Abstract: As the general commercial instruments cannot satisfy the testing requirements for IQ orthogonality testing of modern navigation signal, a testing software for IQ orthogonality has been developed based on Matlab GUI. The software controls high-speed digital oscilloscope via the network interface and samples the PPS (Pulse Per second)and navigation signals of navigation signals source respectively in dual-channel. The navigation signal data is extracted according to the starting point of the navigation signal determined by the PPS. After digital waveform-matching of navigation signal has been done with the local pseudo-random code modulation wave, the carrier initial phase of I and Q branch can be precisely estimated, then the test result of IQ orthogonality is obtained. The software has characteristics of friendly interface, easy operation, intuitive display. The simulation results show that random error of the test result is less than 0.5 degrees in the case of typical carrier to noise ratio.

Key words: Navigation, Signal, Carrier to noise ratio, Orthogonality, Test software