The invention includes computer system to emulate a magstripe card reader connected to a fuel dispenser terminal based on radio frequency signals, the system having a first radio frequency transmitting antenna, a separate first radio frequency receiving antenna and a controller for electronically controlling the system which is connected to both the transmitting and receiving antenna. The controller is adapted to develop and emulate magstripe card reader signals based on signals received from the receiving antenna. A multiplexer is utilized for selectively communicating magstripe card reader signals from the controller to the fuel dispenser terminal system. A method is described of combining a radio frequency tag identification system having a multiplexer with a fuel dispenser system by disconnecting a magstripe card reader from a fuel dispenser system card reader input, connecting the radio frequency tag identification system multiplexer to the fuel dispenser system card reader input; and then connecting the previously disconnected magstripe card reader to the multiplexer.