A system for finding up in a projectile flight relative to earth. The system having a transmitter which transmits polarized reference signals to a guidance sub-system on the projectile. The guidance sub-system includes a magnetometer and polarized and non-polarized receivers. Measurements from the magnetometer are used to determine a general up direction. The polarized and non-polarized receivers are arranged such that, during rotation of the projectile, reference signals received by the polarized receiver modulate whereas reference signals received by the non-polarized receivers are unaffected. A ratio of the strengths of the signals received by the polarized and non-polarized receivers determines alignment of a vertical axis. From the general up direction and alignment of the vertical axis, a precise up direction of the projectile in flight relative to the earth can be determined.