The interferometric fiber sensor is applicable in many fields for its high sensitivity, but the polarization induced signal fading is a serious problem. We proposed an orthogonal-polarization switching method and a signal synthesis algorithm based on the phase generated carrier (PGC) scheme to solve the problem for the pulse interrogation. The principle of the method was demonstrated and an algorithm for signal synthesis was derived based on the PGC scheme. The experimental results show that the equivalent visibility is steady between 0.93 and 0.94, and the background noise of the synthesized signal is lower than that of all the four polarization channels. The method can eliminate the polarization induced low frequency phase drift as well, making the synthesis results not influenced by perturbation of polarization states. The long time measurement results demonstrate that the background noise can reach -96 dB/Hz at 1 kHz when the frequency of the PGC demodulation was 8 kHz. This result is equivalent to that of the system with the Faraday rotator mirrors. This method is applicable for solving the signal fading problem in the time division multiplexing sensor array especially for the inline interferometric fiber sensor array based on fiber Bragg gratings and the distributed sensor array.