Satellite broadcasting in Japan digitized sound data for the first time in the history of broadcasting. This was made possible by the employment of Pulse Code Modulation (PCM) technology, the principle of which was discovered in 1937. This is the same technology that is currently used on CDs. Satellite broadcasting made new sound modes available, such as a B-mode stereo service providing a higher sound quality than that of CDs, a surround stereo service providing a higher sense of reality, and a bilingual stereo service. The digitization of satellite broadcasting sound will be part of ISDB (Integrated Services Digital Broadcasting), which will broadcast various types of information in a digital format.