In this paper, we compared and analyzed the performance of the GPS L1/L2 signal with GPS L1 using the navigation system. Generally the GPS receiver calculates the position of the satellite by using the ephemeris data recevied from GSP Satellites, and also calculates the position of its own using the pseudorange. This paper provides an overview of the device which can receive an GPS L1/L2, and compares the GPS L1 with the GPS L2 signal power using the simulator. It was confirmed that the GPS L1/L2 receiver and the GPS L1 receiver met the requirements of standards and it is similar to the navigation performance of the GPS L1 Receiver with the GPS L1/L2 receiver. It was also confirmed that the GPS L2 band can not correct ionospheric error in the navigation system of the combat vehicle.