Why are some echo sounders dual frequency?
When acoustic energy travels through the water, the frequency of that energy determines how deep it will travel and also the level of definition you can expect to see after it has bounced off of an object below. The lower frequencies, (50 kHz) provide better ground discrimination and also detect fish better in deeper water. The higher frequencies, (200 kHz) will detect fish such as mackerel and squid with no swim bladders easier and usually provide better discrimination between schools of fish and individual large fish. Having a dual frequency echo sounder gives you the advantage of having a deep penetrating lower frequency and a high definition higher frequency. Back to top.
