Meaning of BASEBAND in English
Video and audio signals are considered to be "prime", or baseband. Video and audio can be broken down into more basic elements, but those elements no longer constitute the desired signal as a single element. Baseband video and audio signals are often AM or FM modulated onto a carrier frequency, so that more than one set of "prime" signals can be transmitted or recorded at the same time.
Film and video English vocabulary. Английский словарь фильмов и видео. 2012