Abstract: High PRF and inverse receiver are often used in radar missile guidance. In such kind of system, the echo wave passes the narrrowband filter of the receiver, and become quasi-continuous wave. So a simple method can be used to achieve quadrature sampling through single channel sampling. In this paper, after several IF sampling methods have been discussed theoretically, a new simple method applied to missile guidance is advanced. This method simplifies the IF sampling circuits greatly. The error analysis as well as the theory and circuit of this method is also given.