You Asked:
Is it possible for a signal transmitted through satellite TV not to be digital? — Ed, Nairobi, Kenya

Marshall Answered:
If you think back a couple of decades, there was an era where people in the U.S. put big 6-foot or 8-foot satellite dish antennas in their yards. The reason they did this is because different cable channels and television stations were transmitting their programs to all their affiliates across the country using satellites. So, for example, the HBO main office would send its programming up to a satellite. The satellite would rebroadcast it down to earth. In each city, the local cable company would pick up the signal with a satellite dish antenna and put it on the cable system.

In the early days these signals were analog and they had no encryption. Therefore, a person with a big antenna in the yard could aim the antenna at the right satellite and receive the analog signal. With a little conditioning the signal could drive an analog TV.

Today, satellite TV signals are all digital, they are encrypted and they come from satellites with much higher power. Therefore the antennas are much smaller and you need a box that can decode the signals. For more info see: How Satellite TV Works