Knudsen Engineering Limited (KEL), is located in Canada and has been designing and building echosounders for most of its twenty one year existence. Starting in the late 1980's with the 320A, designed for helicopter surveys in the high Arctic, and continuing with the 320M, 320B and their derivatives, Knudsen echosounders are now used in more than 60 countries around the world. Known for their pioneering use of digital signal processing (DSP) technology, Knudsen sounders are used in a wide range of applications, from shallow-water hydrographic survey to full-ocean depth scientific research. Knudsen Engineering, Perth Ontario. Knudsen Engineering, Perth Ontario Knudsen Engineering Limited is located in historic Perth, Ontario - close to Ottawa, Canada's capital.