Complex sentence: In the 1970s and 1980s, the popularity of traditional travelogues declined but the advent of cable television channels, such as the Discovery Channel and the availability of small, high quality, digital video equipment has renewed the popularity of travel films.
Split into simpler sentences: In the 1970s and 1980s, the popularity of traditional travelogues declined. But the advent of cable television channels, such as the Discovery Channel and the availability of small, high quality, digital video equipment has renewed the popularity of travel films.