Extraction of reference signal is an indispensable step in the signal processing of polarization diversity passive radar (PDPR) based on a digital television signal. A conventional reference signal extraction method requires an additional reference antenna, which has a certain demand for space. Single dual-polarization antenna passive radar (SDPPR) systems do not require a reference antenna, and the radar station layout is flexible, which is suitable for a large-scale radar network. It is a main research direction of PDPR in future. However, its reference signal extraction needs to rely on the signal reconstruction method. When the signal to interference and noise ratio of the direct-path signal is relatively low, the signal reconstruction method will fail. In this paper, we propose a reference signal extraction method based on sub-carrier processing method, blind adaptive oblique projection technology, and extensive cancelation algorithm to solve the above problem. Experimental results show that the method proposed in this paper is a reasonable alternative after the failure of reference signal reconstruction, and it is an effective supplement to the reference signal extraction technology.