A global positioning system includes a fixed base unit of known position and at least one mobile unit, the base unit and the mobile unit each including a GPS receiver. This system further includes means for comparing the simultaneous GPS identified positions of the mobile unit and the base unit to establish the relative position of the mobile unit to the base unit. The mobile unit may be provided in a vehicle for allowing the instantaneous position of the vehicle to be identified relative to the base unit. Alternatively the mobile unit may include a bar code scanner for reading a bar code on an item and recording instantaneously the GPS identified position allowing a map of the position of various items relative to a base unit to be compiled.