Figure 23 . Schools of herring used to compare CW data and CW components extracted from FM data. The upper panel shows the echogram, and the schools encircled in red that are used to make the frequency response. A section of the frequency response at 120 kHz is enlarged. First point is EK80 CW data, second point shows the complete EK80 band of the 120-kHz channel used in the pulse-compression. The following points show decreasing bands used in the pulse-compression until the final that contains only 3 kHz that is expected to be the bandwidth used by the CW signal.