In the field of seakeeping, it is very important to know the characteristics of waves generated by a ship in the far field. An experimental method to analyse the wave pattern generated by a ship in waves, Unsteady Wave Pattern Analysis, has been proposed by Ohkusu. In this method, the following two problems should be examined. (1) Correction for the truncation of measured wave records to avoid the effect of reflection wave from tank wall. (Truncation correction) (2) Effect of the distance of wave probe from the model center line. (Y effect) In this paper these two problems in the unsteady wave pattern analysis are studied by the experiments with blunt bow ship model and the informations on wave pattern due to pulsating source with forward velocity.