2. IMPORTANT OVERVIEW
2-1. Sending Signals
Analog Cable service
Digital broadcasting is a new way of sending programs over the airwaves with superior qual-
ity video and audio. The DIRECTV® HD Receiver enables you to take full advantage of digital
broadcasting. To fully enjoy it, it is helpful understand the ways the program signals are sent.
There are two types of TV signal formats; analog (often called NTSC format; National Television
System Committee) and digital (ATSC format; Advanced Television System Committee). Digital
formats are classified into three categories: High-Definition (HD), Enhanced Definition (ED), and
Standard Definition (SO) according to the resolution or digital picture quality.
There are also three ways that program signals can be received; over-the-air (NTSC, ATSC),
cable and satellite.