More basics on Direct Broadcast Satellite

Direct broadcast satellite (DBS) is a term used to refer to satellite television broadcasts intended for home reception, also referred to as direct-to-home signals. The expression direct-to-home or DTH was, initially, meant to distinguish the transmissions directly intended for home viewers from cable television distribution services that sometimes carried on the same satellite. The term predates DBS satellites and is often used in reference to services carried by lower power satellites which required larger dishes (1.7M diameter or greater) for reception. In Europe, the expression was common prior to the launch of ASTRA-1 in 1988 as there were two markets: the DTH market which required the larger dishes and the DBS (ASTRA) market which required smaller (0.9M dishes). As higher powered satellites like ASTRA came into operation, the acronym DBS gradually supplanted it.
The term DBS now covers both analog and digital television and radio reception, and is often extended to other services provided by modern digital television systems, including video-on-demand and interactive features. A "DBS service" usually refers to either a commercial service, or a group of free channels available from one orbital position targeting one country.

Direct from another blogger:
http://galaxyee.blogspot.com/2007/10/direct-broadcast-satellite.html