Frequency analysis has been performed for the oblique shockwave boundary layer interaction (OSWBLI). Rainbow Schlieren Deflectometry (RSD) has been used to capture the flow data at 5000 frames per second. The experimental setup produces a free stream flow of Mach 3.1. This flow upon encountering a 12° isosceles triangular prism attached to the roof of the test section generates the required oblique shock in the test section. The RSD pictures were used for data analysis to determine the transverse ray deflections at each pixel of the pictures. Fast Fourier Transform (FFT) has been applied to this data to capture the frequency content of the flow field. Analysis is also performed on data at 30,000 frames per second data to compare the results with previous work on SWBLI. The analysis concentrates on the regions of interest which is in the vicinity of the separation bubble including the incident, transmitted and reflected shock regions. © 2017 by the American Institute of Aeronautics and Astronautics, Inc.