Active Echo Fishing Lure

More and more fishing hobbyists use boat sonar to detect fishes and underwater structure. These sonars operate on the same principle as medical ultrasonography systems. They fire ultrasound pulses and receive the echo signal. Based on the signal time-of-flight (TOF) and phase, the image is reconstructed. These sonars work at a frequency between 100k to 400kHz (compared to MHz for medical ultrasound), and capable to provide underwater ultrasound images with a refresh rate of few Hertz. Large fish, fish schools, and other large underwater objects can show up in the ultrasound image. However, fishing lures cannot be seen on the sonar images due to their small size. A typical fishing lure is made of plastic, metal and/or rubber, with a weight of few grams to tens of grams, and a size of few centimeters. Furthermore, passive reflectors cannot be effectively used in this case because the reflectors would change the appearance and motion of the lure; these effects are highly undesirable since they make the lure “un-natural” and will repel, rather than attract, fish. Since it is not visible on the sonar display, fishing hobbyist cannot use the ultrasound image to figure out the relative distance between the lure and fish. Based on our preliminary survey, fishing hobbyists have a great interest of having a sonar visible lure. With the lure visible, it may be possible to guide the lure to the fish rather than waiting for the fish to come to the lure, much like guiding a biopsy needle to a tumor. This may be a game changer for the fisherman. Moreover, such a system may also be useful for commercial fishermen and for placement of other small, or otherwise invisible, objects underwater.

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