Complex sentence: HBO Brasil was launched in 1991 by TVA, Time Warner and Sony as an analogue pay channel, but using over-the-air UHF frequencies and broadcasting for nine hours each day.
Split into simpler sentences: HBO Brasil was launched in 1991 as a partnership between Televisão Abril, Time Warner and Sony. It was developed as an analogue pay channel, but used UHF broadcast frequencies and ran its programming for nine hours each day.