This article is from the TeleVision Receive Only Satellite-TV FAQ, by TVRO Hobbyists firstname.lastname@example.org with numerous contributions by others.
Satellite transmissions start with the uplink signal, which are
transmitted by very large fixed satellite dishes up to the satellite
in orbit above the earth. The satellite then retransmits the signal on
a lower frequency down to a general geographic area of the earth with
what is called the downlink signal. On the ground, home satellite
receiving equipment converts the downlink frequencies to the even
lower 950-1450 MHz standard frequency block. The signal then travels
to the satellite receiver for modulation to TV channel 3 and is then
sent to the television itself.