thousands of watts for over the air - the signals do not bounce very far when they hit an object.  So, if anything is between the satellite's signal and the face of your dish, you won't get a signal.  You must have a clear, unobstructed view of the satellite to get satellite TV.   Now satellite radio is a slightly different story, but we won't get into that here.