generate questions: BeiDou-1 is an experimental regional navigation system, which consists of four satellites (three working satellites and one backup satellite). The satellites themselves were based on the Chinese DFH-3 geostationary communications satellite and had a launch weight of 1,000 kilograms (2,200 pounds) each.
What is the BeiDou-1? {sep_token} The BeiDou-1 is made up of how may satellites? {sep_token} How many satellites in the BeiDou-1 system is used for back up? {sep_token} What were the BeiDou-1 system satellites based on? {sep_token} How much did each satellite for the BeiDou-1 system weigh? {sep_token}