Spectral processor and range display unit

摘要

An apparatus for converting the difference frequency between the transmit pulse of a sonar and the return or receive signal from a target to a video representation complementing the audio output of the sonar representing the difference frequency. The audio and complementing video signal indicate the presence of the target and its range. The invention converts the audio signal to a frequency spectrogram by means of digital signal processing including a FFT algorithm. The amplitudes of the frequency components of the audio signal are plotted on the video display of the invention. They are color-coded to indicate the amplitude of the audio signal. The frequency of the audio signal is related to the range of an object detected by the sonar. The invention is mobile and easily managed by a diver.