Improved continuous wave frequency modulated sonars with aural displays

This paper discusses methods for reducing the effects of the reset hiatus and wavelength related variations in received signal strength on the aural displays produced by simple continuous wave frequency modulated sonars. Two techniques that have been developed for reducing the effects of signal phase and amplitude discontinuities are described. As a practical example of the improved performance afforded by one of these techniques, a novel short range sonar for examining cardiovascular structures is discussed in detail.