UNDERWATER DETECTION DEVICE, UNDERWATER DETECTION METHOD AND UNDERWATER DETECTION PROGRAM

PROBLEM TO BE SOLVED: To suppress a range side lobe due to a target having the high signal level of an echo such as the sea bottom.SOLUTION: A range side lobe suppression section 70 of an underwater detection device comprises: a suppression range setting section 71; a suppression exclusion range setting section 72; a suppression value setting section 73; and a suppression arithmetic section 74. The suppression range setting section 71 sets a suppression range on the basis of the signal level of each position of pulse compression data. The suppression exclusion range setting section 72 compares a threshold for suppression exclusion range setting approximated to the envelope of the peak of a range side lobe with the signal level of each position to set a suppression exclusion range. The suppression value setting section 73 calculates a suppression value SS offset by the rate of the signal level of the suppression range to a signal level beyond the suppression range, and approximated to the envelope of the peak of the range side lobe. The suppression arithmetic section 74 suppresses the signal level of pulse compression data with the suppression value at each position in the suppression range to suppress the range side lobe corresponding to the pulse compression data.