Fifteen seconds on ASA website:
ADS-B services are being implemented in stages during which time surveillance coverage will progressively increase. Currently, the system is supported by more than 60 duplicated ADS-B ground stations nationwide plus 14 ADS-B capable multilateration sites in Tasmania and 16 sites in the Sydney basin. These are now delivering continuous surveillance of aircraft operations high level airspace across western, central and northern Australia where radar coverage does not currently exsist. A further 14 ground stations are being considered to support the needs of airlines, regional and general aviation.