  The Australia Telescope 20GHz (AT20G) survey is a large area (2{\pi} sr),
sensitive (40mJy), high frequency (20GHz) survey of the southern sky. The
survey was conducted in two parts: an initial fast scanning survey, and a
series of more accurate follow-up observations. The follow-up survey catalog
has been presented by Murphy et al. 2010. In this paper we discuss the hardware
setup and scanning survey strategy as well as the production of the scanning
survey catalog.
