Abstract: A marine sonar device comprises a display, a sonar element, and a processing element. The display displays sonar images. The sonar element generates a sonar beam during a ping and presents transducer signals. The processing element is configured to instruct the sonar element to generate the sonar beam at a first frequency during a first ping, receive a first transducer signal resulting from received reflections of the sonar beam at the first frequency, filter the first transducer signal to exclude frequencies other than the first frequency, instruct the sonar element to generate the sonar beam at a second frequency during a second ping, the second frequency being different from the first frequency, receive a second transducer signal resulting from received reflections of the sonar beam at the second frequency, and filter the second transducer signal to exclude frequencies other than the second frequency.