An underwater detection apparatus for detecting a target by transmitting and receiving an ultrasound signal is provided. The controller generates this series of test waveforms by direct synthesis to cause each waveform to contain a respective different predetermined amount of Rj, Sj and ISI jitter components. A temporal or spatial filter is used to selectively block visible light from one or more portions of the detector while passing the structured illumination to the one or more portions of the detector.