On the basis of introducing the limitations of the double-star positioning system

the precision rubidium clock was put forward to be the internal clock of the RDSS receiver.If the receiver could measure the pseudo-ranges from the user to the satellites

with the help of barometer

the RDSS could be integrated with the strap-down inertial navigation system based on pseudo-range.The simulation result shows that the output navigation parameters of the integrated sys-tem have the characteristic of low error

which offers one new way to develop our country’s RDSS.