Broadcast of HDTV programming, which has six times the information of standard TV programs necessitated advances in the technologies of video compression and transmission. In 1990, General Instrument of the United States constructed a digital TV system called DigiCipher capable of transmitting HDTV on a terrestrial broadcasting channel. Issues regarding compression technology were later examined by the MPEG working group of the International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), and an MPEG-2 international standard using a technology based on Discrete Cosine Transformation (DCT) and motion compensation (MC) was complied in 1994. In Europe, a digital satellite broadcasting system called DVB-S using MPEG-2 and QPSK modulation scheme was implemented for multi-channel broadcasting, starting in 1995. Japan commenced digital CS broadcasting based on the DVB-S system as well in 1996.
The digital BS broadcasting transmission system adopts a trellis 8PSK as its modulation scheme. With it, all broadcasters, NHK and commercial key broadcasters in Tokyo, provide services featuring HDTV on a limited number of channels. This makes possible broadcasting operations over a wider band, and in more flexible manner, than what is available through the European system.