A digital television adapter (DTA), commonly known as a converter box or decoder box, is a television tuner that receives a digital television (DTV) transmission, and converts the digital signal into an analog signal that can be received and displayed on an analog television set. Some also have an HDMI output since some TVs with HDMI do not have a digital tuner. The input digital signal may be over-the-air terrestrial television signals received by a television antenna, or signals from a digital cable system. It normally does not refer to satellite TV, which has always required a set-top box either to operate the big satellite dish, or to be the integrated receiver/decoder (IRD) in the case of direct-broadcast satellites (DBS).
In North America and South Korea, these ATSC tuner boxes convert from ATSC to NTSC, while in most of Europe and other places such as Australia and most Asian countries, they convert from Digital Video Broadcasting (DVB) to PAL, and in Japan, the Philippines and almost all countries in Latin America, they convert from ISDB-T to either NTSC or PAL. Because the DTV transition did nothing to reduce the number of broadcast television system standards (and in fact further complicated them), and due to varying frequency allocations and bandplans, there are many other combinations specific to other countries.